These roofing terms are cited from the "WSRCA
Glossary of Roofing Terms" in the WSRCA Day Planner.
A | B | C | D | E | F | G | H | I | J | K
| L | M | N | O | P | Q | R | S | T | U | V | W | X
| Y | Z
ATop of Page
Abrasion resistance: the ability to resist
being worn away by contact with another moving, abrasive surface, such as
foot traffic, mechanical equipment, wind-blown particles,
Absorption: the ability of a material to accept
within its body, quantities of gases or liquid, such as
Accelerated weathering: the exposure of a
specimen to a specified test environment for a specified time with the
intent of producing in a shorter time period, effects similar to actual
Acid etch: in waterproofing, the use of a
strong acid to remove the surface of concrete to expose the
Acrylic coating: a liquid coating system
based on an acrylic resin. Generally, a latex-based coating system that
cures by air drying.
Acrylic resin: polymers of
acrylic or methacrylic monomers. Often used as a latex base for coating
Active metal (anodic): a metal or material
that readily gives up electrons to a cathodic (noble) material. (See
anodic). An active metal will corrode in the presence of moisture when in
contact with a cathodic metal.
Adhesion: steady or
Adhesive bond break: a material to
facilitate independent movement between two units that would otherwise
Aggregate: (1) crushed stone, crushed
slag or water-worn gravel used for surfacing a built-up roof system; (2)
any granular material.
Aged R-value: thermal
resistance value established by utilizing artificial conditioning
procedures for a prescribed time period.
the unintended movement of air from a location where it is intended to be
contained to another location.
cracking of the surfacing bitumen on a bituminous roof or coating on a SPF
roof, producing a pattern of cracks similar to an alligator's hide; the
cracks may not extend completely through the surfacing bitumen or
Aluminized steel: sheet steel with a thin
aluminum coating bonded to the surface to enhance weathering
Aluminum: a nonrusting, malleable
metal sometimes used for metal roofing and
Anodic: a metal or material that readily
gives up electrons to a cathodic material in the presence of an
electrolyte (see Galvanic series).
National Standards Institute.
Anticapillary hem: a hem
used in a metal panel seam to reduce the potential for water
APA: American Plywood
APC: American Plastics
APP: see Atactic
Application rate: the average quantity
(mass, volume or thickness) of material applied per unit
Apron flashing: a term used for a flashing
located at the juncture of the top of a sloped roof and a vertical wall,
chimney or steeper-sloped roof.
Plastics Council/Spray Polyurethane Foam
Architectural panel: a metal roof panel,
typically a double standing seam or batten seam; usually requires solid
decking underneath and relies on slope to shed
Architectural shingle: an asphalt shingle that
provides a dimensional appearance.
raised, flashed assembly, typically a single- or double-wood member
attached to a wood base plate, that is anchored to the roof deck. It is
used to accommodate thermal stresses in a roof system where an expansion
joint is not required, or to separate large roof areas or separate roof
systems comprised of different/incompatible materials, and may be used to
facilitate installation of tapered insulation.
Asphalt Roofing Manufacturers Association.
practices: design or application techniques peculiar to a
specific geographical region.
Asbestos: a group of
natural, fibrous, impure silicate materials.
American Society of Heating, Refrigerating and Air-Conditioning
Asphalt: a dark brown or black substance
found in a natural state or, more commonly, left as a residue after
evaporating or otherwise processing crude oil or petroleum. Asphalt may be
further refined to conform to various roofing grade
·Dead-level asphalt: a roofing asphalt
conforming to the requirements of ASTM Specification D312, Type
·Flat asphalt: a roofing asphalt conforming to the
requirements of ASTM Specification D 312, Type II.
asphalt: a roofing asphalt conforming to the requirements of ASTM
Specification D 312, Type III.
·Special steep asphalt:
a roofing asphalt conforming to the requirements of ASTM Specification D
312, Type IV.
Asphalt, Air blown: asphalt produced by
blowing air through molten asphalt to raise its softening point and modify
Asphalt emulsion: a mixture of
asphalt particles and emulsifying agent, such as bentonite clay and
Asphalt felt: an asphalt-saturated and/or
asphalt-coated felt (see Felt).
Asphalt primer: see
Asphalt roof cement: a trowelable mixture of
solvent-based bitumen, mineral stabilizers, other fibers and/or fillers.
Classified by ASTM Standard D 2822-1 Asphalt Roof Cement, and D 4586-2
Asphalt Roof Cement, Asbestos-Free, Types I and II. Type I is sometimes
referred to as “plastic cement,” and is made from asphalt characterized as
self-sealing, adhesive and ductile, and conforming to ASTM Specification D
312, Type I; Specification D 449,
Types I or II; or Specification D 946
(see Plastic cement and Flashing cement.)
Type II is generally referred
to as “vertical-grade flashing cement,” and is made from asphalt
characterized by a high softening point and relatively low ductility, and
conforming to the requirement of ASTM Specification D 312,
Types II or
III; or Specification D 449, Type III. (see Plastic cement and Flashing
Asphalt shingle: a shingle manufactured by
coating a reinforcing material (felt or fibrous glass mat) with asphalt
and having mineral granules on the side exposed to the weather. (see
Asphaltene: a high molecular weight
hydrocarbon fraction precipitated from asphalt by a designated solvent
(paraffinic naphtha) at a specified temperature and solvent-asphalt
ASTM: American Society for Testing and
Atactic polypropylene: a group of high
molecular weight polymers formed by the polymerization of
Attic: the cavity or open space above the
ceiling and immediately under the roof deck of a steep-sloped
Back-nailing (also referred to as
“Blind-nailing”): the practice of blind nailing the back portion
of a roofing ply, steep roofing unit, or other components in a manner so
that the fasteners are covered by the next sequential ply, or course, and
are not exposed to the weather in the finished roof
Ballast: a material, such as aggregate or
precast concrete pavers, which employs its mass and the force of gravity
to hold (or assist in holding) single-ply roof membranes in
Bar joist: (see Steel joist).
vault: a building profile featuring a rounded profile to the roof
on the short axis, but with no angle change on a cut along the long
Barrier board: noncombustible board stock
material of low thermal conductivity placed between two elements of a roof
Base flashing (membrane base flashing):
plies or strips of roof membrane material used to close-off and/or seal a
roof at the horizontal-to-vertical intersections, such as at a
roof-to-wall juncture. Membrane base flashing covers the edge of the field
membrane. (see Flashing.)
Base ply: the bottom or
first ply in a built-up roof membrane when additional plies are to be
Base sheet: an impregnated,
saturated, or coated felt placed as the first ply in some low-slope roof
Batten: (1) cap or cover; (2) in a metal
roof, a metal closure set over, or covering the joint between, adjacent
metal panels; (3) in a wood roof, a strip of wood usually set in or over
the structural deck, used to elevate and/or attach a primary roof covering
such as tile; (4) in a single ply membrane roof system, a narrow plastic,
wood or metal bar that is used to fasten or hold the roof membrane and/or
base flashing in place.
Batten seam: a metal panel
profile attached to and formed around a beveled wood or metal
Bentonite: a porous clay formed by the
decomposition of volcanic ash that swells 5 to 6 times its original volume
in the presence of water.
Bermuda seam: a metal panel
profile featuring a step-down profile that runs perpendicular to the slope
of the roof.
Bird bath: random, inconsequential
amounts of residual water on a roof membrane.
(1) a class of amorphous, black or dark colored, (solid,
semi-solid or viscous) cementitious substances, natural or manufactured,
composed principally of high molecular weight hydrocarbons, soluble in
carbon disulfide, and found in asphalts, tars, pitches and asphaltenes;
(2) a generic term used to denote any material composed principally of
bitumen, typically asphalt or coal tar.
see Envelope or Bleed-sheet.
Bituminous emulsion: a
suspension of minute particles of bituminous material in
Blackberry (also referred to as “Blueberry” or
“Tar-boil”): a small bubble or blister in the flood coat of an
aggregate-surfaced built-up roof membrane.
insulation: glass fiber or other compressible fibrous insulation,
generally available in roll form.
Bleed-sheet: a sheet
material used to prevent the migration of bitumen.
strip: (see Rake-starter).
use of nails that are not exposed to the weather in the finished roofing
Blister: an enclosed pocket of air, which may
be mixed with water or solvent vapor, trapped between impermeable layers
of felt or membrane, or between the membrane and
Blocking: sections of wood (which may be
preservative treated) built into a roof assembly, usually attached above
the deck and below the membrane or flashing, used to stiffen the deck
around an opening, act as a stop for insulation, support a curb, or serve
as a nailer for attachment of the membrane and/or
Blowing agent: an expanding agent used to
produce a gas by chemical or thermal action, or both, in manufacture of
hollow or cellular materials.
BOCA: Building Officials
and Code Administrators, International, Inc.
adhesive and/or cohesive forces holding two components in positive
Boot: (1) a covering made of flexible
material, which may be preformed to a particular shape, used to exclude
dust, dirt, moisture, etc., from around a penetration; (2) a flexible
material used to form a closure, sometimes installed at inside and outside
Brake: hand- or power-activated machinery
used to bend metal.
Bridging: (1) when membrane or
base flashing is unsupported at a juncture; (2) bridging in steep-slope
roofing occurs when reroofing over standard-sized asphalt shingles with
metric-sized asphalt shingles.
British thermal unit
(BTU): the heat energy required to raise the temperature of 1
pound of water degree Fahrenheit (joule). For the metric equivalent, see
Broadcast: uniformly cast or distribute
granular or aggregate surfacing material.
improve the embedding of a ply or membrane by using a broom or squeegee to
smooth it out and ensure contact with the adhesive under the ply or
Buckle: an upward, elongated displacement of
a roof membrane frequently occurring over insulation or deck joints. A
buckle may be an indication of movement within the roof
Building code: The minimum construction
requirements established generally by national organizations of experts
and adopted completely or in altered form by local governing
Built-up roof (BUR): a continuous,
semi-flexible roof membrane, consisting of multiple plies of saturated
felts, coated felts, fabrics or mats assembled in place with alternate
layers of bitumen, and surfaced with mineral aggregate, bituminous
materials, a liquid-applied coating or a granule-surfaced cap
Bundle: an individual package of shakes or
Bun stock: large solid box-like structure
formed during the production of polystyrene insulation; individual board
stock pieces are then cut from the bun.
Butt joint: a
joint formed by adjacent, separate sections of material, such as where two
neighboring pieces of insulation abut.
Button punch: a
process of indenting two or more thicknesses of metal that are pressed
against each other to prevent slippage between the
Butyl: rubber-like material produced by
Butyl coating: an
elastomeric coating system derived from polymerized isobutylene. Butyl
coatings are characterized by low water vapor
Butyl rubber: a synthetic elastomer
based on isobutylene and a minor amount of isoprene. It can be vulcanized
and features low permeability to gases and water vapor.
tape: a sealant tape sometimes used between metal roof panel
seams and/or end laps; also used to seal other types of sheet metal
joints, and in various sealant applications.
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Calender: (1) to press between rollers or
plates in order to smooth and glaze or to thin into sheets; (2) a machine
Camber: a slight convexity, arching
or curvature (as of a beam, roof deck or
Canopy: any overhanging or projecting roof
structure, typically over entrances or doors.
SPF-based roofing, a beveling of foam at horizontal/vertical joints to
increase strength and promote water run off.
strip: a beveled strip used under flashings to modify the angle
at the point where the roofing or waterproofing membrane meets any
Cap flashing: (1) usually composed
of metal, used to cover or shield the upper edges of the membrane base
flashing wall flashing; (2) a flashing used to cover the top of various
buildings components, such as parapets or
columns. (see Flashing and
Cap sheet: a sheet, often granule-surfaced,
used as the top ply of some built-up or modified bitumen roof membranes
Capacitance meter: a device used to
locate moisture or wet materials within a roof system by measuring the
ratio of the change to the potential difference between two conducting
elements separated by a non-conductor.
action: (1) the action by which the surface of a liquid where it
is in contact with a solid is elevated or depressed depending on the
relative attraction of the molecules of the liquid for each other and for
those of the solid; (2) the siphoning of liquid into a joint or void
between two adjacent surfaces.
Catalyst: an ingredient
that initiates a chemical reaction or increases the rate of a chemical
reaction when combined with another
Cathodic: A metal or material that readily
attracts electrons from an anodic material in the presence of an
electrolyte (see Galvanic Series).
composition of vehicle and pigment used at ambient temperatures for
filling/sealing joints or junctures, that remains elastic for an extended
period of time after application.
Caulking: (1) the
physical process of sealing a joint or juncture; (2) sealing and making
weather-tight the joints, seams or voids between adjacent surfaces by
filling with a sealant.
Cavitation: the formation of a
partial vacuum or cavity in a liquid.
Cavity wall: an
exterior wall usually of masonry, consisting of an outer and inner withe
separated by a continuous air space, but connected together by wire or
C-channel: a structural framing
Cellular glass insulation: A rigid closed-cell
insulation board made from crushed glass and hydrogen sulfide
Cementitious waterproofing: heavy cement-based
compounds and various additives that are mixed and packaged for use in a
dry form; the packaged mixture is then mixed with water and liquid bonding
agents to a workable concrete-like
Centipoise: a unit of measure of absolute
viscosity. (The viscosity of water is one centipoise. The lower the
number, the less viscous the material.)
unit of viscosity; the ratio of a liquid’s absolute viscosity to the
density of that liquid.
CERL: Construction Engineering
Chalk: a powdery residue on the
surface of a material.
Chalk line: a line made on the
roof or other flat surface by snapping a taut string or cord dusted with
Chalking: the formation of a powdery
surface condition from the disintegration of a binder or
Channel flashing: in steep-slope roof
construction, a type of flashing used at roof-to-wall junctures and other
rooftop-vertical plane intersections where an internal gutter is needed to
handle runoff. Commonly used with profile tile.
resistance: the ability to withstand contact with specified
chemicals without a significant change in
Chimney: stone, masonry, prefabricated
metal or wood-framed structure, containing one or more flues, projecting
through and above the roof.
(CPE): a thermoplastic material, used for single-ply roof
membranes, composed of high molecular weight polyethylene that has been
chlorinated with a process that yields a flexible rubber-like
Chlorosulfonated polyethylene (CSPE or CSM):
probably best known by the DuPont trade name Hypalon™, a synthetic,
rubber-like thermoset material, based on high molecular weight
polyethylene with sulphonyl chloride, usually formulated to produce a
self-vulcanizing membrane. Classified by ASTM Standard D
Cladding: a material used as the exterior wall
enclosure of a building.
Cleat: a continuous metal
strip, or angled piece, used to secure metal components (also see
Clerestory: an upward extension of enclosed
space created by carrying a setback vertical, wall (typically glazed) up
and through the roof slope. Two intersecting shed roofs on different
Clip: A non-continuous metal component or
angle piece used to secure two or more metal components together. (see
Clipped gable: a gable cutback near the peak
in a hip-roof form.
Closed-cut valley: a method of
valley application in which shingles from one side of the valley extend
across the valley while shingles from the other side are trimmed back
approximately 2 inches (51 mm) from the
Closure strip: a metal or
resilient strip, such as neoprene foam, used to close openings created by
joining metal panels or sheets and flashings.
tar: a dark brown to black colored, semi-solid hydrocarbon
produced by the distillation of coal. Coal tar pitch is further refined to
conform to the following roofing grade specifications:
pitch: a coal tar used as the waterproofing agent in dead-level
or low-slope built-up roof membranes and membrane waterproofing systems,
conforming to ASTM Specification D 450, Type I.
waterproofing pitch: a coal tar used as the dampproofing or
waterproofing agent in below-grade structures, conforming to ASTM
Specification D 450, Type II.
Coal tar bitumen: a
proprietary trade name for Type III coal tar used as the dampproofing or
waterproofing agent in dead-level or low-slope built-up roof membranes and
membrane waterproofing systems, conforming
to ASTM D 450, Type
Coal tar felt: a felt that has been saturated or
impregnated with refined coal tar.
Coal tar roof
cement: a trowelable mixture of processed coal tar base,
solvents, mineral fillers and/or fibers. Classified by ASTM Standard D
4022, “Coal Tar Roof Cement, Asbestos Container.”
peel surface texture: a surface showing a texture where nodules
and valleys are approximately the same size and shape. This surface is
acceptable for receiving a protective coating because of the roundness of
the nodules and valleys.
Coated base sheet: a coated
felt intended to be used as a base ply in a built-up or modified bitumen
Coated fabric: fabrics that have been
impregnated and/or coated with a plastic like material in the form of a
solution, dispersion hot-melt or powder. The term also applies to
materials resulting from the application of a preformed film to a fabric
by means of calendering.
Coated felt (Sheet): (1) an
asphalt felt that has been coated on both sides with harder, more viscous
asphalt; (2) a glass fiber felt that has been simultaneously impregnated
and coated with asphalt on both sides.
layer of liquid material applied to a surface for protection or
Cobwebbing: a phenomenon observed during
spray application characterized by the formation of web-like threads along
with the usual droplets leaving the spray gun
Code: a collection of laws (regulations,
ordinances or statutory requirements) adopted by governmental authority.
(see Building code and Model code.)
Coefficient of thermal
expansion: the coefficient of change in dimension of a material
per unit of dimension per degree change in
Cohesion: the molecular forces of
attraction by which the body of a material is held
Coil coating: the application of a finish to
a coil of metal using a continuous mechanical coating
Cold forming: the process of shaping metal
into desired profiles without the application of heat.
rolled: the process of forming steel into sheets, panels, or
shapes on a series of rollers at room temperature.
assembly: a roof assembly configured with the insulation below
the deck, not typically in contact with
the deck, allowing for a
ventilation space. The temperature of the roof assembly remains close to
the outside air temperature.
Color stability: the
ability of a material to retain its original color after exposure to
Column: in structures, a relatively long,
slender structural compression member such as a post, pillar or strut;
usually vertical which acts in (or near) the direction of its longitudinal
Combing ridge: a term used to describe an
installation of finishing slate or wood at the ridge of a roof whereby the
slates on one side project beyond to the apex of the
Combustible: capable of
Combustion: a chemical process of oxidation
that occurs at a rate fast enough to produce heat and usually light either
as glow or flames; the process of burning.
materials: two or more substances that can be mixed, blended, or
attached without separating, reacting, or affecting the materials
Composition shingle: a unit of asphalt
Composite board roof insulation:
rigid board insulation generally comprised of perlite or wood fiberboard
factory bonded to polyisocyanurate or polystyrene.
thermoplastics: a category of roofing membranes made by blending
thermoplastic resins with plasticizers, various modifiers, stabilizers,
flame retardants, UV absorbers, fungicides and other proprietary
alloyed with proprietary organic
Compressive strength: the property of a
material that relates to its ability to resist compression loads.
Concealed-nail method: a method roofing application
in which all nails are driven into the underlying course of roofing and
covered by a subsequent, overlapping course.
plate: see Cover plate.
Condense: to make
denser or more compact, as when a material (e.g., water vapor) changes
from its gas phase to its liquid phase.
the liquid resulting from the condensation of a
Condensation: the conversion of water vapor or
other gas to liquid phase as the temperature drops; the act or process of
Conditioning: the storage of a material
specimen under specified temperature, humidity, etc. for a specified time
prior to testing.
Conductance, Thermal: the thermal
transmission in unit time through unit area of a particular body or
assembly having defined surfaces, when unit average temperature difference
is established between the surfaces.
Conductor head: an enlargement or catch
basin at the top of a downspout or leader to receive rainwater from a
gutter or scupper.
Construction joint: (1) a joint
where two successive placements of concrete meet; (2) a separation
provided in a building which allows its component parts to move with
respect to each other.
Contact cements: adhesives used
to adhere or bond various roofing components. These adhesives adhere mated
components immediately on contact of surfaces to which the adhesive has
Contamination: the process of making a
material or surface unclean or unsuited for its intended purpose, usually
by the addition or attachment of undesirable foreign
Control joint: a groove which is formed,
sawed, or tooled in a concrete or masonry structure to regulate the
location and amount of cracking and separation resulting from the
dimensional change of different parts of the structure, thereby avoiding
the development of high stresses.
Coping: the covering
piece on top of a wall exposed to the weather, usually made of metal,
masonry, or stone and sloped to carry off
Copolymer: the product of polymerization of two
or more substances (as two different isomers)
Copolymerization: a chemical reaction that
results in the bonding of two or more dissimilar monomers to produce
large, long-chain molecules that are
Copper: a natural weathering metal used in
metal roofing or flashing; typically used in 16 ounce per square foot
(0.56 mm) and 20 ounce per square foot (0.69 mm)
Core cut or core sample: (1) a sample
from a low-slope roof system taken for the purpose of obtaining primarily
qualitative information about its construction. Typically, core cut
analysis can verify or reveal the type of membrane surfacing; the type of
membrane; the approximate number of plies; the type, thickness and
condition of the insulation (if any); and the type of deck used as a
substrate for the roof system. (2) for in SPF-based roof systems, core
cuts are used to obtain both quantitative and qualitative information,
such as the thickness of the foam, the thickness and adhesion of the
coating, thickness of individual passes and adhesion between passes and
the adhesion of the foam to its substrate.
the decorative horizontal molding or projected roof
Counter batten: vertical wood strips
installed on sloped roofs over which horizontal battens are secured. The
primary roof covering is attached or secured to these horizontal
Counterflashing: formed metal or elastomeric
sheeting secured on or into a wall, curb, pipe, rooftop unit or other
surface, to cover and protect the upper edge of a base flashing and its
Course: (1) the term used for a
row of roofing material that forms the roofing, waterproofing or flashing
system; (2) one layer of a series of materials applied to a surface (e.g.,
a five-course wall flashing is composed of three applications of roof
cement with one ply of felt or fabric sandwiched between two layers of
Cover board: an insulation board used
over closed cell plastic foam insulation (e.g., polyisocyanurate) to
prevent blistering when used in conjunction with hot bituminous membranes.
Suitable cover board insulation are glassfaced siliconized gypsum board,
glass-fiber board, perlite board, wood-fiber board or mineral-fiber board.
Cover boards are also recommended between polyisocyanurate insulation and
single ply membranes to protect the polyisocyanurate.
plate: a metal strip sometimes installed over or under the joint
between formed metal pieces.
Coverage: the surface
area uniformly covered by a specific quantity of a particular material at
a specific thickness.
Crack: a nonlinear separation or fracture
occurring in a material.
Cream time: time in seconds
(at a given temperature) when the A and B components of polyurethane foam
will begin to expand after being mixed. Recognizable as a change in color
of the materials.
Cricket: a relatively small area of
a roof constructed to divert water from a horizontal intersection of the
roof with a chimney, wall, expansion joint or other projection. (see
Cross-linking: the formation of chemical
bonds between polymeric chains. Cross-linking of rubber is referred to as
vulcanization or “curing.”
CRREL: Cold Regions
Research and Engineering Laboratory.
waterproofing: a compound of cement, quartz or silica sand, and
other active chemicals that are mixed and packaged for use in a dry powder
form; the packaged mixture is then mixed with water and applied to a
concrete surface where it penetrates into the pores of
Cupola: a relatively small roofed
structure, generally set on the ridge or peak of a main roof area for
ventilation or aesthetic purposes.
Curb: (1) a raised
member used to support roof penetrations, such as skylights, mechanical
equipment, hatches, etc. above the level of the roof surface; (2) a raised
roof perimeter relatively low in height.
process whereby a material is caused to form permanent molecular linkages
by exposure to chemicals, heat, pressure and/or
Cure time: the time required for a
material to reach its desirable long-term physical
Cured concrete: concrete that has
attained its intended design performance properties.
agent: an additive in a coating or adhesive that results in
increased chemical activity between the components with an increase or
decrease in rate of cure.
Curing compound: a liquid
that is sprayed or otherwise applied to newly placed concrete which
retards the loss of water during curing.
solvent-thinned bitumen used in cold-process roofing adhesives, roof
cements and roof coatings.
Cutoff: a permanent detail
designed to prevent lateral water movement in an insulation system and
used to isolate sections of a roofing system. (Note: A cutoff is different
from a tie-in, which may be a temporary or permanent seal.) (see
Cutout: the open portions of a strip shingle
between the tabs. Sometimes referred to as a keyway.
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Dampproofing: treatment of a surface or
structure to resist the passage of water in the absence of hydrostatic
Dead level: absolutely horizontal or zero
slope. (see Slope.)
Dead-level asphalt: see
Dead loads: the weight of a structure itself,
including the weight of fixtures or equipment permanently attached to
Deck: a structural component of the roof of a
building. The deck must be capable of safely supporting the design dead
and live loads, including the weight of the roof systems, and the
additional live loads required by the governing building codes and provide
the substrate to which the roofing or waterproofing system is applied the
structural surface of a building to which a roof assembly is installed.
Decks are either non-combustible (e.g., corrugated metal, concrete, or
gypsum) or combustible (e.g., wood plank or
Deflection (bowing, sagging): (1) the
deformation of a structural member as a result of loads acting on it; (2)
any displacement in a body from its static position, or from an
established direction or plane, as a result of forces acting on the
Degradation: a deleterious change in the
chemical structure, physical properties or appearance of a material from
natural or artificial exposure (e.g., exposure to radiation, moisture,
heat, freezing, wind, ozone, oxygen, etc.).
days: a unit used in estimating the fuel consumption for a
building; equal to the number of degrees that the mean temperature, for a
24-hour day, is below the “base temperature”; the base temperature is
taken as 65° F (18.3° C) in the U.S.A.
separation of the laminated layers of a component or
Design loads: the total load on a structural
system for the most severe combination of loads and forces which it is
designed to sustain.
Dew-point temperature: the
temperature at which air becomes saturated with water vapor. The
temperature at which air has a relative humidity of
Diaphragm: a floor slab, metal wall panel, roof
panel, or the like, having a sufficiently large in-plane shear stiffness
and sufficient strength to transmit horizontal forces to resisting
Diffusion: the movement of water vapor from
regions of high concentration (high water vapor pressure) toward regions
of lower concentration.
Dimensional shingle: a shingle
that is textured, overlayed, or laminated and designed to produce a
three-dimensional effect. (also see Laminated shingle and Architectural
Dimensional stability: the degree to which a
material maintains its original dimensions when subjected to changes in
temperature and humidity.
DOE: U.S. Department of
Dormer: a structure projecting from a sloping
roof usually housing a window or ventilating louver.
coverage: application of asphalt, slate, or wood roofing such
that the lapped portion is at least 2 inches (50 mm) wider than the
exposed portion, resulting in two layers of roofing material over the
Double lock standing seam: in a metal roof panel
or metal cap, a standing seam that uses a double overlapping interlock
between two metal panels. (see Standing seam.)
pour: to apply two layers or flood coats of bitumen and aggregate
to a built-up roof.
Downspout: a vertical pipe or
conduit used to carry runoff water from a scupper, conductor head or
gutter of a building to a lower roof level or to the ground or storm water
Drag load: the external force (e.g.,
from the weight of ice and snow) applied to a steep-slope roof system
component forcing the component downslope.
outlet or other device used to collect and direct the flow of runoff water
from a roof area.
Drip edge: a metal flashing or other
overhanging component with an outward projecting lower edge, intended to
control the direction of dripping water and help protect underlying
Dry: free or relatively free from
a liquid, especially water; (2) to remove water or
Dry bulb temperature: the temperature of air
as measured by an ordinary thermometer.
thickness: the thickness, expressed in mils, of an applied and
cured coating or mastic. For comparison, see Wet film
Drying time: the time required for the loss
of volatile components so that the material will no longer be adversely
affected by weather conditions such as dew, rain, or
Dual level drain: in waterproofing, an
outlet or other device with provisions for drainage at both the wearing
surface and waterproofing membrane levels used to collect and direct the
flow of runoff water from a horizontal slab.
any load which is nonstatic, such as a wind load or moving live
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Eave: the lower edge of a sloping roof
that part of a roof which projects beyond the wall.
height: the vertical dimension from finished grade to the
ECH: polyepichlorohydrin, commonly referred to
as epichlorohydrin. (see Epichlorohydrin.)
stripping: membrane flashing strips cut to specific widths used
to seal/flash perimeter edge metal and the roof membrane application of
felt strips cut to narrower widths than the normal felt-roll width to
cover a joint between metal perimeter flashing and built-up
Edge venting: the practice of providing
regularly spaced or continuously protected (e.g., louvered) openings along
a roof edge or perimeter, used as part of a ventilation system to
dissipate heat and moisture vapor.
encrustation of soluble salts, commonly white, deposited on the surface of
stone, brick, plaster, or mortar; usually caused by free alkalies leached
from mortar or adjacent concrete as moisture moves through
Elasticity: the property of a body that
causes it to tend to return to its original shape after deformation (as
stretching, compression or torsion).
macromolecular material that returns rapidly to its approximate initial
dimensions and shape after substantial deformation by a weak stress and
subsequent release of that stress.
coating: a coating that is capable of being stretched at least
twice its original length (100 percent elongation) and recovering to its
Elongation: the ratio of the
extension of a material to the length of the material prior to
Embedment: (1) the process of
pressing/positioning a felt, aggregate, fabric, mat, or panel into hot
bitumen or adhesive to ensure intimate contact at all points; (2) the
process of pressing/positioning granules into coating in the manufacture
of factory-prepared roofing, such as
Embrittlement: the loss of flexibility or
elasticity of a material.
Emulsion: A mixture of
bitumen and water, with uniform dispersion of the bitumen or water
globules, usually stabilized by an emulsifying agent or
End lap: the distance of overlap where one
ply, pane, or piece extends beyond the end of the immediately adjacent
underlying ply, panel, or piece.
(Bitumen-stop): a continuous membrane edge seal formed at the
perimeter and at penetrations by folding the base sheet or ply over the
plies above and securing it to the top of the membrane. The envelope
prevents bitumen seepage from the edge of the
EPDM: Ethylene propylene diene monomer (see
also Ethylene propylene diene terpolymer.)
(ECH): a synthetic rubber including two epichlorohydrin based
elastomers. It is similar to and compatible with
Epoxy: a class of synthetic, thermosetting
resins that produce tough, hard, chemical-resistant coatings and
Equilibrium moisture content (EMC): (1) the
moisture content of a material stabilized at a given temperature and
relative humidity, expressed as percent moisture by
Equiviscous temperature (EVT): the temperature
at which a bitumen attains the proper viscosity for built-up membrane
Equiviscous temperature (EVT) application
range: the recommended bitumen application temperature range. The
range is approximately 25° F (14° C) above or below the EVT, thus giving a
range of approximately 50° F
(28° C). The EVT range temperature is
measured in the mop cart or mechanical spreader just prior to application
of the bitumen to the substrate.
Equiviscous temperature (EVT)
for asphalt: the recommended EVT for roofing asphalt (ASTM D 312,
Type I, II, III or IV) is as follows:
application: the temperature at which the asphalt’s apparent
viscosity is 125 centipoise (0.125 Pa•s).
spreader application: the temperature at which the asphalt’s
apparent viscosity is 75 centipoise (0.075 Pa•s).
Note: In order to
avoid the use of two kettles if there are simultaneous mop and mechanical
spreader applications, the EVT for mechanical spreader application can be
used for both application techniques.
(EVT) for coal tar: the recommended EVT for roofing coal tar
(ASTM D 450, Type I or III) is the temperature at which the coal tar’s
apparent viscosity is 25 centipoise (0.025 Pa•s).
interpolymers (EIP): a group of thermoplastic compounds generally
based on PVC polymers from which certain single-ply roofing membranes can
Ethylene propylene diene terpolymer
(EPDM): designated nomenclature of ASTM for a terpolymer of
ethylene, propylene and diene. EPDM material is a thermosetting synthetic
Exhaust ventilation: air that is vented
or exhausted from the roof cavity, typically through vents installed on
the up slope portion of the roof. For example, with most steep-slope roof
assemblies, exhaust vents are typically located at or near the
Exotherm: heat generated by a chemical
Expansion cleat: a cleat designed to
accommodate thermal movement of metal roof panels.
joint: a structural separation between two building elements that
allows free movement between the elements without damage to the roofing or
Exposed-nail method: a method of
asphalt roll roofing application in which all nails are driven into the
adhered, overlapping course of roofing. Nails are exposed to the
Exposure: (1) the traverse dimension of a
roofing element or component not overlapped by an adjacent element or
component in a roof covering. For example, the exposure of any ply in a
built-up roof membrane may be computed by dividing the felt width, minus 2
inches (51 mm), by the number of shingled plies; thus, the exposure of 36
inch (914 mm) wide felt in a shingled, four-ply membrane should be
approximately 81/2 inches (216 mm) (See Figure 8); (2) the dimension of
sidewall or roofing covering that is not covered or overlapped by the up
slope course of component. The typical exposure for a standard-sized,
three-tab shingle is 5 inches (127 mm), depending on manufacturer
Extrusion: a process in which heated
or unheated material is forced through a shaping orifice (a die) in one
continuously formed shape, as in film, sheet, rod or
Eyebrow: a dormer, usually of small size,
whose roof line over the upright face is typically an arched curve,
turning into a reverse curve to meet the horizontal at either end. Also, a
small shed roof projecting from the gable end of the larger, main roof
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Fabric: a woven cloth or material of
organic or inorganic filaments, threads, or yarns used for reinforcement
in certain membranes and flashings.
Factory Mutual Research
(FMR): commonly referred to as "F," a research and testing
organization that classifies roofing components and assemblies for their
fire, traffic, impact (hail), weathering, and wind-uplift resistance for
four major insurance companies in the United States.
seam: splice/seam made by the manufacturer during the assembly of
sections of materials into larger
fading: any lightening of initial
Fallback: a redution in bitumen softening
point, sometimes caused by refluxing or overheating in a relatively closed
container.(See Softening Point Drift.)
Fascia: (1) in
steep-slope roofing, a board that is nailed to the ends of a roof rafter;
sometimes supports a gutter;(2) in low-slope roofing, the vertical or
steeply sloped roof or trim located at the perimeter of a building.
Typically, it is a border for the low-slope roof
Feathering strips: tapered wood filler strips
placed along the butt ends of old wood shingles to create a relatively
smooth surface when reroofing over existing wood shingle roofs. Referred
to in some regions of the country as "horse feathers,: or leveling
Felt: a flexible sheet manufactured by the
interlocking of fibers with a binder or through a combination of
mechanical work, moisture and heat. Felts are manufactured principally
from wood pulp and vegetable fibers (organic felts), asbestos felts),
glass fibers (glass fiber felts or ply sheets), or polyester
Felt machine (Felt Layer): a menchanical
device used for applying bitumen and roofing felt or ply sheet
Ferrule: a metal sleeve placed inside
a gutter at the top. A spike or screw is nailed/screwed through the gutter
face and ferrule into the fascia board to hold the gutter in place. The
ferrule acts as a spacer in the gutter to maintain its original
Field seam: a splice or seam made in the field
(not factory) where overlapping sheets are joined together using an
adhesive, splicing tape, or heat- or
Filler: a relatively inert ingredient
added to modify physical characteristics.
heavy bead of waterproofing compound or sealant material generally
installed at the point where vertical and horizontal surfaces meet; to
reduce the desired effet to take out the 90° angle at the base of a
Film: sheeting having a nominal
thickness not greater than 10 mils (0.25 mm).
thickness: the thickness of a membrane or coating. Wet film
thickness is the thickness of a coating as applied; dry film thickness is
the thickness after curing. Film thickness is usually expressed mils
(thousandths of an inch).
Fin: a term used to describe
a deck surface condition. A sharp raised edge (generally in concrete)
capable of damaging a roof membrane or vapor retarder.
mineral-surfacing: water-insoluble, inorganic material, more than
50 percent of which passes through a No.35 sieve. Used on the surface of
various roofing materials and membranes to prevent
Fire resistance: the property of a material
or assembly to withstand fire or give protection from it.
retardant treated (FRT) plywood: plywood which has been
impregnated, under pressure, with mineral salts; in the event of fire, the
burning wood and salts emit noncombustible gases and water vapor instead
of the usual flammable vapors.
referred to as an edge wrinkle) (1)a half-cylindrical or half-conical
shaped opening or void in a lapped edge or seam, usually caused by
wrinkling or shifting of ply sheets during installation; (2) in shingles,
a half-conical opening formed at a cut edge.
in protective coatings, the detachment of small pieces of the coating
Flammable: subject to easy ignition and rapid
Flame retardant: a chemical used
to impart flame resistance.
Flame spread: the
propagation of a flame away from its source of
Flammability: those characteristics of a
material that pertain to its relative ease of ignition and ability to
Flange: the projecting edge of a
rigid or semi-rigid component, such as a metal edge flashing
Flash point: the lowest temperature at which
vapors above a volatile combustible substance ignite in air when exposed
to a flame. Flashing: components used to weatherproof or
seal roof system edges at perimeters, penetrations, walls, expansion
joints, valley, drains and other places wheere the roof covering is
interrupted or terminated. For example, membrane base flashing covers the
edge of the field membrane, and cap flashings or counterflashings shield
the upper edges of the base flashing.
a trowelable mixture of solvent-based bitumen and mineral stabilizers that
may include asbestos or other inorganic or organic fibers. Generally,
flashing cement is characterized as vertical-grade, which indicates it is
intended for use on vertical surfaces, (se Asphalt Roof Cement and Plastic
Flashing collar: (somtimes referred to as a
roof jack or flashing boot) an accessory flashing used t cover and/or seal
soil pipe vents and other penetrations through the roof.
lock: a method of interlocking metal panels in which one panel
edge is folded back on top of itself and the other panel is folded under,
after which the two panels are hooked
Fleece: mats or felts composed of fibers,
sometimes used as a membrane backer.
coat: the surfacing layer of bitumeninto which surfacing
aggregateis embedded on an aggregate surfaced built-up
Flood test: the procedure in which a controlled
amount of water is temporarily retained over a horizontal surface to
determine the effectiveness of the waterproofing
Fluid-applied elastomer: a liquid elastomeric
material that cures after application to form a continuous waterproofing
Fly-in: method of application for roll
materials by which the dry sheet is set into the bitumen or adhesive
applied to the roof surface.
FM: see Factory Mutual
Foam stop: the roof edge treatment
upon which SPF is terminated.
Force: a strength or
energy exerted or brought to bear; cause of motion or
FPL: Forest Products
Froth pack: a term used to describe small,
disposable aerosol cans that contain SPF components. Two component froth
packs are available to do small repairs for sprayed polyurethane
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G90: a designation for galvanized metal
sheet, indicating 0.90 ounces (26 g) of zinc per square foot, measured on
Gable: the verticle triangular portion of
the end of a building having a double-sloping roof, from the level of the
eaves to the ridge of the roof.
Gable roof: a
single-ridge roof that terminates at gable
Galvalume: trade name for a metal alloy
coating that is composed of aluminum, zinc and
Galvanic action: an electrochemical action
that generates electical current between two metals of dissimilar
Galvanic series: a list of metals
and alloys arranged according to their relative electrolytic potentials in
a given environment.
Galvanized: to coat steel or iron
Galvanized steel: steel coated with zinc
for corrosion resistance.
Gambrel: a roof that has two
pitches on each side, where the upper roof area has less slope than the
lower roof areas.
Gauge: a roof that has two pitches
on each side, where the upper roof area has less slope than the lower roof
Geocomposite: a prefabricated water drainage
material used to relieve hydrostatic pressure against waterproofing and
Geotextile: a tightly woven fabric
used to restrict the flow of fine soil particles and other contaminants
while allowing water to pass freely through; used to protect drainage
systems from clogging.
Girt: a horizontal beam that
supports wall cladding between columns.
insulation: blanket or rigid board insulation, composed of glass
fibers bound together with a binder, faced or unfaced, used to insulate
roofs and walls.
Glass felt: glass fibers bonded into
a sheet with resin and suitable for impregnation with asphalt in the
manufacture of bituminous waterproofing, roofing membranes and
Glass mat: a thin mat of glass fibers with
or without a binder.
Glaze coat: (1) the top layer of
asphalt on a smooth-surfaced built-up roof membrane; (2) a thin protective
coating of bitumen applied to the lower plies or top ply of a built-up
roof membrane when application of additional felts or the flood coat and
aggregate surfacing are delayed. (also see Flood
Gloss: the shine, sheen or luster of a dried
Grain: a unit of measure in the English System
of units; 7,000 grains equals 1 lb.; used as a measure of the weight of
moisture in air.
Granule: (also referred to as mineral
or ceramic granule) opaque, natural or synthetically colored aggregate
commonly used to surface cap sheets, shingles, and other granule-surfaced
Gravel: coarse granular aggregate
resulting from the natural erosion of rock.
stop: a flanged device, frequently metallic, designed to prevent
loose aggregate from washing off the road and to provide a continuous
finished edge for the roofing.
Groundwater level: at a
particular site, the level, below which the subsoil and rock masses of the
earth are fully saturated with water.
Grout: a mixture
of cement, sand, and water used to fill cracks and cavities in
Gusset: used at the bottom of a steep-slope
roof system valley, a large flat metal piece(s) wider than the valley to
help prevent build-up at the base of the valley, either from debris or ice
Gutter: a channeled component
installed along the downslope perimeter of a roof to convey runoff water
from the roof to the drain leaders or downspouts.
panels: cementitious board stock with noncombustible core
primarily comprised of gypsum that is commonly used as a barrier board
thermal barrier or cover board in a roof assembly.
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Hand-tabbing method of spot applying
asphalt-based adhesive to shingles for securement and wind
Headlap: the distance of overlap measured
from the uppermost ply or course to the point where it laps over the
undermost ply or course.
Heat flow: the quantity of
heat transferred to or from a system in a unit of time.
seaming: the process of joining thermoplastic films, membranes,
or sheets by heating and then applying pressure to bring both materials in
contact with each other. (see Heat welding.)
transfer: the transmission of thermal energy from a location of
higher temperature to a location of lower temperature. This can occur by
conduction, convection or radiation.
method of melting and fusing together the overlapping edges of separate
sheets or sections of polymer modified bitumen, thermoplastics or some
uncured thermoset roofing membranes by the application of heat (in the
form of hot air or open flame) and pressure. (see Heat
Hem the edge created by folding metal back
Hip: the inclined external angle formed by
the intersection of two sloping roof planes.
a roof that rises by inclined planes to form one or more
Hoist: a mechanical lifting
Holiday: an area where a liquid-applied
material is missing or absent.
Honeycomb: voids left
in concrete resulting from failure of the mortar to effectively fill the
spaces among coarse aggregate particles.
Hot or Hot
stuff: a roofing worker's term for hot
Hue: the subjective perception of color such
as red, yellow, green, blue, purple or some combination; white black or
gray possess no hue.
Humidity: the condition of the
atmosphere with respect to water vapor. See relative
HVAC heating, ventilating, and air condition
Hybrid roof covering: combination of two or
more separate and distict roof membranes; e.g. three ply smooth BUR and a
modified bitumen cap.
Hydration: the chemical reaction
by which a substance (such as Portland cement) combines with water, giving
off heat to form a crystalline structure in its setting and
Hydrocarbon: an organic chemical compound
primarily containing the elements carbon and
Hydrostatic pressure: the pressure
equivalent to that exerted on a surface by a column of water of a given
Hydrostatic pressure relief system: a system
of perimeter and/or under slab drains used to regulate the hydrostatic
pressure in the earth surrounding a below-grade
Hygroscopic: attracting, absorbing and
retaining atmospheric moisture.
registered trademark of E.I. du Pont de Nemours & Co., for
"chlorosulfonated polyethylene" (CSPE). (see Chlorosulfonated
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ICBO: International Conference of Building
Ice dam: a mass of ice formed at the
transisiton from a warm to a cold roof surface, frequently formed by
refreezing meltwater at the overhang of a steep roof, causing ice and
water to back up under roofing materials.
Ice dam protection
membrane: a continuous membrane installed under steep slope
roofing materials in areas subject to ice damming that prohibits water
which gets through the roof covering from getting into the structure. Must
also seal the fasteners that penetrates it.
temperature: the lowest temperature at which combustion will
occur spontaneously under specific conditions.
resistance: resistance to fracture under the sudden application
of an exerted force.
Impregnate: In roofing materials
manufacture, to completely surround the fibers in a felt or mat with
bitumen, with the spaces between the fibers partially or completely filled
without a continuous coating of bitumen on the
Infrared thermography: The process of
displaying variations of apparent temperatures (variation of temperature
or emissivity or both) over the surface of an object by measuring
variations in infrared radiance.
Inorganic: being or
composed of materials other than hydrocarbons and their derivatives, or
matter that is not of plant or animal origin.
screen: wire mesh used to prevent insects from entering the
building through ventilators, louvers, or other
In-service R-value: thermal resistance value
established under installed conditions and measured over the expected
service life of the material.
Insulation: any of a
variety of materials designed to reduce the flow of heat, either from or
into a building. (see also Thermal insulation.) Intake
ventilation: the fresh air that is drawn into a passive
ventilation system through vents typically installed in the soffit or eave
of a roof.
Interlayment: a felt, metal, or membrane
sheet material used between courses of steep-slope roofing to improve the
weather- and water-shedding characteristics of the primary roof covering
during times of wind-driven percipitation. Typically used with wood
Interlocking shingles: individual shingles
that mechanically attach to each other to provide enhanced wind resistance
without reliance on sealing strips.
Inverted roof membrane
assembly (IRMATM): a patented, proprietary variation of the
“protected membrane roof assembly” in which Styrofoam® brand insulation
and ballast are placed over the roof membrane. IRMATM and Styrofoam® are
registered trademarks of the Dow Chemical
ISANTA: International Staple, Nail & Tool
Isocyanate: a highly reactive organic
chemical containing one or more isocyanate (-N=C=O) groups. A basic
component in SPF based systems and some polyurethane coating
Isolation sheet: refer to slip sheet.
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Joist: any of the small timbers, metal or
wood beams arranged parallel to each other and spanning from wall to wall
to support a floor, ceiling, or roof of a
Joule: a unit of energy or work; equals the
work done by a force of 1 newton which acts over a distance of 1 meter in
the direction of the force.
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k or k-Value: thermal conductivity; the
time rate of heat flow through a unit area of a homogeneous material in a
direction perpendicular to isothermal planes induced by a unit temperature
gradient. In English (inch-pound) units of measurement, it is the number
of BTUS that pass through a 1 inch (25 mm) thinckness of a 1 square foot
(0.09 m2) sample of material in 1 hour with a temperature difference
between the two surfaces of 1°F. It is expressed as
Kerf: (1) a slit or notch made by a
saw or cutting torch; (2) the width of cut made by a saw or cutting
Kesternich test:simulates acid rain conditions
by subjecting test specimens to a sulfur dioxide atmosphere as well as
condensing moisture for the purpose of evaluating rust/corrosion
Knee cap: a metal cover trim that
fits over a panel rib after it has been cut and bent.
joints: see Knuckle.
Knuckle: a metal
closure, either shop-or pre-fabricated, installed over the cut seam of a
continuous metal roof panel at the transition from a steep-slope roof to a
vertical roof or wall.
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Laitance: a weak layer of cement and
aggregate fines on a concrete surface that is usually caused by an overwet
mixture, overworking the mixture, improper or excessive finishing or
Laminate: to join layers of
materials together using fusion; the process of joining layers of
materials together using adhesion.
see Dimensional shingles or Architectural
Lap: that part of a roofing, waterproofing,
or flashing component that overlaps or covers any portion of the same or
another type of adjacent component.
Lap cement: an
asphalt-based roof cement formulated to adhere overlapping plies or
asphalt roll roofing.
Lap seam: occurs where
overlapping materials are seamed, sealed or otherwise
Latex: a stable dispersion of polymeric
substance in an essentially aqueous medium.
soft malleable, heavy metal; has low melting point and a high coefficient
of thermal expansion.
Leader head: see Conductor
Lift: the sprayed polyurethane foam that results
from a pass. It usually is associated with a certain pass thickness and
has a bottom layer, center mass and top skin in its
Liquid-applied: application of bituminous
cements, adhesives or coating installed at ambient or slightly elevated
Liquid-applied built-up roof: a
continuous, semi-flexible roof membrane, consisting of multiple plies of
felts, mats or fabrics laminated together with alternate layers of roof
cements andd surfaced with a liquid-applied coating with or without
Live loads: temporary loads that
the roof structure must be designed to support, as required by governing
building codes. Live loads are generally moving and/or dynamic or
environmental, (e.eg., people, installation equipment, snow, ice or rain,
Loose-laid membrane: a ballasted roofing
membrane that is attached to the substrate only at the edges and
penetrations through the roof.
Low-slope roofs: a
category of roofs that generally include weatherproof membrane typesof
roof systems installed on slopes at or less than 3:12 (14
Low temperature flexibility: the ability of
a membrane or other material to resist cracking when flexed after it has
been cooled to a low temperature.
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Mansard: a decorative steep-sloped roof on
the perimeter of a building.
Mansard roof: a steeper
roof that terminates into a flat roof at its high
Masonry: construction, usually set in mortar,
of natural building stone or manufactured units, such as brick, concrete
block, adobe, glass block, tile, manufactured stone or gypsum
Mastic: a thick adhesive material used as a
cementing agent for holding waterproofing membrane in place. (see Asphalt
Mat: a thin layer of woven, non-woven,
or knitted fiber that serves as reinforcement to a material or
Mat slab: a concrete slab designed with
reinforcement to resist the uplift forces created by hydrostatic
Material safety data sheets (MSDS): a
written description of the chemicals in a product and other pertinent
data, including such things as safe handling and emergency procedures. In
accordance with OSHA regulations, it is the manufacturer's responsibility
to produce an MSDS and the employers responsibility to communicate its
contents to employee.
Mechanical damage: in SPF-based
roofing, physical damage to a completed SPF-based roof system not caused
by normal wear and tear.
membranes: generally used to describe membranes that have been
attached at defined intervals to the
Membrane: a flexible or semi-flexible roof
covering or waterproofing whose primary function is to exclude
Metal: any of various opaque, fusible, ductile
and typically lustrous substances that are good conductors of electricity
Metallic waterproofing: consists of finely
graded iron particles combined with an oxidizing catalyst. When mixed with
water (or water, cement, and sand), the finely distributed particles
expand, creating a waterproof layer that becomes a part of the surface to
which it is applied.
Metal rain collar: a metal
counterflashing used to wrap a penetration and prevent water infiltration
through the top of the penetration base
Meter: unit of length measurement in the
metric system: 1 meter is equal to 39.37 inches.
panel: an interlocking metal sheet having a minimum installed
weather exposure of less than 3 square feet (279000 mm2 or 0.28 m2) per
Mil: a unit of measure, one mil is equal to
0.001 inches, or 25.4 micrometers (µm), often used to indicate the
thickness of a roofing membrane.
Mildew: a superficial
growth produced on organic matter or living plants by
Millimeter: a unit of measure equal to one
thousandth (0.001) of a meter, or 0.03937 inches.
fiber: insulation composed principally of fibers manufactured
from rock, slag or glass, with or without binders.
granules: see Granules.
Mineral stabilizer: a
fine, water-insoluble inorganic material, used in a mixture with solid or
semi-solid bituminous materials.
roofing: roofing materials whose surface or top layer consists of
a granule-surfaced sheet.
Miner-surfaced sheet: a
roofing sheet that is coated on one or both sides with asphalt and
surfaced with mineral granules.
Miter joint: a joint
between two members at an angle to each other; each member is cut at an
angle equal to half the angle of the junction; usually the members are at
right angles to each other.
Model (building) codes: a
compilaton of standards or codes established to provide uniformity in
regulations pertaining to building construction.
bitumen: (1) a bitumen modified by including one or more polymers
(e.g., atactic polypropylene, styrene butadiene styrene, etc.); (2)
composite sheets consisting of a polymer modified bitumen often reinforced
with various types of mats or films and sometimes surfaced with films,
foils or mineral granules.
Moisture contour map: a map
used to graphically define the location of moisture within a roof assembly
after a moisture scan has been performed.
vent: a venting device installed through the roofing membrane to
relieve moisture vapor pressure from within the roofing
Moisture scan: the use of a mechanical device
(capacitance, infrared, or nuclear) to detect the presence of moisture
within a roof assembly. (see Non-destructive testing.)
run: a meandering ridge in a roof membrane not associated with
insulation or deck joints.
Monolithic: formed from or
composed of a single material; seamless.
low-molecular-weight substance consisting of molecules capable of reacting
with like or unlike molecules to form a
Mop-and-flop: an application procedure in
which roofing elements (insulation boards, felt plies, cap sheets, etc.)
are initially placed upside down adjacent to their ultimate locations;
coated with adhesive or bitumen; and turned over and adhered to the
Mopping: the application of hot bitumen
with a mop or mechanical applicator to the substrate or plies of a
bituminous membrane. There are four types of
·Solid mopping: bitumen is applied in
·Spot mopping: bitumen is
applied roughly in circular areas, leaving a grid of unmopped
·Sprinkle mopping: bitumen
is shaken onto the substrate from a broom or mop in a random
·Strip mopping: bitumen is applied in
Mud cracking: surface cracking
resembling a dried mud flat.
Mud slab: a layer of
concrete, typically 2 inches (50 mm) to 6 inches (150 mm) thick, used as
the substrate for membrane waterproofing.
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Nailer: (sometimes referred to as
blocking) a piece or pieces of dimensional lumber and/or plywood secured
to the structural deck or walls, which provide a receiving medium for the
fasteners used to attach membrane or flashing.
acrylonitrile butadiene polymer blend. One proprietary NBP membrane is
commonly referred to as nitrile butadiene copolymer.
side waterproofing: an application wherein the waterproofing
system and source of hydrostatic pressure are on opposite sides of the
Neoprene: a synthetic rubber
(polychloroprene) used in liquid and sheet-applied elastomeric roof
membranes or flashings.
Nesting: (1)the installation
of new metal roof deck directly on top of existing metal roof deck; (2) a
metod of reroofing with new asphalt shingles over existing shingles in
which the top edge of the new shingle is butted against the bottom edge of
the existing shingle.
Net free vent area: the area
(measured in square inches) open to unrestricted air flow and commonly
used as a yardstick to measure relative vent performance; the area of the
opening of a vent minus the area displaced by the screening
Newton (N): SI unit of measure for
Night seal (or night tie-in): a material and/or
method used to temporarily seal a membrane edge during construction to
protect the roofing assembly in place from water penetration. Usually
removed when roofing application is resumed.
National Institute of Standards and Technology
alloy: an elastomeric material of synthetic nonvulcanizing
Nitrile rubber: a membrane whose predominant
resinous ingredient is a synthetic rubber made by the polymerizaton of
acrylonitrile with butadiene.
Noble metal: a metal
that readily receives electrons from an anodic metal (see Galvanic
No-cutout shingles: shingles consisting of a
single solid strip with no cutouts.
(NDT): a method to evaluate the disposition, strength or
composition of materials or systems without damaging the object under
test. Typically used to evaluate moisture content in roofing assemblies,
the three common test methods are electrical capacitance, infrared
thermography and nuclear back-scatter.
not easily ignited and not burning rapidly if
Nonfriable: a material that, when dry, cannot
be crumbled, pulverized or reduced to powder by hand
Nonoxidizing: a material which resists
oxidation in exterior exposures or accelerated
Non-traffic bearing: for waterproofing
purposes, a membrane system requiring some form of protection barrier and
Nonvolatile content: the portion of a
coating that does not evaporate during drying or curing under specified
conditions, comprising the binder and, if present, the pigment. (The
percent volatile content is obtained by subtracting the nonvolatile
content from 100.).
Nonwoven fabric: a textile
structure produced by bonding or interlocking of fibers, or both,
accomplished by mechanical, chemical, thermal, or solvent means and
NRCA: National Roofing
Nuclear hydrogen detection (NHD)
meter: a device that contains a radioactive source to emit high
velocity neutrons into a roof system. Reflecting neutrons are measured by
a gauge that is used to detect hydrogen; the quantity of hydrogen detected
may be linked to the pressure of water.
name for a famly of polyamide polymers, used as a scrim in some
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Off-ratio foam: SPF that has excess
isocyanate or resin. Off-ratio will not exhibit the full physical
properties of normal SPF.
Open time: the period of
time after an adhesive has been applied and allowed to dry, during which
an effective bond can be achieved by joining the two
Open valley: a method of valley construction
in which the steep-slope roofing on both sides are trimmed along each side
of the valley, exposing the metal valley flashing.
surface texture: in SPF roofing, a condition of the foam in which
the surface shows a fine texture and is compared to the exterior skin of
an orange. This surface is considered acceptable for receiving a
Organic: being or composed of
hydrocarbons or their derivatives, or matter of plant or animal
Organic felt: an asphalt roofing base material
manufactured from cellulose fibers.
an asphalt shingle reinforced with material manufactured from cellulose
ORNL: Oak Ridge National
osmosis: movement of a solvent through a
semipermeable membrane into a solution of higher solute concentration that
tends to equalize the concentration of solute on the two sides of the
Overflow drainage: component in a roof
drainage system used to protect the roof against damage from a water load
imposed by blocked or partially blocked primary drainage system; e.g.,
overflow scupper, overflow interior drain.
undesirable depositions of airborne spray.
texture: in SPF roofing, a condition of the foam in which the
surface shows a linear coarse textured pattern and/or a pebbled surface.
This surface is generally downwind of the sprayed polyurethane path and,
if severe, unacceptable for proper coating coverage and
Ozone: a triatomic form of oxygen that is
a bluish gas of pungent odor; is formed naturally in the upper atmosphere
by a photochemical reaction with solar ultraviolet radiation.
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Pallet: a platform (typically wooden) used
for storing and shipping materials.
Pan: the bottom
flat part of a roofing panel that is between the ribs of the
Pan former: power roll-forming equipment that
produces a metal roofing panel from a flat sheet.
wall: the part of a perimeter wall that extends above the
Parge: in masonry construction, a coat of cement
mortar on the face of rough masonry, the earth side of foundation and
basement walls, or the like.
Partially attached: a
roofing assembly in which the membrane has been “spot affixed” to a
substrate, usually with an adhesive or a mechanical
Parting agent: a material applied to one or
both surfaces of a sheet to prevent blocking.
SI unit of measure for force per unit area; 1
Pass: (1) a layer of material, usually
applied by the spray method, that is allowed to reach cure before another
layer (“pass”) is applied; (2) a term used to explain a spray motion of
the foam gun in the appliction of the spray polyurethane foam (SPF)
material. The speed of the pass controls the thickness of the
Pass line: the junction of two passes of SPF. A
distinct line is formed by the top skin of the bottom pass and the next
pass adhering to this skin.
Pedestal: a support or
base for roof top components such as pavers, pipes and small roof top
Peel strength: the average load per unit width
required to separate progressively a flexible member from a rigid member
or another flexible member.
Penetration: (1) any
construction (e.g., pipes, conduits, HVAC supports) passing through the
roof; (2) the consistency of a bituminous material expressed as the
distance, in tenths of a millimeter (0.1 mm), that a standard needle
penetrates vertically into a sample of material under specified conditions
of loading, time, and temperature.
aggregate used in lightweight insulating concrete and preformed perlitic
insulation boards, formed by heating and expanding siliceous volcanic
Permeability: (1)the capacity of a porous
material to conduct or transmit fluids; (2) the time rate of vapor
transmission through unit area of flat material of unit thickness induced
by unit vapor pressure difference between two specific surfaces, under
specified temperature and humidity conditions. The English (inch-pound)
unit of measurement for mpermeability is gr/hr·ft2(in.Hg/in.), which is
commonly referred to as “perm·inch” units.
(1) the rate of water vapor transmission per unit area at a steady state
through a material, membrane, or assembly; (2)the time rate of water vapor
transmission through unit area of flat material or constructon induced by
unit vapor pressure difference between two specific surfaces, under
specified temperature and humidity conditions. The English (inch-pound)
unit of measurementfor permeance is gr/h·ft2·in.Hg, which is commonly
referred to as “perm” units.
pH: a measure of the
acidity or alkalinity of a solution, with neutrality represented by a
value of 7, with increasing acidity represented by increasingly smaller
values, and with increasing alkalinity represented by increasingly larger
Phased applicaton: the installation of a
roofing or waterproofing system during two or more separate time intervals
or different days. Application of surfacings at different time intervals
are typically not considered phased application. (see Surfacing.) A
roofing system not installed in a continuous operation.
framing: a square or rectangular pattern of ridges in a roof
membrane or covering over insulation or deck
Pigment: an insoluble compounding material
used to impart color.
Pinhole: a tiny hole in a
coating, film, foil, membrane or laminate comparable in size to one made
by a pin.
Pipe boot: prefabricated flashing piece used
to flash around circular pipe penetrations.
Pitch-pocket (Pitch-pan): a flanged, open
bottomed enclosure made of sheet metal or other material, placed around a
penetration through the roof, filled with grout and bituminous or
polymeric sealants to seal the area around the
Pittsburgh lock seam: a method of
interlocking metal, usually at a slope change.
cement: a roofing industry generic term used to describe asphalt
roof cement that is a trowelable mixture of solvent-based bitumen, mineral
stabilizers, and other fibers and/or fillers. Generally, intended for use
on relatively low slopes, not vertical surfaces. (also see Asphalt roof
cement and Flashing cement.)
Plasticizer: a material
incorporated in a material to increase its ease of workability,
flexibility or distensibility.
in some thermoplastic roofing membranes, the loss of plasticizer chemicals
from the membrane, resulting in shrinkage and embrittlement of the
membrane, typically PVC.
Pliability: the material
property of being flexible or moldable.
Ply: a layer
of felt or ply sheet in a built-up roof membrane or roof
PMR: protected membrane
Polyester: a polymer in which the repeated
structural unit in the chain is of the ester
Polyisobutylene (PIB): a product formed by the
polymerization of isobutylene. May be compounded for use as a roof
Polymer: a macromolecular material
formed by the chemical combination of monomers having either the same or
different chemical composition.
bitumen: see Modified bitumen.
diphenyl diisocyanate (PMDI): component A in SPF. An organic
chemical compound having two reactive isocyanate groups. It is mixed with
the B component to form polyurethane.
a chemical reaction in which monomers are linked together to form
Polypropylene: a polymer prepared by the
polymerizaton of propylene as the sole
Polyol: a polyhydric alcohol, i.e., one
containing three or more hydroxyl groups, one component of
polyisocyanurate and polyurethane compounds.
(PVC): a synthetic thermoplastic polymer prepared from
vinylchloride. PVC can be compounded into flexible and rigid forms through
the use of plasticizers, stabilizers, fillers and other modifiers. Rigid
forms are used in pipes; flexible forms are used in the manufacture of
sheeting and roof membrane materials.
polymer prepared by the polymerization of styrene as the sole
Pond: a surface which is incompletely
Ponding: the excessive accumulation of wter
at low-lying areas on a roof that remains after the 48 hours after the end
rainfall under conditions conducive to drying.
rivet: a relatively small-headed pin with an expandable head for
joining light gauge sheet metal.
texture: in SPF roofing, the condition in which the foam surface
shows a coarse texture where valleys form sharp angles. This surface is
unacceptable for proper coating and protection.
drainage: the drainage condition in which consideration has been
made during design for all loading deflections of the deck and additional
roof slope has been provided to ensure drainage of the roof area within 48
hours following rainfall during conditions conducive to
Positive side waterproofing: an application
where the waterproofing systems and the source of the hydrostatic pressure
are on the same side of the structural element.
(Working life): the period of time during which a reacting
compostition remains suitable for its intended processing after mixing
with reaction initiating agents.
Pourable sealer: a
type of sealant often supplied in two parts and used at difficult-to-flash
penetrations, typically in conjunction with pitch-pockets to form a
Press brake: a machine used in cold-forming
sheet metal or strips of metal into desired
Prestressed concrete: concrete in which the
reinforcing cables, wires or rods in the concrete are tensioned before
there is load on the structural member, holding the concrete in
compression for greater strength.
a metal with solder or tin alloy prior to soldering or brazing
Primer: (1) a thin, liquid-applied solvent-based
bitumen that may be applied to a surface to improve the adhesion of
subsequent applications of bitumen; (2) a material that is sometimes used
in the process of seaming single-ply membranes to prepare the surfaces and
increase the strength (in shear and peel) of the field splice; (3) a thin
liquid applied material that may be applied to the surface of SPVF to
improve the adhesion of subsequent application of SPVF protective
Proportioner: the basic pumping unit for SPF
or two-component coating systems. Consists of two positive displacement
pumps designed to dispense two components at a preicsely controlled
Protection course: a sacrificial material used
to shield a waterproofing material from damaging external
Protection mat: a sacrificial material used to
shield one roof system component from another.
membrane roof (PMR): an insulated and ballasted roofing assembly
in which the insulation and ballast are applied on top of the membrane
(sometimes referred to as an “inverted roof
Psychrometer: an instruments used to
measur humidity in the atmosphere from two thermometers which are similar
except that the bulb of the other being dry.
chart: chart showing the relationship between dew point
temperature, dry bulb temperature, wet bulb temperature and relative
Puncture resistance: the ability of a
material to withstand the action of a penetrating or puncturing
Purlin: horizontal secondary structural member
that transfers loads from the primary structural
PVC: polyvinyl chloride.
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R-value: see Thermal
Racking: a method of asphalt shingle
application, also referred to as the straight-up method, whereby shingle
courses are applied vertically, up the roof rather than laterally or
across and up.
Rafter: one of a series of sloped
structural members, that extend from the ridge or hip to the downslope
perimeter or eave, designed to support the roof deck and its associaated
Raggle: a groove or slot, often cut in a
masonry wall or other vertical surface adjoining a roof, for inserting an
inset flashing component such as a reglet.
sloped edge of a roof at or adjacent to the first or last
Rake-starter (Bleeder strip): starter-strip
used along rake edges in conjunction with asphalt shingle
Re-cover: the additon of a new roof membrane
or steep-slope roof covering over a major portion of an existing roof
assembly. This process does not involve removal of the existing
Reflectivity: see Light
Reglet: a sheet metal receiver for the
attachment of counterflashing. A reglet may be surface-mounted, inset into
a raggle or embedded behind cladding.
membrane: a roofing or waterproofing membrane that has been
strengthened by the additon or incorporation of one or more reinforcing
materials, including woven or nonwoven glass fibers, polyester mats or
scrims, nylon, or polyethylene sheeting.
(RH): the ratio of the pressure of water vapor present in a given
volume of air to the pressure of fully saturated water vapor at the same
temperature, expressed as a percentage.
Release tape (or
Strip): a plastic film or paper strip that is applied to the back
of self-sealing shingles and other materials. The strip prevents the
material from sticking together in the roll or bundle. With asphalt
shingles, the strip need not be removed for application of the
Replacement: the practice of removing an
existing roof system down to the roof deck and replacing it with a new
Reroofing: the process of re-covering,
or tearing-off and replacing an existing roof
Resin: component B in SPF. This component
contains a catalyst, blowing agent, fire retardants, surfactants and
polyol. It is mixed with the A component to form
Ridge: highest point on the roof,
represented by a horizontal line where two roof areas intersect, running
the length of the area.
Ridge cap: a material or
covering applied over the ridge of a roof.
course: the last or top course of roofing materials, such as
tile, roll roofing, shingles, etc,. that covers the ridge and overlaps the
intersecting field roofing.
Ridge vent: a ventilator
located at the ridge that allows the escape of warm and/or moist air from
the attic area or rafter cavity.
Roll materials: a general term applied to
rolls of roofing felt, ply sheet, etc., which are typically furnished in
Roll roofing: coated felts, either smooth or
Roof: (1) the cover of a building; 92)
to cover with a roof.
Roof area divider: refer to area
Roof area expansion Joint: see expansion
Roof assembly: an assembly of interacting roof
components including the roof deck, vapor retarder (if present),
insulation and roof covering.
Roof cement: see Asphalt
roof cement or Coal tar roof cement.
the exterior roof cover or skin of the roof assembly, consisting of
membrane, panels, sheets, shingles, tiles, etc.
curb: raised frame used to mount mechanical units (such as air
conditioning or exhaust fans), skylights, etc. on a roof.
jack: a metal or wood bracket used to support toe-boards on
steep-slope roofs. (also see Flashing Collar.)
overhang: a roof extension beyond the exterior wall of a
Roof seamer: (1) machine that crimps
neighboring metal roof panels together; (2) machine that welds laps of
membrane sheets together using heat, solent, or dielectric
Roof slope: the angle a roof surface makes
with the horizontal, expressed as a ratio of the units of vertical rise to
the units of horizontal length (sometimes referred to as run). For English
units of measurement, when dimensions are given in inches, slope may be
expressed as a rato of rise to run, such as 4:12 or as an
Roof system: a system of interacting roof
components, generally consisting of a membrane or primary roof covering
and roof insulation (not including the roof deck) designed to weatherproof
and, sometimes, to improve the building's thermal
Rosin paper (specifically Rosin-sized sheathing
paper): a nonasphaltic paper used as a sheathing paper or slip
sheet n some roof systems.
Rubber: a material that is
capable of recovering from large deformations quickly and
Run: horizontal dimension of a slope.
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Saddle: a small tapered/sloped roof area
structure that helps to channel surface water to drains. Frequently
located in valley. A saddle is often constructed like a small hip roof or
pyramid with a diamond-shaped base. (see
Sag: undesirable excessive flow in material
after application to a surface.
Saturated felt: a felt
that has been immersed in hot bitumen; the felt adsorbs as much bitumen as
it can retain under the processing conditions, but remains porous and
SBCCI: Southern Building Code Congress
SBS: see Styrene butadiene
Scarfed: shaped by
Screeding: the process of striking off
excess concrete to bring the top surface of the concrete to the proper
finish and elevation.
Screen wall: a nonstructual wall
erected around units or curbs on a roof. Typically the framing consists of
girts with a wood or metal covering attached to the
Scrim: a woven, nonwoven or knitted fabric
composed of continuous strands of material used for reinforcing or
Scupper: drainage device in
the form of an outlet through a wall, parapet wall or raised roof edge
lined with a soldered sheet metal sleeve.
hatch that provides access to the roof from the interior of the
SDI: Steel Deck
Sealant: (1) a material that has the
adhesive and cohesive properties to form a seal; (2) a mixture of
polymers, fillers, and pigments used to fill and seal joints where
moderate movements is expected; unlike caulking, it cures to a resilient
Sealant backing: a compressible material placed
in a joint before applying a sealant.
coating designed to prevent excessive absorption of finish coats into
porous surfaces; a coating designed to prevent
Sealing washer: a rubber or neoprene washer,
sometimes metal-backed, typically placed on a fastener to prevent water
from migrating into and through the fastener
Seam: a joint formed by mating two separate
sections of material. Seams can be made or sealed in a variety of ways,
including adhesive bonding, hot-air welding, solvent welding, using
adhesive tape, sealant, etc.
Seam sample: in
single-ply and sometimes modified bitumen membrane roofing, a sample from
the membrane that extends through the side lap of adjacent rolls of
membrane, taken for the purpose of assessing the quality of the
Self-adhering membrane: a membrane that can
adhere to a substrate and to itself at overlaps without the use of an
additional adhesive. The undersurface of a self-adhering membrane is
protected by a release paper or film, which prevents the membrane from
bonding to itself during shipping and handling.
screw: a fastener that taps and drills its own hole during
Self-sealing shingle: an asphalt shingle
containing a factory-applied strip or spots of heat sensitive adhesive
intended to adhere the overlying shingle once installed on the roof and
warmed by the sun.
Self-tapping screw: a fastener that
forms receiving threads when turned in a previously drilled
Selvage: (1) an edge or edging that differs from
the main part of a fabric, granule-surfaced roll roofing or cap sheet, or
other material;(2)a specially defined edge of the material (lined for
demarcation), which is designed for some special purpose, such as
overlapping or seaming.
Separator layer: refer to Slip
Service temperature limits: the minimum or
maximum temperature at which a coating, SPF or other material will perform
Set: to convert into a fixed or
hardened state by chemical or physical
Shading: slight differences in surfacing
color, such as shingle granule coloring, that may occur as a result of
Shark fin: an upward-curled
felt side lap or end lap.
Shear strength: the
resistance to forces that cause two contiguous parts of a body to slide
relative to each other in a direction parallel to their
Shed roofs: a roof having only one sloping
plane and no hips, ridges or valleys.
Shelf life: the
maximum time a packaged material can be stored under specified conditions
and still meet the performance requirements
Shingle: (1) a small unit of prepared
roofing designed for installation with similar units in overlapping rows
or courses on inclines normally exceeding 3:12 slope (14°); (2) to cover
with shingles; (3)to apply any sheet material in succeeding overlapping
rows like shingles.
Shingling: (1) the applicaton of
shingles; (2) the procedure laying parallel felts so that one longitudinal
edge of each felt overlaps and the other longitudinal edge underlaps an
adjacent felt. Normally felts are shingled on a slope so that water flows
over rather than against each lap.
decrease in one or more dimensions of an object or
Shrinkage crack: in waterproofing, a
separation in a material, such as a concrete substrate, caused by the
inability of the material to resist a reduction in size which occurs
during its hardening or curing process or both.
abbreviation for the International System of Units (Le Systeme
Side lap: the continuous
longitudinal overlap of neighboring like materials.
fastener: a fastener used to connect adjacent panels together at
the side lap. Siding: the finish covering of an
exterior wall of a frame building; the siding may be a cladding material
such as wood, aluminum or vinyl (but not
Sieve: an apparatus with square apertures
for separating sizes of material.
Sill: the bottom
horizontal framing member of an opening, such as below a window or
Sill flashing: a flashing of the bottom
horizontal framing member of an opening, such as below a window or
Single-lock standing seam: a standing seam that
uses one overlapping interlock between two seam panels, in contrast with
the double interlocking used in a double standing
Single-ply membranes:roofing membranes that are
field applied using just one layer of membrane material (either
homogeneous or composite) rather than multiple
Single-ply roofing: a roofing system in which
the principal roof covering is a single layer flexible membrane often
thermoset or thermoplastic membrane.
formation of a dese film on the surface of a liquid coating or
Skirt flashing: a formed metal counterflashing
secured under a mechanical unit or skylight to cover and protect the upper
edge of a base flashing and its associated
Skylight: an opening in a roof that is
glazed with a transparent or translucent material; used to admit diffused
light to the space below.
Slab on grade: a horizontal
placement of concrete placed directly over a prepared earth
Slag: a hard aggregate that is left as a
residue from blast furnaces, which may be used as a surfacing material on
certain (typically bituminous) roof membrane
Slate: a hard, brittle metamorphic rock
consisting mainly of clay minerals, used extensively as dimensional stone
for steep roofing and in granular form as surfacing on some other roofing
Slating hook: a steep-slope roofing
attachment device, shaped like a hook, that can be used for fastening
Slip sheet: sheet material, such as
reinforced kraft paper, rosin-sized paper, polyester scrim or polyethylene
sheeting, placed between two components of a roof assembly (such as
between membrane and insulation or deck) to ensure that no adhesion occurs
between them and to prevent possible damage from chemical incompatibility,
wearing or abrasion of the membrane.
Slit sample: in
SPF roofing, a small cut about 1 inch x 1/2 inch x 1/2 inch (25 mm x 13 mm
x 13 mm), in a half-moon shape, used to measure coating film
Slope: the angle of incline, usually
expressed as a ratio of rise to run, or as an angle. (See Roof
SMACNA: Sheet Metal and Air Conditioning
Contractors National Association.
texture: in SPF roofing, the condition of the foam in which the
surface shows spray undulation and is ideal for receiving a protective
Smooth-surfaced roof: a roof membrane without
mineral granule or aggregate surfacing.
Snap-on cap: a
separate cap that snaps on over the vertical legs of some single standing
or batten seam metal roof systems.
Snow guard: a
series of devices attached to the roof in a pattern that attempts to hold
snow in place, thus preventing sudden snow or ice slides from the roof;
any device intended to prevent snow from sliding off a
Snow load: the live load due to the weight of
snow on a roof; included in design
Soffit: the exposed undersurface of any
exterior overhanging section of a roof eave.
a premanufactured or custom built air inlet source located at the
downslope eave or in the soffit of a roof assembly.
point: the temperature at which bitumen becomes soft enough to
flow, as determined by an arbitrary, closely defined method (ASTM Standard
test method D 36 or D 3461).
Softening point drift: a
change in the softening point of bitumen during storage or application.
Soil stack: a sanitation pipe that
penetrates the roof; used to vent plumbing
Solder: a lead/tin mixture that is melted
and used to bond two pieces of some types of metals
Solid mopping: see
Solids content: the percentage by weight of
the nonvolatile matter in an adhesive.
liquid used to dissolve another material.
cleaners: used to clean some single-ply roofing membranes prior
to splicing, typically including heptane, hexane, white gasoline, and
Solvent welding: a process where a
liquid solvent is used to chemically weld or join together two or more
layers of certain membrane materials (usually
Spalling: breaking off of plate-like
pieces from a concrete, rock or masonry surface.
asphalt: asphalt complying with ASTM D 312, Type IV. (see
Specification: a precise statement of a set
of requirements to be satisfied by a material, product, system, or
SPF: spray polyurethane
SPFA: Sprayed Polyurethane Foam Alliance (a
business unit of the American Plastics Council).
compound: a term used to describe the raw materials (isocyanate
and resin) used to make polyurethane foam.
block: a small masonry or polymeric block laid on the ground or
lower roof below the opening of a downspout used to help prevent soil
erosion and aggregate scour in front of the
Splice: bonding or joining of overlapping
materials. (see Seam.)
Splice plate: a metal plate
placed underneath the joint between two pieces of
Splice-tape: cured or uncured synthetic rubber
tape used for splicing membrane materials.
membrane tear resulting from tensile stresses.
slab: a term used to describe two separate concrete slabs. The
first is placed as a slab on grade or suspended
slab, and covered with
waterproofing and a drainage system. The second slab, also referred to as
a topping slab, is then placed over the underlying slab and
Spot mopping: see
Sprayed polyurethane foam (SPF): a foamed
plastic material, formed by spraying two components, PMDI (A component)
and a resin (B component) to form a rigid, fully adhered, water-resistant,
and insulating membrane.
Spread coating: a
manufacturing process in which membranes are formed using a liquid
compound that is spread onto a supporting reinforcement base layer and
then dried to its finished condition.
mopping: see Mopping.
Spunlaced: a nonwoven
fabric made by mechanically bonding a dry-laid staple fabric by water jet,
which entangles the individual fibers.
Spud: to remove
the roofing aggregate and most of the bituminous top coating by scraping
Square: a unit used in measuring roof
area equivalent to 100 square feet (9.29 m2) of roof
Square-tab shingles: shingles with tabs that are
all the same size and exposure.
Squeegee: (1) a blade
of leather or rubber set on a handle and used for spreading, pushing or
wiping liquid material on, across or off a surface; (2) to smooth, wipe or
treat with a squegee.
Stainless steel: an alloy of
steel that contains chromium and also may contain nickel or copper.
Generally, has very good resistance to corrosion.
seam: in metal roofing, a type of seam between adjacent sheets of
material made by turning up the edges of two adjacent metal panels and
then folding or interlocking them in a variety of ways.
course: the first layer of roofing, applied along a line adjacent
to the downslope perimeter of the roof area. With steep-slope
watershedding roof coverings, the starter course is covered by the first
Starter sheets: (1) felt, ply sheet or
membrane strips that are made or cut to widths narrower than the standard
width of the roll and used to start the shingling pattern at an edge of
the roof; (2) particular width sheets designed
for perimeters in some
mechanically attached and fully adhered single-ply
Starter strip: roll roofing or shingle strips
applied along the downslope eave line before the first course of roofing
and intended to fill spaces between cutouts and joints of the first
Static load: any load, as on a structure, that
does not change in magnitude or position with time.
a malleable alloy of iron and carbon produced by melting and
refining pig iron and/or scrap steel; graded according to the carbon
content (in a range from 0.02 to 1.7%); other elements, such as manganese
and silicon, may be included to provide special
Steel joist (open web steel joist):
normally used as a horizontal supporting member between beams or other
structural members, suitable for the support of some roof
Steep asphalt: asphalt complying with ASTM D
312, Type III. (see Asphalt.)
Steep-slope roofs: a
category of roofing that generally include water-shedding types of roof
coverings installed on slopes exceeding 3:12 (14 degrees).
flashing: individual pieces of sheet metal material used to flash
walls, around chimneys, dormers and such projections along the slope of a
roof. Individual pieces are overlapped and stepped up the vertical
Stick clip: in waterproofing, a
non-penetrating fastener that is adhered to the waterproofing surface;
typically used to retain insulation, drainage panels, prefabricated
protection materials, etc., against the waterproofing to prevent sliding
Stiffener rib: small intermediate
bends in a metal pan used to strengthen the panel.
anchor: see Wind clip.
Strapping (felts): a
method of installing roofing rolls or sheet good materials parallel with
the slope of the roof.
Straw nail: a long-shanked
nail. Sometimes used for fastening over tile at hips and
Stress: the internal resistance of a material
to a force, measured as a force per unit
Striations: a parallel series of small grooves,
channels, or impressions typically within a metal roof panel used to help
reduce the potential for oil-canning.
Strip shingles: asphalt shingles that are
manufactured in strips, approximately three times as long as they are
Strippable films: (for metal) added protection
of plastic films sometimes applied to coated or finished metals after the
coil coating process. Applied after prime and top coats to resist damage
to the finish prior to and during shipping, fabrication and
Stripping or strip-flashing: membrane
flashing strips used for sealing or flashing metal flashing flanges into
the roof membrane.
Stripping in: application of
membrane stripping ply or plies.
Structural panel: a metal roof panel
designed to be applied over open framing rather than a continuous or
closely spaced roof deck.
Styrene butadiene rubber:
high molecular weight polymers having rubber-like properties, formed by
the random copolymerization of styrene and butadiene
Styrene butadiene styrene copolymer (SBS):
high molecular weight polymers that have both thermoset and thermoplastic
properties, formed by the block copolymerization of styrene and butadiene
monomers. These polymers are used as the modifying compound in SBS polymer
modified asphalt roofing membranes to impart rubber-like qualities to the
Substrate: the surface upon which the roofing
or waterproofing membrane is applied (e.g., in roofing, the structural
deck or insulation).
Sump: an intentional depression
around a roof drain or scupper that promotes drainage.
pan: a metal pan used to create a depression around a drain or
scupper to enhance drainage.
Superimposed loads: loads
that are added to existing loads. For example, a large stack of insulation
boards placed on top of a structural steel deck.
erosion: the wearing away of a surface due to abrasion,
dissolution or weathering.
Surface texture: the
resulting surface from the final pass of SPF. The following terms are used
to describe the different
SPF surface textures: smooth
orange peel, coarse orange peel, verge of popcorn, popcorn, treebark, and
Surfacing: the top layer or layers of a
roof covering, specified or designed to protect the underlying roofing
from direct exposure to the weather.
contraction for “surface active agent;” a material that improves the
emulsifying, dispersing, spreading, wetting or other surface-modifying
properties of liquids.
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Tab: the exposed portion of strip shingles
defined by cutouts.
Tack-free time: in SPF-based
roofing, a curing phase of polyurethane foam to when the material is no
longer sticky. When the polyurethane foam is tack free, it can be sprayed
over with another pass, referred to as a “lift”.
With some care the
polyurethane foam can be walked on soon after it is tack
Talc: whitish powder applied at the factory to
the surface of some roofing materials (e.g., vulcanized EPDM membranes),
used as a release agent to prevent adhesion of the membrane to
Tapered edge strip: a tapered insulation strip
used to (1) elevate and slope the roof at the perimeter and at curbs, and
(2) provide a gradual transition from one layer of insulation to
Taping: (1) the technique of connecting
joints between insulation boards or deck panels with tape; (2) the
technique of using self-adhering tape-like materials to seam or splice
Tar: a brown or black bituminous
material, liquid or semi-solid in consistency, in which the predominating
constituents are bitumens obtained as condensates in the processing of
coal, petroleum, oil-shale, wood, or other organic
Tar boils: bubbles of moisture vapor
encased in a thin film of bitumen, also known as
Tarred felt: see Coal tar
Tear-off and reroof: the removal of all roof
system components down to the structural deck, followed by installation of
a completely new roof system.
Tear resistance: the
load required to tear a material, when the stress is concentrated on a
small area of the material by the introduction of a prescribed flaw or
notch. Expressed in psi (pounds force) per inch width or kN/m (kilonewton
per meter width).
Tear strength: the maximum force
required to tear a specimen.
Tensile strength: the
strength of a material under tension as distinct from torsion, compression
Tension leveling: the process of pulling
metal coil stock between two spools under a certain pressure to help
reduce side camber and potential oil canning in the coil stock caused by
manufacturing and cutting processes.
treatment or method of anchoring and/or sealing the free edges of the
membrane in a roofing or waterproofing system.
an alloy of lead and tin, used to coat sheets of carbon steel or stainless
steel for use as metal roofing sheet.
low-fired clay, either glazed or unglazed.
Test cut: a
sample of the roof system or assembly which exposes the roof deck and is
used to diagnose the condition of the membrane, evaluate the type and
number of plies or number of membranes, or rates of application (e.g., the
weight of the average interply bitumen moppings).
block: a compression-resistant insulation block installed between
structural steel roof panels and their supporting members to help maintain
insulation R-values and reduce condensation.
bridge: the penetration of a material of high thermal
conductivity (e.g., a metal insulation or roof membrane fastener) through
a material of low thermal conductivity (e.g., thermal insulation); the
result is a lowered thermal resistance for the assembly.
Thermal cycling: sequence of values caused by a
repetitive temperature differential due to changes in radiant
Thermal conductance (C): the time rate of heat
flow through a unit area of a body induced by a unit temperature
difference between bodies. In English (inch-pound) units of measurement,
the number of BTUs that pass through a specified thickness of a one square
foot (0.09 m2) sample of material in one hour with a temperature
difference between the two surfaces of 1° F. In English (inch-pound) units
it is expressed as Btu/h•ft2•F. Note 1: A thermal conductance (C) value
applies to a specific thickness of a specific material. Note 2: It is
mathematically incorrect to multiply or divide the thermal conductance (C)
value for a specific thickness of a material to determine the thermal
conductance value of a different thickness of the same material. Note 3:
It is mathematically incorrect to add thermal conductance (C) values to
determine overall thermal performance. If it is necessary to determine the
overall thermal performance of a construction, it is appropriate to
convert the individual thermal conductance (C) values to thermal
resistance (R) values (i.e., R= 1/c), and then add the thermal resistance
values (i.e., RT=R1, + R2 + ...).
(k): the time rate of heat flow through a unit area of a
homogeneous material in a direction
perpendicular to isothermal planes
induced by a unit temperature gradient is called thermal conductivity (k
or kvalue). In English (inch-pound) units of measurement, it is the number
of BTUs that pass through a 1 inch (25 mm)
thickness of a 1 square foot
(0.09 m2) sample of material in one hour with a temperature difference
between the two surfaces of 1°F. In English (inch-pound) units it is
expressed as Btu•inch/h•ft2•°F. Note 1: A thermal conductivity (k) value
applies to 1 inch (25 mm) thickness of a specific material. Note 2: It is
mathematically incorrect to add, multiply, or divide the thermal
conductivity (k) value of a material to determine the thermal performance
value of a different thickness of the same material. If it is necessary to
determine the thermal performance of a specific thickness of a material,
it is appropriate to convert the thermal conductivity (k) of the material
to a thermal resistance (R) value (i.e., R = 1/k), and then perform the
Thermal expansion: the
increase in the dimension or volume of a body due to temperature
Thermal insulation: a material applied to
reduce the flow of heat.
Thermal movement: changes in dimension of a
material as a result of temperature changes.
(R): under steady conditions, thermal resistance is the mean
temperature difference between two defined surfaces of material or
construction that induces unit heat flow through a unit area. In
(inch•pound) units it is expressed as °F•ft2•h/Btu. Note 1: A
thermal resistance (R) value applies to a specific thickness of a material
or construction. Note 2: The thermal resistance (R) of a material is the
reciprocal of the thermal conductance (C) of the same material (i.e., R =
1/C). Note 3: Thermal resistance (R) values can be added, subtracted,
multiplied, and divided by mathematically appropriate
Thermal shock: the stress-producing
phenomenon resulting from sudden temperature changes in a roof membrane
when, for example, a cold rain shower follows brilliant
Thermal stress: stress introduced by uniform
or non-uniform temperature change in a structure or material that is
contained against expansion or contraction.
transmittance (U or U-factor): thermal transmittance (U or
U-factor) is the time rate of heat flow per unit area under steady
conditions from the fluid (e.g., air) on the warm side of a barrier to the
fluid (e.g., air) on the cold side, per unit temperature difference
between the fluids. In English (inch•pound) units expressed as
Btu/h•ft2•°F. Note 1: A thermal transmittance (U) value applies to the
overall thermal performance of a system (e.g., roof assembly). Note 2:
Thermal transmittance (U) is sometimes called the overall coefficient of
heat transfer. Note 3: Thermal transmittance (U) is reciprocal of the
overall thermal resistance (RT) of a system (i.e., U =
Thermography, Infrared: see Infrared
Thermoplastic: a material that softens
when heated and hardens when cooled. This process can be repeated provided
that the material is not heated above the point at which decomposition
Thermoplastic olefin membrane (TPO): a blend
of polypropylene and ethylene-propylene polymers. Colorant, flame
retardants, UV absorbers, and other proprietary substances which may be
blended with the TPO to achieve the desired physical properties. The
membrane may or may not be reinforced.
class of polymers that, when cured using heat, chemical, or other means,
changes into a substantially infusible and insoluble
Thinner: (1) a volatile liquid added to an
adhesive or coating material to modify the consistency or other
properties; (2) a liquid used to clean equipment or other
Thixotropic: the property of a material that
enables it to stiffen in a relatively short time on standing, but upon
agitation or manipulation to change to a very soft consistency or to a
fluid of high viscosity, the process being completely
Through-wall flashing: a water-resistant
membrane or material assembly extending totally through a wall and its
cavities, positioned to direct water within the wall to the exterior,
usually through weep holes.
Tie-in: in roofing and
waterproofing, the transitional seal used to terminate a roofing or
waterproofing application at
the top or bottom of flashings or by
forming a watertight seal with the substrate, membrane, or adjacent
roofing or waterproofing system.
condition created by the overlapping intersection of three or four sheets
in the membrane.
Toggle bolt: a bolt having a nut with
pivoted, flanged wings that close against a spring when it is pushed
through a hole, and open after emerging from the hole; used to fasten
objects to a hollow wall or to a wall which is accessible only from one
Tongue and groove planks: one of the oldest
types of dimensional structural wood used as roof decking. The sides are
cut with convex and concave grooves so adjacent planks may join in
alignment with each other to form a uniform roof
Torch-applied: method used in the installation
of polymer modified bitumen membranes characterized by using open flame
propane torch equipment.
Traffic bearing: in waterproofing, a membrane
formulated to withstand a predetermined amount of pedestrian or vehicular
traffic with separate protection and a wear course.
seam: the joint between the top of one metal roof panel and the
bottom of the next panel, which runs perpendicular to the roof
Treebark surface texture: in SPF roofing, the
surface condition of the foam which shows a coarse texture where valleys
form sharp angles. This surface is unacceptable for proper coating and
Tuckpointing: the process of removing
deteriorated mortar from an existing masonry joint and troweling new
mortar or other filler into the joint.
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U-Value: see Thermal
UBC: Uniform Building
UL: Underwriters Laboratories,
UL label: an identification label or seal affixed
to a roofing product or package with the authorization of Underwriters
Laboratories, Inc. The presence of the label indicates that the product
has met certain performance criteria.
(UV): invisible light radiation, adjacent to the violet end of
the visible spectrum, with wavelengths from about 200 to 400 nm
Underlayment: an asphalt-saturated felt
or other sheet material (may be self-adhering) installed between the roof
deck and roof covering, usually used in a steep-slope roof construction.
Underlayment is primarily used to separate the roof covering from the roof
deck, shed water and provide secondary weather protection for the roof
area of the building.
Underwriters Laboratories, Inc. (UL):
an organization that tests, rates and classifies roof assemblies
for their resistance to fire, impact, leakage, corrosion of metal
components and wind uplift.
Uplift: see Wind uplift.
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Valley: the internal angle formed by the
intersection of two sloping roof planes.
migration: the movement of water vapor from a region of high
vapor pressure to a region of lower vapor pressure.
pressure: the pressure exerted by a vapor of a solid or liquid
when in equilibrium with the liquid or solid.
a layer(s) of material or a laminate used to appreciably reduce
the flow of water vapor into a roof assembly.
(1) a single wythe of masonry for facing purposes that may not be
structurally connected; (2) any of the thin layers of wood glued together
to form plywood.
Vent: an opening designed to convey
air, heat, water vapor or gas from inside a building or a building
component to the atmosphere.
Ventilator: an accessory
that is designed to allow for the passage of air.
popcorn texture: in SPF roofing, the verge of popcorn surface
texture is the roughest texture suitable for receiving the protective
coating on a sprayed polyurethane foam roof. The surface shows a texture
where nodules are larger than valleys, with the valleys relatively cured.
This surface is acceptable for receiving a protective coating only because
of the relatively cured valleys. However, the surface is considered
undesirable because of the additional amount of coating material required
to protect the surface properly.
aggregate used in lightweight insulating concrete, formed by heating and
expanding of a micaceous material.
resistance of a material to flow under stress. For bitumen, measured in
centipoise. (see Viscous.)
Viscous: resistant to flow
Void: an open space or break in
Volatile: a relative term expressing the
tendency to form vapor.
Volatile organic compounds
(VOC): means any compound of carbon, excluding carbon monoxide,
carbon dioxide, carbonic acid, metallic carbides or carbonates, and
ammonium carbonate, which participate in atmospheric
Vulcanization: an irreversible process
during which a rubber compound, through a change in its chemical structure
(for example, cross-linking), becomes less plastic and more resistant to
swelling by organic liquids and elastic properties are conferred,
improved, or extended over a greater range of temperature.
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WSRCA:Western States Roofing Contractors
Warm roof assembly: a roof assembly
configured with each component placed immediately on top of the preceding
component; each component is in contact with the adjacent component. No
space is provided for ventilation of the roof assembly. Also known as a
“compact” roof assembly.
Wash coat: a primer,
typically provided on the back side of painted metal products to help
protect the underlying metal from wear and corrosion.
cure: a method of curing a material, such as concrete, by
applying a fine mist of water over the surface to control the rate of
moisture evaporation from the material.
Water-shedding: the ability of individual,
overlapping components to resist the passage of water without hydrostatic
Water stop: a diaphragm used across a joint
as a sealant, usually to prevent the passage of water.
table: the level within the ground, below which the soil is
saturated with water.
Water vapor transmission: a
measure of the rate of transmission of water vapor through a material
under controlled laboratory conditions of temperature and humidity.
Customary units are grains/h•ft2.
quality of a membrane, membrane material, or other component to prevent
Waterproofing: treatment of a surface or
structure to prevent the passage of water under hydrostatic
Wear course: the top layer of surfacing that
carries pedestrian or vehicular traffic. Sometimes referred to as wearing
Wearing surface: see Wear
Weatherproof: the ability of a membrane or
roof covering to prevent the passage of water with a limited amount of
Weep holes: small openings whose
purpose is to permit drainage of water that accumulates inside a building
component (e.g., a brick wall, skylight frame, etc.).
to join pieces of metal together by heat
Wet: a condition where free water is present
in a substance.
Wet bulb temperature: the temperature
of air as registered by a thermometer whose bulb is covered by a water
Wet film thickness: the thickness,
expressed in mils, of a coating or mastic as applied but not cured. For
comparison, see Dry film thickness.
process of moisture movement by capillary action.
clip: a steep-slope roofing attachment device that fits over the
butt end of tile, slate and stone to help secure individual roofing units
from wind uplift.
Wind load: force exerted by the wind
on a structure or part of a structure.
the force caused by the deflection of wind at roof edges, roof peaks or
obstructions, causing a drop in air pressure immediately above the roof
Wire tie system: a system of attachment for
steep-slope roofing units (e.g., tile, slate and stone) using fasteners
(nails and/or screws) in conjunction with wire to provide a concealed
Work slab: see Mud
Woven valley: a method of valley construction in
which shingles or roofing from both sides of the valley extend across the
valley and are woven together by overlapping alternate courses as they are
Wythe: a masonry wall, one masonry unit, a
minimum of two inches thick.
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Yield: in SPF-based roofing, the volume of
foam per unit weight, normally expressed as board feet per pound or board
feet per 1000 pounds.
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Z section: a member formed in the shape of
a “Z” from coiled steel stock.
Zinc: a hard bluish
white metal, brittle at normal temperatures, very malleable and ductile
when heated; not subject to corrosion; used for galvanizing sheet steel
and iron, in various metal alloys, and as an oxide for white paint