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A
Aggregate:
(1) crushed stone, crushed slag or water-worn gravel used for surfacing
a built-up roof. (2) any granular mineral material.
Alligatoring: the
cracking of the surfacing bitumen on a built-up roof, producing a
pattern of cracks similar to an alligator's hide; the cracks may or may
not extend through the surfacing bitumen.
Ambient Temperature:
temperature of air - - air temperature.
Application Rate:
the quantity (mass, volume or thickness) of material applied per unit
area.
Area Divider: a
raised, double wood member attached to a properly flashed wood base
plate that is anchored to the roof deck. It is used to relieve thermal
stresses in a roof system where no expansion joints have been provided.
Asbestos: a group of
natural, fibrous, impure silicate materials.
Asphalt: A dark brown to black material in which
the predominating constituents are bitumens, which occur in nature or
are obtained in petroleum processing.
Asphalt, Air Blown: an asphalt produced by
blowing steam through molten asphalt to modify its properties, normally
used for highway bitumen.
Atactic Polypropylene: a group of high molecular
weight polymers formed by the polymerization of propylene
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B
Backnailing: the practice of blind nailing (in addition to hot
mopping) all the plies of a substrate to prevent slippage. (See BLIND
NAILING.)
Ballast: an anchoring material, such as
aggregate, precast pavers, which employ the force of gravity to hold (or
assist in holding) membranes in place.
Base Flashing: see FLASHING.
Base
Ply: the base ply is the first ply when it is a separate ply
and not part of a shingled system.
Base Sheet: a saturated or coated felt placed as
the first ply in some multi-ply built up roof membranes.
Bentonite: a clay formed from decomposed
volcanic ash, with a high content of the mineral montmorillonite; has
the capacity of absorbing a considerable amount of water, and swells
accordingly.
Bitumen: the generic term for an amorphous,
semi-solid mixture of complex hydrocarbons derived from any organic
source. Asphalt and coal tar are the two used in the roofing industry.
Bituminous: containing or treated with bitumen.
Examples: bituminous concrete, bituminous concretes, bituminous felts
and fabrics, bituminous pavement.
Bituminous Grout: a mixture of bituminous
material and fine sand that will flow into place without mechanical
manipulation when heated.
Blind Nailing: the practice of nailing the back
portion of a roofing ply.
Blister: a spongy raised portion of a roof
membrane, ranging in area from 1 inch in diameter and of barely
detectable height upward. Blisters result from the pressure buildup of
gases entrapped in the membrane system. these gases most commonly are
air and/or water vapor. Blisters usually involve delamination of the
underlying membrane plies.
Bond: the adhesive and cohesive forces holding
two roofing components in intimate contact.
Boot: covering of flexible material, which may
be preformed to a particular shape, used to seal around a penetration.
Brooming: embedding a ply of roofing material by
using a broom to smooth out the ply and ensure contact with the adhesive
under the ply.
BTU:
(British Thermal Unit) - the heat energy required to raise the
temperature of 1 pound of water 1 degree Fahrenheit.
Buckle: an upward, elongated tenting
displacement of a roof membrane frequently occurring over insulation or
deck joints. A buckle may be an indication of movement within a roof
assembly, and usually associated with improper installation.
Built-up Roof Membrane: a continuous,
semi-flexible roof membrane assembly, consisting of plies of saturated
felts, coated felts, fabrics or mats between which alternate layers of
bitumen are applied, generally surfaced with mineral aggregate,
bituminous materials, or a granule-surfaced roofing sheet.
(Abbreviation: BUR.)
Butyl:
a rubber like material produced by copolymerizing isobutylene with a
small amount of isoprene, Butyl may be manufactured in sheets, or
blended with other elastomeric materials to make sealants and adhesives.
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C
Cant Strip: a beveled strip of wood or wood fiber that fits
into the angle formed by the intersection of a horizontal surface and a
vertical surface. The 45-degree slope of the exposed surface of the cant
strip provides a gradual angular transition from the horizontal surface
to the vertical surface.
Capillary: the action by which the surface of a
liquid (where it is in contact with a solid) is elevated or depressed,
depending upon the relative attraction of the molecules of the liquid
for each other and for those of the solid.
Cap Sheet: a granule-surfaced coated sheet used
as the top ply of a built-up roof membrane or flashing.
Caulking: a composition of vehicle and pigment,
used at ambient temperatures for filling joints, that remains plastic
for an extended time after application.
CPE (PolyChlorinated
ethylene): a thermoplastic material, used for single ply roof
membranes, composed of high molecular weight polyethylene which has been
chlorinated.
Chlorosulfonated Polyethylene (CSPE or CSM) (Hypalon):
a synthetic, rubber like thermoset material, based upon high molecular
weight polyethylene with suphonyl chloride, usually formulated to
produce a self vulcanizing membrane.
Coal Tar Bitumen: a dark brown to black,
semi-solid hydrocarbon formed as a residue from the partial evaporation
or distillation of coal tar. It is used as the waterproofing agent in
dead-level or low-slop built-up roofs. It differs from COAL TAR PITCH in
having a lower front-end volatility.
Coal Tar Felt: See TARRED FELT.
Coal Tar Pitch: A
dark brown to black, semi-solid hydrocarbon formed as a residue from the
partial evaporation or distillation of coal tar. It is used as the
waterproofing agent in dead-level or low-slope built-up roofs. (For
specification properties, see ASTM Standard D 450, Types 1 and II.)
Coated Base Sheet: a felt that has been
impregnated and saturated with (or felt) asphalt and then coated on both
sides with harder, more viscous asphalt to increase its impermeability
to moisture; a parting agent is incorporated to prevent the material
from sticking to the roll.
Cold Process: a continuous, semi-flexible roof
membrane, consisting Roofing: of plies of felts, mats or fabrics that
are laminated on a roof with alternate layers of cold-applied roof
cement and surfaced with a cold-applied coating.
Condensation: the conversion of water vapor or
other gas to liquid as the temperature drops or the atmospheric pressure
rises. (See Dew-Point.)
Coping: the covering piece placed on top of a
wall that is exposed to the weather. It is usually sloped to shed water.
Counter flashing: 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
associated fasteners.
Course: (1) the term used for each application
of material that form the waterproofing system or the flashing; (2) one
layer of a series of materials applied to a surface (i.e., a five-course
wall flashing is composed of three applications of mastic with one ply
of felt sandwiched between each layer of mastic.)
Coverage: the surface (in square feet) to be
continuously coated by a specific roofing material, with allowance made
for a specific lap.
CPE: see chlorinated polyethylene
Crack: a separation or fracture occurring in a
roof membrane or roof deck generally caused by thermally induced stress
or substrate movement.
Creep: the permanent deformation of a roofing
material of roof system caused by the movement of the roof membrane that
results from continuous thermal stress or loading.
Cricket: a superimposed construction placed in a
roof area to assist drainage.
CSPE: see chlorosulfonated polyethylene
Curb: a raised member used to support roof
penetrations, such as skylights, mechanical equipment, hatches, etc.
above the level of the roof surface.
Cutback: any bituminous roofing material that
has been solvent thinned. Cutbacks are used in cold-process roofing
adhesives, flashing cements, and roof coating.
Cutoff: A material seal that is designed to
prevent lateral water movement into the edge of a roof system where the
membrane terminate at the end of day's work or used to isolate section
of the roof system. Cutoffs are usually removed before the continuation
of work.
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D
Damp proofing: treatment of a surface or structure to resist
the passage of water in the absence of hydrostatic pressure.
Dead Level: the term used to describe an
absolutely horizontal roof. Zero slope. (See SLOPE.)
Dead Level Asphalt: a roofing asphalt that has a
softening point of 140F (60C) and that conforms to the requirements of
ASTM Standard D 312, Type 1.
Dead Loads: non-moving rooftop loads, such as
mechanical equipment, air conditioning units, and the roof deck itself.
Deck: the structural surface to which the
roofing or waterproofing system (including insulation) is applied.
Degradation: a deleterious change in the
chemical structure, physical properties, or appearance of a material due
to natural or artificial exposure.
Delamination: separation of the plies in a roof
membrane system or separation of laminated layers of insulation.
Dew Point: the temperature at which water vapor
starts to condense in cooling air at the existing atmospheric pressure
and vapor content.
Drain: a device that allows for the flow of
water from a roof area.
Dropback: a reduction in the softening point of
bitumen that occurs when bitumen is heated in the absence of air. (See
SOFTENING POINT DRIFT.)
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E
Edge Sheets: felt strips that are cut to widths narrower that
the standard width of the full felt roll. They are used to cover joints.
Edge Stripping:
application of felt strips cut to narrower widths than the normal width
of the full felt roll.
Edge Venting: the
practice of providing regularly spaced protected openings along a roof
perimeter to relieve moisture vapor pressure.
EIP: Ethylene Interpolymer
Elastomer: a macromolecular material that
returns rapidly to its approximate initial dimensions and shape after
substantial deformation by a weak stress and the subsequent release of
that stress.
Elastomeric: the term used to describe the
elastic, rubber like properties of a material.
Embedment: (1) the process of pressing a felt,
aggregate, fabric, mat, or panel uniformly and completely into hot
bitumen or adhesive; (2) the process of placing a material into another
material so that it becomes an integral part of the whole material.
Emulsion: the intimate dispersion of an organic
material and water achieved by using a chemical or clay emulsifying
agent.
End Lap: the distance of overlap where one ply
extends beyond the end of the immediately adjacent ply.
Envelope: a continuous felt fold formed by
wrapping and securing a portion of a base felt back up and over the felt
plies above it. The envelope is intended to prevent bitumen seepage from
the edge of the membrane.
EPDM: Ethylene Propylene Diene Monomer (commonly
referred to as a "rubber roof")
Epoxy: a class of synthetic, thermosetting
resins that produce tough, hard, chemical-resistant coatings and
adhesives
Equilibrium Moisture Content (EMC): (1) the
moisture content of material stabilized at a given temperature and
relative humidity, expressed as percent moisture by weight; (2) the
typical moisture content of a material in any given geographical area.
Equiviscous Temperature (EVT): the temperature
at which bitumen attains the proper viscosity for built up membrane
application.
Expansion Joint: a structural separation between
two building elements designed to minimize the effect of the stresses
and movements of a building's components and to prevent these stresses
from splitting or ridging the roof membrane.
Exposure: (1)the transverse dimension of a
roofing element not overlapped by an adjacent element in any roof
system. The exposure of any ply in a membrane may be computed by
dividing the felt width minus 2 inches by the number of shingled plies;
thus, the exposure of a 36-inch-wide felt in a shingled, four-ply
membrane should be 8 1/2 inches; (2) the time during which a portion of
a roofing element is exposed to the weather.
Extrusion: a manufacturing process which
consists of forcing batched and formulated material through an orifice.
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F
Fabric: a woven cloth of organic or inorganic filaments,
threads, or yarns.
Factory Mutual: an
organization that classifies roof assemblies for their fire
characteristics and wind-uplift resistance for insurance companies in
the United States.
Felt: a fabric manufactured from vegetable fibers
(organic felts), asbestos fibers (asbestos felts), or glass fibers
(glass fiber felts). The manufacturer process involves mechanically
interlocking the fibers of the particular felt material in the presence
of moisture and heat.
Ferrule: a small metal sleeve placed inside a gutter at
the top. A spike is nailed through the gutter into the fastening board.
The ferrule acts as a spacer in the gutter to maintain its original
shape.
Fine Mineral Surfacing: a water soluble, inorganic
material, more than 50 percent of which passes through the No. 35 sieve,
that may be used on the surface of roofing material.
Fishmouth: Membrane defect consisting of an opening in
the edge lap of a felt in a built up membrance; a consequence of an edge
wrinkle.
Flashing: components used to weatherproof or seal the
roof system edges at the perimeters, penetrations, walls and other
places where the roof covering is interrupted or terminated.
Flashing Cement: a trowelable mixture of cutback
bitumen and mineral stabilizers, including asbestos or other inorganic
fibers.
Flat Asphalt: a roofing asphalt that has a softening
point of approximately 170F (77C) and that conforms to the requirements
of ASTM Standard D 312, Type II.
Flood Coat: the top layer of bitumen into which the
aggregate is embedded on an aggregate-surfaced built up roof.
Fluid Applied Elastomer: as elastomeric material, which
is fluid at ambient temperature, that dries or cures after application
to form a continuous membrane.
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G
Glass Fiber Felt: A felt sheet in which glass fibers are bonded
into the felt sheen with resin. Glass fiber felts are suitable for
impregnation and coating. They are used in the manufacture and coating
of bituminous waterproofing material, roof membranes, and shingles.
Glass Fiber Mat: a thin mat composed of glass fibers
with or without a binder.
Glaze Coat: (1) the top layer of asphalt in a
smooth-surfaced built up roof assembly; (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.
Gravel: coarse, granular aggregate, containing pieces
approximately 5/8 inch to 1/2 inch in size and suitable for use in
aggregate on built up roofs.
Gravel Stop: a flange devices, frequently metallic, designed to
provide a continuous finished edge for roofing materials and to prevent
loose aggregate form washing off of the roof.
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H
Heat Welding: method of melting or fusing together the
overlapping edges of separate sheets of thermoplastics and polymer
modified bitumens.
Headlap: the minimum distance, measured at 90 degrees
to the eaves along the face of a shingle or felt, form the upper edge of
the shingle or felt to the nearest exposed surface.
Holiday: an area where a liquid applied material is missing.
"Hot Stuff"or "Hot": the roofer's term for hot bitumen
Hygroscopic: the term used to describe a material which
attract, absorbs and retains atmospheric moisture.
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I
Incline: the slope of a roof expressed either in percent or in
the number of vertical units of rise per horizontal unit of run.
Infrared Thermography: a practice of roof analysis
where an infrared camera is used to measure the temperature differential
of a roof surface to locate areas of underlying moisture.
Inorganic: being or composed of matter other than
hydrocarbons and their derivatives, or matter hat is not of plant or
animal origin.
Insulation: a material applied to reduce the flow of
heat.
Inverted Roof Membrane Assembly (IRMA): a patented,
proprietary variation of the "Protected Membrane Roof Assembly" in which
Stryofoam Brand insulation and ballast are placed over the roof
membrane. IRMA and Stryofoam are registered trademarks of the Dow
Chemical Corporation.
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L
Lap: that part of a roof or flashing that overlaps or covers
any portion of the same or another type of adjacent component.
Lead: a soft workable metal used for miscellaneous
flashings.
Life cycle costing: a method of economic analysis that
takes into account expected costs over the useful life of an asset.
Lift: the sprayed polyurethane foam that results from a
pass. It is usually with a certain mass thickness and has a bottom
layer, center mass, and a top skin in its make up.
Light reflectance: the percentage of light that is not
absorbed by the surface of the material.
Live Loads: temporary loads that the roof structure
must be designed to support, (e.g., people, installation equipment,
rain, snow, ice, etc.)
Loose laid membranes: membranes that are not attached
to the substrate except at the perimeter. Typically held in place with
ballast.
Low Temperature Flexibility: the ability of a membrane
to remain flexible after it has been cooled to a low temperature.
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M
Manufacturer's Bond: a security company's guarantee that it
will stand behind a manufacturer's liability to finance membrane repairs
occasioned by ordinary wear within a period generally limited to 5, 10,
15, or 20 years.
Mastic: see FLASHING CEMENT or ASPHALT MASTIC.
Mechanically Fastened Membranes: membranes attached at
defined intervals to the substrate.
Membrane: a flexible or semi-flexible roof covering or
waterproofing layer, whose primary function is the exclusion of water.
Metal Flashing: see FLASHING; metal flashing is
frequently used as through wall flashing, cap flashing, counterflashing
or gravel stops.
Mildew: a superficial coating or discoloring of an organic
material due to fungal growth.
Mineral Fiber Felt: a felt with mineral wool as its principal
component.
Mineral Granules: opaque, natural, or synthetically
colored aggregate commonly used to surface cap sheets, granule-surfaced
sheets, and roofing shingles.
Mineral Stabilizer: a fine, water-insoluble inorganic
material, used in a mixture with solid or semi solid bituminous
materials
Mineral Surfaced Roofing: built up roofing material
whose top ply consists of granule surfaced sheet.
Mineral Surfaced Sheet: a felt that is coated on one or
both sides with asphalt and surfaced with mineral granules.
Modified Bitumen: composite sheets consisting of a
polymer (e.g., atactic polypropylene (APP), or styrene butadiene styrene
(SBS)) often reinforced and sometimes surfaced with various types of
mats, films, foils and mineral granules.
Moisture Relief Vent: venting device through the
roofing membrane to relieve moisture vapor pressure from within the roof
assembly.
Mole Run: a meandering ridge in a roof membrane not associated
with insulation or deck joints.
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, are coated with
adhesive and are then turned over and applied to the substrate.
Mopping: an application of hot bitumen applied to the
substrate or to the felts of a built up roof membrane with a mop or
mechanical applicator.
..........Solid Mopping: a
continuous mopping of a surface, leaving no unmopped areas.
..........Spot Mopping: a
mopping pattern in which hot bitumen is applied in roughly circular
areas,
..........leaving a grid of
unmopped, perpendicular bands on the roof.
..........Strip Mopping: a
mopping pattern in which hot bitumen is applied in parallel bands.
Mud Cracking: surface cracking of surface material
resembling dried cracked earthen mud.
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N
Nailing: (1) in the Exposed Nail Method, nail heads are exposed
to the weather; (2) in the Concealed Nail Method, nail heads are
concealed from the weather.
Neoprene: a synthetic rubber (polychloroprene) used in
liquid-applied and sheet applied elastomeric roof membranes or
flashings.
Night Seal: method used to temporarily seal a membrane
edge during construction to protect the roof assembly from water
penetration.
Nineteen-Inch Selvage: a prepared roofing sheet with a
17-inch granule surfaced edge. This material is sometimes referred to as
SIS or as Wide-Selvage Asphalt Roll Roofing Material Surfaced with
Mineral Granules.
Ninety-Pound: a prepared organic felt roll with granule
surfacing what has a mass of approximately 90 pounds per 100 square
feet.
Nitrile Rubber: a membrane whose predominant resinous
ingredient is a synthetic rubber made by the polymerization of
acrylonitrile with butadiene.
Non-Friable: a material that, when dry, cannot be
crumbled, pulverized or reduced to powder by hand pressure.
Non-Vulcanized Membrane: a membrane manufactured from
thermoplastic compounds that retain its thermoplastic properties
throughout its service life.
Nuclear Testing: a device that contains a radioactive
source to emit high velocity neutrons into a roof system. Reflected
neutrons are measured to ascertain presence of moisture.
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O
Orange Peel: a surface condition that shows a fine texture
resembling the texture of an orange.
Organic: being or composed of hydrocarbons or their
derivatives, or matter of plant, or animal origin.
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P
Parapet Wall: perimeter wall, which extends above the roof.
Peel Strength: average force required to peel a
membrane from the substrate to which it has been bonded.
Penetration: any object passing through the roof.
Perlite: an aggregate used in lightweight insulation
concrete and in preformed perlitic insulation board, formed by heating
and expanding siliceous volcanic.
Perm: a unit of water vapor transmission defined as 1
grain of water vapor per square foot per hour per inch of mercury
pressure difference (1 inch of mercury = 0.491 psi). The formula for
perm is: P = GRAINS OF WATER VAPOR/SQUARE FOOT * HOUR * INCH MERCURY
Permeance: an index of a material's resistance to water
vapor transmission. (See PERM.)
Phase Application: the installation of a roof system or
waterproofing system during two or more separate time intervals.
Phenolic: a rigid closed-cell foam product with an
orange or light red foam core, sandwiched between various types of
facers. Problems have been reported with board shrinkage, and corrosion
of adjacent metal roof assembly components. (Contact IRC staff for
further information and details.)
Picture Framing: a rectangular pattern of ridges in a
roof membrane over insulation or deck joints.
Pitch Pocket: a flange, open bottomed, metal container
placed around columns or other roof penetration that is filled with hot
bitumen and/or flashing cement to seal the joint.
Plastic Cement: see FLASHING CEMENT
Ply: a layer of felt in a built up roof membrane
system. A four-ply membrane system has four plies felt. The dimension of
the exposed surface (the "exposure") of any ply may be computed by
dividing the felt width (minus 2 inches) by the number of plies; thus,
the exposed surface of a 36 inch wide felt in a four ply membrane should
be 8 1/2 inches. (See EXPOSURE.)
Pond: a roof surface that is incompletely drained.
Positive Drainage: the drainage condition in which
consideration has been made for all loading deflection of the deck, and
additional roof slop has been provided to ensure complete drainage of
the roof area within 24 hours of rainfall.
Pourable Sealer: a type of sealant often supplied in
two parts and is typically used to fill pitch pans.
Protected Membrane Roof (PMR): an insulated and
ballasted roof assembly, in which the membrane is covered by the
insulation and ballasted (sometimes referred to as an "inverted roof
assembly").
Psychometric Chart: a diagram relating to the
properties of humid air with temperature.
Primer: a thin, liquid bitumen applied to a surface to improve
the adhesion of subsequent application of bitumen.
PVC: Polyvinyl Chloride – Usually associated with a
thermoplastic single ply roof membrane system.
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R
R-Value: the resistance to heat transfer of a material.
Rake: the sloped edge of a roof at the first or last
rafter.
Reflectivity: the ability of the surface of a material
to reflect the infra red energy of a light source.
Reglet: a groove in a wall or other surface adjoining a
roof surface for use in the attachment of counterflashing.
Reinforced Membrane: a roofing or waterproofing
membrane reinforced with felts, mats, fabrics, or chopped fibers.
Relative Humidity: the ratio of the weight of moisture
in a given volume of air vapor mixture to the saturated (maximum) weight
of water vapor at the same temperature, expressed as a percentage. For
example, if the weight of the moist air is 1 pound and if the air could
hold 2 pound of water vapor at a given temperature, the relative
humidity (RH) is 50 percent.
Reroofing: the practice or applying new roofing
material over existing roofing materials.
Ridging: an upward, "tenting" displacement of a roof
membrane, frequently occurring over insulation joints, deck joints and
base sheet edges. Generally associated with improper application. (See
picture framing)
Roll Roofing: the term applied to smooth surfaced or
mineral surfaced coated felts.
Roof Assembly: an assembly of interacting roof
components (including the roof deck) designed to weatherproof and,
normally, to insulate a building's top surface.
Roof System: a system of interacting roof components
(NOT including the roof deck) designated to weatherproof and, normally,
to insulate a building's top surface.
Rubber: a polymeric material, which, at room
temperature, is capable of recovering substantially in shape and size
after removal of force.
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S
Saturated Felt: a felt that has been partially saturated with
low softening point bitumen.
SBS: See Styrene Butadiene Styrene
Screen: an apparatus with apertures for separating
sizes of material.
Seal: (1) a narrow closure strip made of bituminous
materials; (2) to secure a roof from the entry of moisture.
Sealant: a mixture of polymers, fillers, and pigments
used to fill and seal joints where moderate movement is expected; it
cures to a resilient solid.
Self –Adhering Membrane: a membrane that can adhere to a
substrate and to itself without use of adhesives. The undersurface is
protected by a release paper.
Selvage: an edge or edging that differs from the main
part of (1) a fabric, or (2) granule-surfaced roll roofing material.
Selvage Joint: a lapped joint designed form mineral
surfaced cap sheets. The mineral surfacing is omitted over a small
portion of the longitudinal edge of the sheet below in order to obtain
better adhesion of the lapped cap sheet surface with the bituminous
adhesive.
Shark Fin: an upward curled felt side or lap or end
lap.
Shingle: (1) a small unit of prepared roofing material
designed to be installed with similar units in overlapping rows on
inclines normally exceeding 25 percent; (2) to cover with shingles; (3)
to apply any sheet material in overlapping rows like shingles.
Shingling: (1) the procedure of laying parallel felts
so that one longitudinal edge of each felt overlaps and the other
longitudinal edge underlaps, an adjacent felt. (See PLY.) Normally,
felts are shingled on a slope so that the water flows over rather than
against each lap; (2) the application of shingles to a sloped roof.
Sieve: an apparatus with apertures for separating sizes
of material.
Slag: a hard, air-cooled aggregate that is left as
residue from blast furnaces. It is used as a surfacing aggregate and
should be surface dry and free of sand, clay, or other foreign
substances at the time of application.
Slip Sheet: a sheet material placed between two
components of a roof assembly to ensure that no adhesion occurs between
them, and/or to prevent possible damage from chemical incompatibility,
wearing or abrasion of the membrane. Often associated with PVC
membranes.
Slippage: the relative lateral movement of adjacent
components of a built up roof membrane. It occurs mainly in roof
membranes on a slope, sometimes exposing the lower plies to the weather.
Slope: the tangent of the angle between the roof
surface and the horizontal. It is measured in inches per foot. The
Asphalt Roofing Manufacturers Association (ARMA) ranks slopes as
follows:
..........Level Slope: up
to 1/2 inch per foot
..........Low Slope: 1/2
inch per foot to 1 1/2 inches per foot
Steep Slope: over 1 1/2 inches per foot
Smooth Surfaced Roof: a built up roof membrane surfaced
with a layer of hot mopped asphalt, cold applied asphalt clay emulsion,
cold applied asphalt cutback, or sometimes with an unmopped inorganic
felt.
Snow Load: a load imposed on buildings due to snowfall.
(Categorized as live or environmental load.)
Softening Point Drift: a change in the softening point
of bitumen during storage or application. (See Dropback)
Soil Stack: a sanitation pipe that penetrates the roof
– used to vent plumbing fixtures. (Stink Stacks)
Solid Mopping: see Mopping
Solvent Welding: a process where a liquid solvent is
used to chemically weld or join together two or more layers of certain
membranes (usually thermoplastics).
Spot Mopping: see Mopping
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.
Sprinkle Mopping: see Mopping
Square: the term used to describe 100 square feet of
roof area.
Stack Vent: a vertical outlet in a built up roof system
designed to relieve any pressure exerted by moisture vapor between the
roof membrane and the vapor retarder or deck.
Standing Seam: a metal roof system that consists of an
overlapping or interlocking seam that occurs at an upturned rib.
Steep Asphalt: a roofing asphalt that has a softening
point of approximately 190F (88C) and that conforms to the requirements
of ASTM Standard D 312, Type III.
Strawberry: a small bubble or blister in the flood
coating of gravel surfaced roof membrane.
Stress Crack: external or internal cracks within a
material caused by long-term stress.
Strip Mopping: see MOPPING
Stripping: (1) the technique of sealing a joint between
metal and Strip Flashing the built up roof membrane with one or two
plies of felt and hot applied or cold applied bitumen; (2) the technique
of taping joints between insulation boards on deck panels.
Styrene Butadiene, Styrene Copolymer (SBS): high
molecular weight polymers that have both thermoset and thermoplastic
properties formed by the block copolymeriztion of styrene and butadiene
monomers. These polymers are used as the modifying compound in SBS
polymer modified roofing membranes to impart rubber like qualities to
the asphalt.
Substrate: the surface upon which the roofing or
waterproofing membrane is applies (i.e. the structural deck or
insulation).
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.
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T
Tapered Edge Strip: a tapered insulation strip used to (1)
elevate the roof at the perimeter and at curbs that extend through the
roof; (2) provide a gradual transition from one layer of insulation to
another.
Taping: see STRIPPING.
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 materials.
Tarred Felt: a felt that has been saturated with
refined coal tar.
Tear Off and Reroof: the removal of all roof system
components down to the structural deck followed by the installation of a
new roof system.
Tear Strength: the maximum force required to tear a specimen.
Test Cut: a sample of the roof membrane, usually 4
inches x 40 inches in size, that is cut from a roof membrane to:
..........* Determine the
weight of the average interply bitumen poundage
..........* Diagnose the
condition of the existing membrane (e.g., to detect leaks or blisters).
Thermal Conductance (C): a unit of heat flow that is
used for specific thickness of material or for materials of combination
construction, such as laminated insulation.
Thermal Conductivity (k): the heat energy that will be
transmitted by conduction through 1 square foot of 1 inch thick
homogeneous material in one hour.
Thermal Insulation: a material applied to reduce the
flow of heat
Thermal Resistance: an index of material applied to
reduce the flow of heat.
Thermal Shock: the stress producing phenomenon
resulting from sudden temperature changes in a roof membrane. (For
example, when a rain shower follows brilliant, hot sunshine.)
Thermoplastic: materials that soften when heated and
harden when cooled.
Thermoplastic Olefin Membrane (TPO): a blend of
polypropylene and ethylene-propylene polymers. Colorant, flame retarants,
UV absorbers, and other proprietary substances, which may be blended
with the TPO to achieve the desired physical properties.
Thermoset: a material that solidifies or "sets"
irreversibly when heated. This property is usually associated with
cross-linking of the molecules induced by heat or radiation.
Through Wall Flashing: a water resistant membrane or
material assembly extending through a wall and its cavities, positioned
to direct any water entering the top of the wall exterior.
Tie-Off: a seal used to terminate a roofing application
at to the adjacent roofing system.
TPO: See Thermoplastic Olefin.
Tuckpointing: 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
Underwriters Laboratories: an organization that classifies roof
assemblies for their fire characteristics and wind uplift resistance for
insurance companies in the United States.
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V
Vapor Migration: the movement of water vapor from a region of
high vapor pressure to a region of lower vapor pressure.
Vapor Pressure Gradient: a graph, analogous to a
temperature gradient, indicating the changes in water vapor pressure at
various cross sectional planes through a roof or wall system.
Vapor Retarder: a material designed to restrict the
passage of water vapor through a wall or roof. In the roofing industry,
a vapor retarder should have a perm rating of 0.5 or less.
Vent: an opening designed to convey water vapor or
other gas from inside a building or a building component to the
atmosphere, thereby relieving vapor pressure.
Vermiculite: an aggregate used in lightweight
insulation concrete, formed by the heating and consequent expansion of a
micaceous mineral.
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W
Water Cutoff: see CUTOFFS.
Waterproofing: treatment of a surface or structure to
prevent the passage of water under hydrostatic pressure.
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