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.
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.
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.
see
FLASHING
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.
PolyChlorinated
ethylene (CPE): 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.
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.)
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.
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
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.
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.
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.
"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.
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.
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.
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:
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.
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.
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.
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
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.
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.
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.
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.
Underwriters
Laboratories: an organization that classifies roof assemblies for their fire
characteristics and wind uplift resistance for insurance companies in the
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.
Water
Cutoff:
see CUTOFFS.
Waterproofing:
treatment of a surface or structure to prevent the passage of water under
hydrostatic pressure.