Appendix C - Glossary

This glossary was provided and used with permission by the Canadian Roofing Contractors Association.

A-frame
a portable frame built in the shape of a letter “A” and used by roofers to hoist materials.
Adhere
to cause two surfaces to be held together by the combined strength of the molecular forces and the mechanical interlocking achieved between adhesive and the bonded surface. See adhesion.
Adhesion
1. The degree of attachment between two surfaces held together by interfacial forces – mechanical or chemical or both:
2. the degrees of attachment or bonding between application of the same substance.
3. the combined ultimate strength of the molecular forces and the mechanical interlocking achieved between the adhesive and the surface bonded. Adhesion is measured in shear and peel modes.
Adhesive
A cementing substance that produces a steady and firm attachment or adhesion between two surfaces. Adhesion is measured in shear and peel modes.
Aggregate
1. Crushed stone, crushed slag, or water-worn or natural gravel used as protective surfacing or ballast in a roof system.
2. Any granular mineral material. 3. Roofing gravel in built-up roofing (BUR).
Aggregate, lightweight (LWA):
Aggregate of low density; examples include coal bottom ash, pumice, scoria, volcanic cinders, tuff and diatomite; expanded or sintered clay, shale, slate, diatomaceous shale, perlite, vermiculite or slag and bonded or sintered coal combustion products (CCPs) used to produce lightweight concrete or component products.
Air barrier
An assembly of materials or building element used in building construction that provides resistance to the movement of air into and out of the building.
Alligatoring
Hardening and shrinking of exposed bitumen coatings due to oxidation, that produces small islands of bitumen between deep cracks and gives the appearance of alligator hide.
Aluminum
A non-rusting, malleable metal sometimes used for metal roofing and flashing.
Alloys, polymeric
A blend of two or more polymers, e.g. a rubber and a plastic, to improve properties such as impact strength.
Application
The act of putting on or building up the felts and flashings of all elements of any roofing system. The materials may be hot or cold fluids or adhesives or prefabricated sheets.
Application temperature
The temperature of the hot materials such as asphalt when applied to the roof. See also equiviscous temperature (EVT).
Architectural shingle
An asphalt shingle that provides a dimensional appearance. See dimensional shingle.
Asbestos
A group of natural, fibrous impure silicate materials.
Asphalt
A bituminous brown to black material derived from the distilling of crude oil, commonly left as a residue after evaporating or otherwise processing crude oil or petroleum. See bitumen.

Asphalt may be further refined to provide a wide range of viscosities and softening points required for this end use e.g. shingles, BUR for different slopes etc. as per the following grade specifications:
  • Type 1 -  asphalt for use on built-up roofs with slopes less than or equal to 1:16 (6.25⁰) and for use as waterproofing below ground level when not exposed to surface temperatures above 25°C (77°F).
  • Type 2 -  asphalt for use on built-up roofs with slopes less than or equal to 1:8 (12.5⁰) and for use as waterproofing above ground level on vertical surfaces not exposed to direct sunlight.
  • Type 3 - asphalt for use on built-up roofs with slopes greater than 1:8 (12.5⁰) for exposed applications or for use as waterproofing above ground level on vertical surfaces not exposed to direct sunlight.
Asphalt emulsion
A mixture of asphalt particles and emulsifying agent, such as bentonite clay or soap, and water.
Asphalt felt
An asphalt-saturated and/or asphalt-coated organic or inorganic felt. See also felt.
Asphalt mastic
A mixture of asphaltic material and graded mineral aggregate that can be poured when heated, but requires mechanical manipulation to apply.
Asphalt roof cement
A trowelable mixture of solvent-based bitumen, mineral stabilizers, other fibers and/or fillers.
Asphalt shingle
A shingle manufactured by coating a reinforcing material (paper felt or fibreglass mat) with an asphalt-based coating and having mineral granules on the side exposed to the weather. See shingle.
Atactic polypropylene (APP)
High-molecular-weight polymer formed by the polymerization of propylene and characterized by random arrangement of the side methyl groups around the chain backbone.
Attic
The cavity or open space above the ceiling and immediately under the roof deck of a building.
Bird Bath
Random, inconsequential amounts of residual water on a roof membrane.
Bitumen
A generic term applied to mixtures of predominantly hydrocarbons in viscous or solid form, derived from coal or petroleum. The roofing industry uses it to describe either coal tar pitch or asphalt and used as an adhesive and waterproofing agent.
Bituminous emulsion
1. A suspension of minute globules of bituminous material in water of in an aqueous solution.
2. A suspension of minute globules of water or of an aqueous solution in a liquid bituminous material (invert emulsion).
Blister
An enclosed raised spot or area containing gas or liquid that shows on the surface of prepared and built-up roofing. Small blisters confined to the surface are called weather blisters, rash blisters, pimpling or blueberries. The larger, more serious and usually more evident blisters are structural blisters. These blisters are spongy to the touch and may occur between any of the layers of roofing felt or between membrane and deck or insulation.
Bonding adhesive
the adhesive required to adhere a single ply membrane to its substrate.
Boot
A bellows-type covering to exclude dust, dirt, moisture, etc, from a flexible joint. It is used for making a watertight joint around a roof penetration.
Brace
A piece of wood or other material that holds anything tightly or supports it firmly; a prop.
Brooming
Embedding a ply by using a broom to smooth it out and ensure contact and adhesion with the underlying substrate.
Built-up Roofing (BUR)
A continuous, semi-flexible membrane consisting of plies of saturated felts, coated felts, fabrics or mats assembled in place with alternate layers of bitumen, and surfaced with mineral aggregate, or coating for protection from solar radiation. May include modified bitumen membrane system of more than one ply.
Burner
An apparatus that emits flame used to heat a kettle or to dry off roofs.
Butt Joint
A joint formed by adjacent, separate sections of material, such as where two neighbouring pieces of insulation abut.
Butyl rubber
A synthetic rubber based on isobutylene and minor amount of isoprene.
Cap sheet
1. The top ply of a built-up roofing membrane acting as the finished surface of a roof.
2. Any mineral-surfaced or other coated felt or sheet designed to provide waterproofing and weatherability.
3. The finishing layer in a modified bitumen roof membrane system.
Caulking
Any of a wide range of bituminous, rubber, plastic or other materials suitable for filling seams or cracks to make them tight against water leakage and remain plastic for an extended time after application. See also sealant.
Cement
A substance used to make objects adhere to each other. In the roofing industry loosely applied to mean caulking and mastic.
Chalk line
Heavy string or cord used for lining purposes.
Coal tar
Tar derived from the destructive distillation of coal during the conversion of coal into coke.
Coal tar pitch
A bituminous material from the heavy end of the distillation of crude coal tar produced from the coking of coal.
Coated base sheet
1. An asphalt felt coated on one or both sides with harder, more viscous asphalt and surfaced with mineral matter of various sizes.
2. A glass fibre felt that has been simultaneously impregnated and coated with asphalt on both sides. These products come under the group of roll roofing.
Coating
A thin layer of a substance used to cover other materials, to provide an aesthetic or protective function.
Cold process roofing
A continuous, semi-flexible membrane consisting of plies of felts, mats, or fabrics laminated on a roof with alternate layers of roof cement and surfaced with a cold-applied coating.
Collar
A metal cap flashing around a vent pipe projecting above a roof deck.
Compatible materials
Two or more materials or substrates that can be mixed, blended or attached without separating, reacting or affecting the materials adversely.
Compound
An intimate admixture of a polymer with all the ingredients necessary for the properties required of the final product.
Condensation
The change from water vapour to liquid water, resulting from a drop in temperature of an air vapour mixture.
Core sampling
A cylindrical sample taken from the roof.
Course
A continuous row or layer of shingles or other roofing materials.
Cover Board
Thin, normally homogeneous materials formed into boards and used over roof insulation to provide protection to the insulation during installation and service and to enhance the performance of the roofing assembly.
Coverage
1. The area to be covered per unit volume of coating to obtain a specified dry thickness.
2. Area covered by a unit of roofing such as a bundle of shingles of a roll of roofing.
Crack
A break in a roofing membrane as a result of flexing, often at a ridge or wrinkle.
Cricket
A small false roof or an elevated part of the roof that is designed to channel surface water from behind an obstacle, such as a chimney, to drains. Frequently located in a valley, a cricket is often constructed like a small hip roof, or like a pyramid with a diamond shaped base. Also called a saddle.
Curb
A low wall of wood, masonry or metal built above the level of the roof, surrounding roof openings or supporting mechanical equipment.
Cured
Completed dry; moisture free.
Curing
To change the properties of a polymeric system into a more stable, usable condition by the use of heat, radiation, or reaction with chemical additives. See also cross linking and vulcanization.
Dampproofing
The treatment of a building material or component surface with a bituminous or other coating to provide some measure of resistance to the passage of moisture into or through the material or components.
Deck
The structural surface to which the roofing or waterproofing system is applied. See also Structural roof deck.
Deflection
1. The downward displacement of a structural member or system under load.
2. The change in mid-span position of a test specimen during a creep test.
Delamination
1. Separation of components within a system as a result of cohesive or adhesive failure.
2. Separation of the laminated layers of a component or system.
Detail
One of the many minor parts into which a building may be divided; a drawing of such a part.
Dipper
A ladle for pouring bitumen.
Drain
An outlet to allow water to flow from a surface into a drain pipe and away from the building through a drainage system.
Drip edge
The formed edge on metal flashing used at the eaves or other roof details to encourage water to drip away from vertical surfaces of the building detail.
Dunnage
Loose matting used to support and keep cargo in place.
Eave
The projecting lower edge of a roof. That part of a roof which projects beyond the wall.
Eaves flashing
The treatment of the edge of a roof with felt and metal flashing. The portion of the metal eaves flashing exposed on the elevation may be called a fascia flashing.
Elastomer
A macromolecular material that returns rapidly to its appropriate initial dimensions and shape, after substantial deformation by a low level of stress and the release of that stress.
Embedment or Embed
1. The process of pressing a felt, aggregate, fabric, mat or panel uniformly and completely into hot bitumen or adhesive to ensure intimate contact at all points.
2. The process of pressing granules into coating in the manufacture of factory-prepared roofing, such as shingles, roll roofing.
Emulsion
An intimate mixture of bitumen and water, with uniform dispersion of the bitumen or water gobules, usually stabilized by an emulsifying agent or system. When the water evaporates, the bitumen particles cement together.
End lap
The amount of overlap at the start of a roll of felt over the end of the previously laid roll.
Envelope
1. The practice of carrying the air/vapour barrier or other waterproofing sheet up and onto the top surface of the insulation in a compact roofing system.
2. 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 tip of the membrane. The envelope prevents bitumen seepage from the edge of the membrane.
Equiviscous temperature (EVT)
The temperature at which bitumen will have the optimum viscosity for spreading at the required rate in roofing application.
Mop application
The temperature at which the asphalt's apparent viscosity is 0.125 Pa s (125 centipoise).
Equiviscous temperature (EVT) for asphalt
The recommended EVT for roofing asphalt as follows:
Ethylene Propylene Diene Monomer (EPDM)
A synthetic elastomer based on ethylene, propylene and a small amount of a non-conjugated diene monomer to provide for vulcanization.
Expanded polystyrene (EPS)
Insulation composed principally of polystyrene resin processed to form a rigid foam having a predominantly closed-cell structure. Boards or blocks are formed during expansion. See also insulation.
Exposure
1.The time during which a portion of a roofing element is exposed to any environment; natural or laboratory created.
2. The transverse dimension of a roofing element not overlapped by an adjacent element in any roofing system. The exposure of any ply in a membrane may be computed by dividing the felt width minus 50 mm, by the number of shingled plies; thus, the exposure of a 900 mm (36 in) wide felt in a shingled, four ply membrane should be (900-5)/4 = 213 mm (8.5 in).
Extruded polystyrene (XPS)
Insulation board produced by a continuous extrusion process as the resin foams. This forms a tight and complete skin on each side of the board.
Fabric
1. Geotextile membranes used as a protective or separating layer in roofing and waterproofing systems.
2. A woven cloth of organic or inorganic filaments treated with bitumen and being stronger than felt, used in special flashing applications.
Fall arrest system
an assembly of components joined together so that when the assembly is connected to a fixed support, it is capable of arresting a worker’s fall.
Fascia
Any cover board at the edge or eaves of a flat or sloping overhanging roof.
Felt
A general term used to describe sheet roofing material consisting of a mat of organic or inorganic fibres untreated, saturated, impregnated or saturated and coated with bitumen and supplied in roll form.
Filler
1. Finely-divided mineral matter used as an extender to improve the properties of asphalt coatings for shingle and built-up roofing felts, and bituminous plastic cement or mastic.
2. Different types of fillers are used in some polymeric materials to improve some mechanical properties and also to reduce the cost of the finished product. See also stabilizer.
Filter fabric
a woven inorganic cloth or geotextile used as a filter that allows passage of water while preventing passage or migration of fines particles and soil in a protected membrane or vegetated roof system.
Flashing
A continuation of the roofing proper to cover any element of the roof structure departing from the roof deck incline.
Flash off
The time required for the volatiles in a petroleum-based adhesive/primer to escape into the atmosphere prior to bonding.
Fluid-applied elastomer
An elastomeric material, which is fluid at ambient temperature and that dries or cures after application to form a continuous membrane for roofing and waterproofing.
Gauge
A metal thickness measurement.
Granules
Particles of a graded size that are embedded in the asphalt coating of shingles, mineral-surfaced roofing, and modified bituminous membranes. These granules are opaque, natural, ceramically-coloured aggregates or crushed slags. The slag granules have a glassy or glittery appearance.
Gravel
Small pieces of aggregate larger than sand grains resulting from the natural erosion or the crushing of rock, used to protect bituminous surfaces or ballast in roofing systems
Gravel spreader
A piece of mobile mechanical roofing equipment that dispenses and spreads gravel in one continuous operation.
Growing medium
an engineered blend of organic and inorganic materials specifically designed for the growth of plants in a vegetative roof system.
Guardrail system
an assembly of components joined together to provide a barrier to prevent a worker from falling from the edge of a surface.
Gutter
Trough at the eaves of a roof to convey rain water from the roof to a downspout
Hip
The sloping line along the outer angle formed by the meeting of two sloping sides of a roof whose eaves meet at a right-angle. A hip roof is one that rises by inclined planes from all four sides of a building to form hips at the intersection of adjacent roof slopes.
Hoist
A hoisting machine, to pullup.
Hydrostatic pressure
The pressure equivalent to that exerted on a surface by a column of water of a given height.
Ice dam
A mass of ice formed at the transition from a warm to a cold roof surface. Frequently formed by re-freezing meltwater at the overhang of a sloping roof, an ice dam may cause ice and water to back up and make the surface slippery for snow to slide down.
Incline
The angle made by a roof plane with a horizontal plane. Interchangeable with slow, fall, or pitch.
Inorganic
Being or composed of matter other than hydrocarbons and their derivatives, or matter that is not of plant or animal origin.
Insulation
A material used as part of a building enclosure to retard the flow of heat through the enclosure. It is made from a variety of organic and inorganic fibres and foams, e.g., expanded/extruded polystyrene, glass fibre, cellular glass, phenolic foam, perlite, polyurethane foam, polyisocynurate foam. It can be loose-filled, or used in batt, board or block form. See also roof insulation, board insulation.
Jack
A flanged metal sleeve used as part of the flashing around small items that penetrate a roof.
Joist
One of a number of smaller closely-spaced parallel structural supports for a flat roof deck spanning between walls, roof beams, or purlins, or to support a flat ceiling below a sloping roof.
Kettle
Equipment used for heating bitumen to the temperatures required for application.
Lap
That part of a roofing unit that covers the preceding course in any overlapping roofing application. Applied to shingles, built-up roofing felts, and most other types of roofing. See also exposure.
Loose-laid membrane
A roofing membrane that is attached to the substrate only at the edges and roof penetrations and is ballasted.
Mastic
1. A material of relatively viscous consistency that dries or cures to form a protective finish, suitable for application to thermal insulation in thickness greater than 0.75 mm per coat.
2. Trowelable bituminous paste made by adding mineral fillers to concentrated cutbacks. See also plastic cement, cement and asphalt mastic.
Membrane
A continuous sheet of material whether it is prefabricated as a flexible polymeric sheeting or is sprayed or coated in the field, in single ply or in multiple plies.
Membrane flashing
The vertical extension of the roofing membrane installed at horizontal to vertical junctions at roof penetrations and membrane terminations
Metal flashing
Frequently used as through-the-wall, cap or counter-flashing.
Mini mopper
A small container with wheels that can be pushed along over the roof to dispense bitumen for the laying of roofing felts.
Mop
A tool used for the application of hot bitumen made from a bundle of cotton or other yarn attached to a long wooden handle. Bitumen soaked up and held by it when dipped into a container of hot material is transferred to and spread on the roof.
Organic
Being or composed of hydrocarbons or their derivatives, or matter of plant or animal origin.
Organic felt
Felt made from organic fibres and in particular wood fibres
Overhang
The part of a roof structure that extends beyond the exterior walls of a building.
Overheating
Heating the material in the kettle in such a manner that its characteristics are altered. This alteration could occur by prolonged heating at proper temperature or by heating for shorter periods at higher than recommended kettle temperature.
Parapet
The part of a perimeter wall that extends above the roof.
Penetration
A measure of the hardness related to viscosity of bitumen as determined by an empirical test that gives the depth of penetration of a standard weighted needle vertically into a sample after a definite time and at a particular temperature. It is measured as the distance of penetration in tenths of a millimetre. A cone is sometimes used for special purposes instead of a needle.
Perlite
1. It is produced by heating and expanding silicaceous volcanic glass and is used as loose fill insulation.
2. It is also used as an aggregate in light-weight concrete. 3. It is combined with organic fibres and waterproofing binders to make insulating boards.
Photovoltaic panel
a number of modules that are electrically and mechanically connected and provides a field-installable unit.
Pitch
A black or dark brown solid cementious residue that results from the distillation of tar. A tar derived from coal is referred to as coal tar, and a pitch derived from coal tar as coal tar
Plastic cement
Although all caulking cements could be called plastic cements, there is a commonly held acceptance in the roofing industry that plastic cement means bituminous cement, either asphalt or coal tar based. It is a mixture of bitumen, asbestos fibres, filler and suitable solvent. See also flashing cement.
Ply
A single layer or thickness of roofing material in a roofing membrane. A four-ply membrane has at least four plies of felt at any vertical cross section cut through the membrane.
Polyisocyanurate foam
This insulation material is produced from polyisocyanurate based chemicals. The foam board is sandwiched between asphalt saturated organic or inorganic felt facer sheets.
Polymer
A macromolecular material formed by the chemical combination of monomers having either the same or different chemical composition. Plastics, rubbers, and textile fibres are all high molecular weight polymers.
Polypropylene
A tough, lightweight rigid plastic made by the polymerization of high-purity propylene gas.
Polyurethane (PU):
Insulation composed principally of the catalysed reaction product of polyisocyanurate and polyhydroxy compounds, processes usually with fluorocarbon gas to form a rigid foam having a predominantly closed-cell structure. It is sprayed-in-place or preformed into boards. See also insulation.
Polyvinyl Chloride (PVC)
A synthetic thermoplastic polymer prepared from vinyl chloride. PVC can be compounded into flexible and rigid forms through the use of plasticizers, stabilizers, filler, and other modifiers. The rigid forms are used in pipes, the flexible forms in the manufacture of sheeting for roofing.
Positive 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 drying.
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 seal.
Pour coat
The top layer of bitumen for an aggregate-surfaced built-up roofing membrane, poured or flooded onto the finished felts and over which the aggregate is spread. Also called a pour or a flood coat.
Primer
A thin liquid bitumen applied to a surface to improve the adhesion of heavier applications of bitumen and to absorb dust. The most commonly used is asphalt primer.
Purlin
A horizontal structural member spanning between beams, frames or trusses to support a roof deck or the rafters or joists supporting a roof deck.
Rafter
One of a number of closely spaced structural members of a sloped roof, usually extending from the eaves to a ridge or hip on a small roof or between purlins on larger roofs to carry the roof deck.
Rake
The sloped edge of a roof at the first or last rafter, i.e. at its intersection with a gable.
Re-covering
The process of covering an existing roofing system with a new roofing system.
Reinforcement
A strong inert material bound into asphaltic or polymeric materials to improve its strength, stiffness, and impact resistance. Reinforcements are usually long fibres of glass, sisal, cotton or polymers, in woven or non-woven form. To be effective, the reinforcing material must form a strong adhesive bond with the resin.
Re-roofing
Replacement of all or part of a roofing system.
Ridge
The horizontal line where two opposite sloping sides of a roof join at the highest level of the roof.
Ridge cap
The covering of wood, metal or other roofing material that tops the ridge of a roof.
Roll roofing
Any roofing material that is supplied from the manufacturers in rolls, but more specifically applied to coated felts either smooth or mineral-surfaced used for roofing without additional top coatings or surfacing.
Roof
A construction on top of a building that together with walls forms a separator between inside and outside environments. A roof system is a structurally supported, air, heat, interior moisture and rain control combination.
Roof assembly
An assembly of interacting roof components (including structural roof deck) for weatherproofing and thermal insulation.
Roof covering
The exterior roof cover or skin of the roof assembly, consisting of membrane, panels, sheets, shingles, tiles, etc.
Roofing
1. The material used for constructing a water shedding or waterproofing system.
2. That part of the architectural specifications and building construction contract that deals with the supply and application of roofing materials and systems.
Roofing system
An assembly of interacting components designed to weatherproof, and normally to insulate, a building's top surface.
Roof insulation
Any medium of low-density material suitable and used as part of a roofing system to reduce heat loss or gain through the roof. See also insulation, board insulation.
Roof system
A system in interacting roof components (not including structural roof deck) for weatherproofing and thermal insulation.
Rubber
A polymeric material that, at room temperature, is capable of recovering substantially in shape and size after removal of a deforming force. Refers to both synthetic and natural rubber. Also called an elastomer.
Saddle
A ridge in a roof deck that divides two sloping parts of the surface so that water will be diverted to the roof drains. Usually constructed in a level valley, or behind a projection above a sloping roof. See cricket.
Safety factor
The ratio of the failure load to the specified load or rated load.
Safety net
A safety net that is located and supported in such a way that it arrests the fall of a worker who may fall into it without endangering the worker.
Screen
An apparatus with circular apertures or mesh for separating sizes of granular material, e.g. aggregates.
Scupper
An outlet in the wall of a building or a parapet wall for drainage of overflow water from a floor or roof directly to the outside. Special scupper drains connected to internal drains are sometimes installed at roof and wall junctions.
Sealant
A mixture of polymers, fillers, and pigments used to fill and seal joints where moderate movement is expected; unlike caulking, it cures to a resilient solid. See also caulking.
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.
Self-adhesive 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.
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.
Sheet
An unrolled piece of roofing felt or other single-ply prefabricated material.
Shingle
1. A small unit of prepared roofing designed for installation with similar units in overlapping rows on inclines.
2. To cover with shingles. 3. To apply any sheet material in overlapping rows like shingles.
Shingling
1. The application of any roofing material by overlapping the units in horizontal courses with the overlapping down the slope to shed water.
2. The usual method of laying roofing felts in built-up roofing with overlapping sufficient to produce the number of plies desired.
Single ply membranes
Roofing membranes that are field applied using just one layer of membrane material (either homogeneous or composite) rather than multiple layers.
Single ply roofing
A roofing system in which the principal roof covering is a single layer flexible membrane often thermoset or thermoplastic membrane.
Slag
A gray porous aggregate produced by air cooling and crushing residue from blast furnaces, used as a protective surfacing for shingles, roll roofing and built-up roofing. Also called blast-furnace slag. See also granules.
Slope
The incline of a roof surface in degrees, as a slope ratio of fall to run, or as a percentage of fall to run. See incline.
Split
A membrane tear resulting from tensile stress.
Spudder
See scraper.
Stabilizer
1. Water insoluble mineral matter passing a 212um (NO.70) sieve used in a mixture with solid or semi-solid bituminous materials.
2. Various heat and light stabilizers are included in the formulation of PVC for roofing. See also filler.
Stack
A vertical vent pipe penetrating above a roof such as that used to provide an escape for foul gases from plumbing fixtures.
Starter 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 course.
Starter strip
A strip of felt applied at the eaves or other starting line of built-up roofing to serve as the base for the first full course of roofing.
Strainer
A wire, plastic or cast-metal cage placed over the top of a roof drain to prevent debris and leaves on the roof from entering the drain.
Stress
The force acting across a unit area in solid material in resisting the separation, compressing or sliding that tends to be induced by external forces. Also, the ratio of applied load to the initial cross-sectional area, or the maximum stress in the outer fibres due to an applied flexural load.
Strip shingles
Asphalt shingles that are manufactured in strips, approximately three times as long as they are wide.
Styrene Butadiene Styrene (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 asphalt.
Substrate
The surface upon which the roofing or waterproofing membrane is placed. It may be structural deck or insulation or any other base material.
Sump
A depression around a drain in the roof deck or insulation to provide a water reservoir.
Surfacing
Any aggregate or granular material or coating used as a protective covering on the weather surface of roofing. The protective and traffic-bearing layer of a roof terrace is also called the top cover.
Tab
The exposed portion of strip shingles defined by cutouts.
Tanker
A tank truck specially designed with heating and pumping equipment for conveying and dispensing liquid bitumen.
Tar
Black or dark brown liquid or semi-liquid condensates derived from the heating or baking, sometimes called destructive distillation, of wood, peat, oil shale, bone, petroleum, coal or other organic materials. The word is incorrectly used to describe asphalt as in the expression "tar-and-gravel roofing."
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.
Thermoset
Unaffected by heat. It is often called elastomer or synthetic rubber. The inertness imparts elasticity and weather resistance.
Torch applied
Method used in the installation of polymer modified bitumen membranes characterized by using open flame propane torch equipment.
Truss
A combination of members such as beams, bars and ties, usually arranged in triangular units, to form a rigid framework for supporting loads over relatively long spans as in wide span roof construction.
Ultraviolet (UV)
Invisible light radiation, adjacent to the violent end of the visible spectrum, with wavelengths from about 200 to 400 nanometres.
Underlayment
See sheathing paper.
Valley
The horizontal line formed along the depressed angle at the bottom of two inclined roof surfaces.
Vapour retarder
Material used to retard the passage of vapour or moisture into the roof system where harmful condensation of vapour within the system could take place.
Vegetated roof
A roof membrane system with a top layer of living plants in an engineered soil blend (growth medium). Green roof systems are also referred to as vegetated roof covers, roof gardens, eco-roofs, or landscaped roofs.
Vent
An opening designed to convey water vapour or other gas from inside a building or a building component to the atmosphere, thereby relieving vapour pressure.
Vermiculite
An aggregate used for lightweight insulating concrete and roof fills, formed by the expansion of mica rock through heating.
Viscosity
The internal resistance offered by a fluid to change shape or to relative motion or flow of its parts. The flow characteristics of bitumen is measured in centistokes. Asphalt may vary from 30 to 500 centistokes when heated from 175°C to 260°C depending on the asphalt type.
Vulcanization
An irreversible process during which a rubber compound, through a change in its chemical structure, e.g. 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. See also cross linking.
Waterproof
The quality of a membrane, membrane material or other component to prevent water entry.
Waterproofing
1. A material used to treat or cover a building element or component to prevent leakage of water.
2. Treatment of a surface or structure to prevent the passage of water under hydrostatic pressure.
Water shedding
The ability of individual, overlapping components to resist the passage of water without hydrostatic pressure.
Weatherproof
The ability of a membrane or roof covering to prevent the passage of water with a limited amount of hydrostatic pressure.
Winch
A hoist used for hauling or hoisting materials to the top of a roof.
Wind uplift
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 surface.
Wrinkles
Small ripples formed at the surface of roofing membranes similar to ridging.