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Cant:

(1) Short for Cant Strip; (2) The act of installing foam at a right angle adjunct.

 

Cant Strip:

A triangular-shaped strip of material used to ease the transition from a horizontal plane to a vertical plane. Cant strips can be made of wood, wood fiber, perlite, or other materials.

 

Cap Flashing:

A material used to cover the top edge of base flashings or other flashings. See also Coping.

 

Cap Sheet:

A granule-surfaced membrane often used as the top ply of BUR or modified roof systems.

 

Caulking:

The act of sealing a joint or of material.

 

Channel Flashing:

Flashing with a built-in channel for runoff; used where roof planes intersect other vertical planes.

 

Closed-Cut Valley:

A method of valley application in which shingles from one side of the valley extend across the valley while shingles from the other side are installed over the top of those and then trimmed back approximately 2 inches from the valley centerline.

 

Coal Tar Pitch:

A type of coal tar used in dead-level or low-slope built-up roofs. It is not for use in roofs exceeding ¼" in 12" (2%) slope.

 

Coal Tar Roof Cement:

A trowelable mixture of processed coal tar base, solvents, mineral fillers and/or fibers.

 

Coated Base Sheet:

An asphalt-saturated base sheet membrane later coated with harder, more viscous asphalt, thereby increasing its impermeability to moisture.

 

Coated Felt:

 

An asphalt-saturated ply sheet that has also been coated on both sides with harder, more viscous asphalt.

 

Composition Shingle:

A type of shingle used in steep-slope roofing and generally comprised of weathering-grade asphalt, a fiber glass reinforcing mat, an adhesive strip, and mineral granules.

 

Coping:

The piece of material used to cover the top of a wall and protect it from the elements. It can be constructed from metal, masonry, or stone.

 

Curb:

(1) A raised member used to support skylights, HVAC units, exhaust fans, hatches or other pieces of mechanical equipment above the level of the roof surface, should be a minimum of eight inches (8") in height; (2) A raised roof perimeter that is relatively low in height.

 

Cut-off:

A detail designed to seal and prevent lateral water movement in an insulation system, and used to separate different sections of a roofing system.

Cutout:

The open area between shingle tabs. Also known as a "throat".

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Insulation:

Material used to help maintain a certain temperature in a building by reducing the flow of heat to and from that building. See also Thermal Insulation.

 

Intake Ventilation:

The part of a ventilation system used to draw fresh air in. Usually vents installed in the soffit or along the eaves of a building.

 

Interlayment:

A waterproof material usually installed between adjacent rows of wood shakes to help with the roof’s waterproofing characteristics.

 

Interlocking Shingles:

Shingles that lock together to provide wind resistance.

 

Inverted Roof Membrane Assembly (IRMA®):

A variation of the "Protected Membrane Roof Assembly" in which Styrofoam® brand insulation is used. IRMA® and Styrofoam® are registered trademarks of the Dow Chemical Company.

 

Isocyanate:

A highly reactive organic chemical containing one or more Isocyanate groups. A basic component in Sprayed Polyurethane Foam systems and some polyurethane coating systems.

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Joint Tape:

Tape used to seal joints between insulation boards.

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Pan:

(1) The concave piece of "Pan and Cover" tile whose rounded surface touches the top side of the roof substrate.

 

(2) The flat part of a roofing panel located between the ribs.

 

Pan Flashing:

A sheet metal flashing that covers an equipment platform and is designed to counter flash the base flashings surrounding the platform.

 

Pass:

The term used to describe the application of one layer of Spray Polyurethane Foam (SPF). The speed of a pass will determine foam thickness.

 

Pass Line:

The distinct line formed between two passes of SPF. This line is the top skin of the bottom pass of the SPF.

 

Penetration:

Any object that pierces the surface of the roof.

 

Permeability:

The rate of flow of a liquid or gas through a porous material.

 

Phasing:

Installing roof system components in separate time intervals. For instance, installing a base sheet, and then two plies of roofing one day, and coming back and installing the remaining two plies one or more days later. It is generally not considered Phasing if the surfacing is applied at a later date.

 

Pipe Boot:

A prefabricated flashing piece used to flash around circular pipe penetrations. Also known as a Roof Jack.

 

Pitch:

Term used to describe Roof Slope and also short for Coal Tar Pitch.

 

Pitch Pocket (A.K.A. Pitch Pan):

A flanged piece of flashing material placed around irregularly shaped roof penetrations and filled with grout and a pourable sealer to seal around the penetration in order to seal it against moisture entry. Pitch pockets are a good source of leaks and should be avoided if possible.

 

Ply:

A layer of felt or other reinforcement material in a roof system.

 

Polymer:

Any of numerous natural and synthetic compounds of usually high molecular weight consisting of up to millions of repeated linked units, each a relatively light and simple molecule.

 

Polymer Modified Bitumen:

See Modified Bitumen.

 

Ponding:

The accumulation of water at low-lying areas on a roof.

 

Pop Rivet:

A small metal pin having a head on one end, inserted through aligned holes in pieces of light gauge metal to be joined and then the head is expanded to join the metal.

 

Pourable Sealer:

A type of sealant that is initially in liquid form commonly used in conjunction with pitch pans to form a water-tight barrier around penetrations that are difficult to flash.

 

Primer:

A material that is applied to a surface in order to increase that surface’s ability to adhere to or work in conjunction with a subsequently applied material.

 

Protected Membrane Roof (PMR):

A roof assembly in which the insulation and ballast are placed on top of the membrane component. Commonly referred to as an "inverted roof assembly."

 

Puncture Resistance:

The ability of a material to withstand being pierced by a sharp object.

 

PVC:

Polyvinyl Chloride.

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Tab:

The portion of an asphalt shingle that is outlined by the cutouts.

 

Tapered Edge Strip:

Tapered insulation strip used to ease transitions from one substrate elevation to another and to provide slope along roof perimeters.

 

Tape:

See Joint Tape

 

Tar:

A brown or black bituminous material, liquid or semi-solid in consistency.

 

Tar Boil:

A small bubble found in the flood coat of an aggregate-surfaced built-up roof; usually the result of trapped moisture vapor. Tar Boils are also known as blueberries or blackberries.

 

Tear-Off:

To remove a roof system down to the structural substrate.

 

Tear Strength:

The strength necessary to tear a material.

 

Tensile Strength:

The amount of longitudinal pulling stress that a material can withstand before being pulled apart.

 

Termination:

The sealed edges of a roof membrane.

 

Termination Bar:

A bar, usually metal or vinyl, used to seal and anchor the free edges of a roof membrane.

 

Terne:

Sheet iron or steel plated with an alloy of three or four parts of lead to one part of tin, used as a roofing material.

 

Terra Cotta:

A semifired ceramic clay used in building construction.

 

Thatch Roof:

A roof covering made with straw, palms, reeds or other natural growths that are bound together in order to shed water.

 

Thermal Barrier:

Material used in conjunction with polyurethane foam that is designed to inhibit the rise in temperature of the foam during a fire in order to delay the foam’s involvement in the fire. Time ratings for thermal barriers should exceed 15 minutes.

 

Thermal Insulation:

A material used to reduce heat flow.

 

Thermal Movement:

Movement of a material resulting from temperature changes.

 

Thermal Resistance (R):

The measure of a material’s ability to resist heat flow. The formula for Thermal Resistance is R = L / k where (L) is the material’s thickness and (k) is the material’s Thermal Conductivity constant. The higher a material’s R-value, the better it insulates, and conversely.

 

Thermal Shock:

The damage to a roof resulting from expansion and contraction which are the result of sudden extreme temperature changes. Thermal Shock often occurs when a cold rain shower suddenly cools a roof during a hot day.

 

Thermoplastic:

(1)Becoming soft when heated and hard when cooled.

 

(2)A thermoplastic resin, such as polystyrene or polyethylene.

 

Thermoset:

A material that cannot be reshaped or formed by heating. EPDM and Butyl are thermosets.

 

Throat:

(1) The cutout of a shingle.

 

(2) The narrowing passage located between a fireplace and smoke chamber or flue.

 

Tie-In:

The joining of two different roof systems.

 

Tie-Off:

A watertight seal used to terminate roof membranes at system adjuncts, terminations, flashings, or substrates. Can be temporary or permanent.

 

Toggle Bolt:

A bolt with a separate toggle end that can be flattened to fit through a pre-drilled hole and that springs outward to provide securement when the bolt is tightened.

 

Tongue and Groove:

Premanufactured materials with a convex "tongue" on one side and a concave "groove" on the other so that pieces of material can be joined together by placing the tongue of one piece into the groove of an adjacent piece so that the pieces fit more securely together.

 

Torque:

Force applied to an object, particularly, to screw a mechanical fastener into a roof deck or substrate.

 

TPA:

Tri-Polymer Alloy.

 

Traffic:

Any rooftop activity that can potentially damage the roof surface.

 

Transverse Seam:

The joint between the top of one metal roof panel and the bottom of the next panel, which runs perpendicular to the roof slope.

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Underlayment:

A material installed over the roof deck prior to the application of the primary roof covering. Usually consists of fifteen (15#) or thirty (30#) pound organic felt but can also be self-adhering such as an ice and water protection membrane.

 

Uplift:

See Wind Uplift.

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Valley:

The internal intersection of two sloping roof planes that runs from the eaves to the ridge. This intersection collects the most water run-off. See Open Valley, Closed-Cut Valley and, Woven Valley

 

Vapor Migration:

The natural movement of water vapor from regions of higher vapor pressure to regions of lower vapor pressure.

 

 

Vapor Pressure:

The pressure at which a liquid and its vapor are in equilibrium at a definite temperature.

 

Vapor Retarder:

A material used to restrict the passage of water vapor through a roof assembly.

 

Veneer:

Any of the thin layers of wood glued together to make plywood.

 

Vent:

An opening or device used to permit air or vapors to exit an enclosed structure.

 

Ventilation Short Circuit:

The disruption of air flow in an intake-exhaust ventilation system. For instance, if vents such as turbine vents or gable vents are placed in between the intake vents and exhaust vents (such as soffit and ridge vents) then the draw created by the Stack Effect will be disrupted and the ventilation system will be much less effective.

 

Ventilator:

A device that circulates fresh air and expels stale air.

 

Verge of Popcorn Texture:

A rough surface texture of Sprayed Polyurethane Foam generally considered unsuitable to receive a base coating. Nodules on this surface are larger than the valleys and an additional 50% or more of coating material is necessary to properly cover and protect the surface.

 

Viscosity:

The resistance of a material to heat flow.

 

Viscous:

Having a fairly high resistance to heat flow.

 

Void:

An open space or a break in continuity; a gap.

 

Volatile:

That which readily vaporizes; evaporates quickly.

 

Vulcanize:

To improve the strength, resiliency, and freedom from stickiness and odor of rubber, for example, by combining with sulfur or other additives in the presence of heat and pressure

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Water Absorption:

The increase in weight of a test specimen expressed as a percentage of its dry weight after being immersed in water for a specified time at a given temperature.

 

Water Guard:

A turned up edge on valley metal or continuous wall flashing; used to prevent water migration under the roof system.

 

Water Stop:

Material placed over a joint and used to prevent water entry.

 

Waterproof:

Being resistant to moisture infiltration.

 

Waterproofing:

The treatment of a surface or structure in order to prevent the passage of water under hydrostatic pressure.

 

Weather:

To undergo degradation in quality and appearance which is caused by exposure to the sun, wind, rain, etc.

 

Wind Clip:

A clip that slips over the ends of tile, slate and other steep slope roofing materials in order to help prevent wind uplift damage.

 

Wind Uplift:

(1) The upward displacement of a section of a roof system or component caused by movement of air from a location of higher air pressure, such as inside a building, to an area of lower air pressure, such as the surface of a roof during a windy day. Strong wind across the surface of a roof, especially at corners and along perimeters, creates low air pressure above the surface of the roof. Nature will automatically try to compensate for this by moving air from an area of higher pressure such as inside a building. If all penetrations and perimeters are not properly sealed, then "blow-off" can occur.

 

 

(2) Displacement or blow-off of shingles or other roofing caused by the wind.

 

Windward:

Facing into the wind..

 

Woven Valley

A valley construction whereby the valley has a woven look which is effected by overlapping alternate courses of shingles from both sides of the valley.

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Z Bar or Z Section:

A piece of steel formed in the shape of a "Z."

 

Zinc

A bluish-white, lustrous metallic element that is brittle at room temperature but malleable with heating. It is used to form a wide variety of alloys including brass, bronze, various solders, and nickel silver, in galvanizing iron and other metals, for electric fuses, anodes, and meter cases, and in roofing, gutters, flashings, edge metals and also for various household objects.

 

 

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