This glossary contains many useful terms and definitions that will help you understand much of the work we do at ROOFCORP.

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Warm roof assembly: a roof assembly configured with each component placed immediately on top of the preceding component; each component is in contact with the adjacent component. No space is provided for ventilation of the roof assembly. Also known as a “compact” roof assembly.

Wash coat: a primer, typically provided on the back side of painted metal products to help protect the underlying metal from wear and corrosion.

Water cure: a method of curing a material, such as concrete, by applying a fine mist of water over the surface to control the rate of moisture evaporation from the material. Water cutoff: see Cutoff.

Water-shedding: the ability of individual, overlapping components to resist the passage of water without hydrostatic pressure.

Water stop: a diaphragm used across a joint as a sealant, usually to prevent the passage of water. Water table: the level within the ground, below which the soil is saturated with water.

Water vapor transmission: a measure of the rate of transmission of water vapor through a material under controlled laboratory conditions of temperature and humidity. Customary units are grains/h·ft2.

Waterproof: the quality of a membrane, membrane material, or other component to prevent water entry.

Waterproofing: treatment of a surface or structure to prevent the passage of water under hydrostatic pressure.

Wear course: the top layer of surfacing that carries pedestrian or vehicular traffic. Sometimes referred to as wearing surface.

Wearing surface: see Wear course. Weatherproof: the ability of a membrane or roof covering to prevent the passage of water with a limited amount of hydrostatic pressure.

Weep holes: small openings whose purpose is to permit drainage of water that accumulates inside a building component (e.g., a brick wall, skylight frame, etc.).

Weld: to join pieces of metal together by heat fusion. Wet: a condition where free water is present in a substance.

Wet bulb temperature: the temperature of air as registered by a thermometer whose bulb is covered by a water wetted wick.

Wet film thickness: the thickness, expressed in mils, of a coating or mastic as applied but not cured. For comparison, see Dry film thickness.

Wicking: the process of moisture movement by capillary action.

Wind clip: a steep-slope roofing attachment device that fits over the butt end of tile, slate and stone to help secure individual roofing units from wind uplift.

Wind load: force exerted by the wind on a structure or part of a structure.

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.

Wire tie system: a system of attachment for steep-slope roofing units (e.g., tile, slate and stone) using fasteners (nails and/or screws) in conjunction with wire to provide a concealed fastening system. Work slab: see Mud slab.

Woven valley: a method of valley construction in which shingles or roofing from both sides of the valley extend across the valley and are woven together by overlapping alternate courses as they are applied.

Wythe: a masonry wall, one masonry unit, a minimum of two inches thick.

Yield: in SPF-based roofing, the volume of foam per unit weight, normally expressed as board feet per pound or board feet per 1000 pounds.

Z section: a member formed in the shape of a “Z” from coiled steel stock.

Zinc: a hard bluish white metal, brittle at normal temperatures, very malleable and ductile when heated; not subject to corrosion; used for galvanizing sheet steel and iron, in various metal alloys, and as an oxide for white paint pigment.