W | Roofing Glossary

Roofing Glossary, a collection of terms used in the roofing industry

There are 639 entries in this glossary.

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Term	Definition
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.
Warm Wall	the finished wall inside of a structure, used in roofing to determine how far up the deck to install waterproof underlayments at eaves. Warranty: the written promise to the owner of roofing materials for roofing related problems.
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 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.
Water-shedding	the ability of individual, overlapping components to resist the passage of water without hydrostatic pressure.
Waterproof	the quality of a membrane, membrane material, or other component to prevent water entry. "Water resistant" and "waterproof" often refer to penetration of liquid water.
Waterproofing	treatment of a surface or structure to prevent the passage of water under hydrostatic pressure. Waterproofing is used in reference to building structures.
Waterproofing Underlayments	Modified bitumen based roofing underlayments. Designed to seal to wood decks and waterproof critical leak areas. Wear course: the top layer of surfacing that carries pedestrian or vehicular traffic. Sometimes referred to as wearing surface.
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. The ability of liquid to flow against gravity where liquid spontaneously rises in a narrow space such as a thin tube, or in porous materials such as paper or in some non-porous materials such as liquified carbon fibre.
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. The NRCA Roofing and Waterproofing Manual—Fifth Edition Glossary 1009
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.
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.