Roofing Glossary: U to X

an asphalt-saturated felt or other sheet material (may be self-adhering) installed between the roof deck and roof covering, usually used in a steep-slope roof construction. Underlayment is primarily used to separate the roof covering from the roof deck, shed water and provide secondary weather protection for the roof area of the building.

Wind load on a building which causes a load in the upward direction.

the internal angle formed by the intersection of two sloping roof planes.

an opening designed to convey air, heat, water vapor or gas from inside a building or a building component to the atmosphere.

An accessory usually used on the roof that allows air to pass through.

A warranty is furnished to the owner, generally by the manufacturer of the roofing materials, against manufacturing defects, to maintain a specified roof in a watertight condition for a specified time. Terms and conditions of individual warranties vary from manufacturer to manufacturer.

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

The process of moisture movement by capillary action as contrasted to movement of water vapor.