====== Roofing Glossary: U to X ======


===== U =====


==== Underlayment ====
  * 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.


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



===== V =====


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


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


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



===== W =====


==== Warranty ====
  * 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.


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


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




===== X =====