Vapor migration: the movement of water vapor from a region of high vapor pressure to a region of lower vapor pressure.
Vent: an opening designed to convey air, heat, water vapor or gas from inside a building or a building component to the atmosphere.
Viscosity: the resistance of a material to flow under stress. For bitumen, measured in centipoises. See Viscous.
Viscous: resistant to flow under stress.
Void: an open space or break in consistency.
Volatile organic compounds (VOC): mean any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic aced, metallic carbides or carbonates, and ammonium carbonate, which participate in atmospheric photochemical reactions.