UBC—Uniform Building Code (See ICBO)

Ultimate elongation—The elongation of a stretched specimen at the time of break. Usually reported as percent of the original length. Also called breaking strain.

Unsupported sheeting—A polymer sheeting one or more plies thick without a reinforcing fabric layer or scrim.

Uplift—Wind load on a building which causes a load in the upward direction. (See Suction)