Search Results for U U-value (thermal transmittance) The time rate of heat flow per unit area between fluids on the warm side and cold side of a barrier, calculated in accordance with the difference in unit temperature between the two test fluids. UBC Uniform Building Code UL Label A seal of certification attached by Underwritersí Laboratories, Inc. to building materials, electrical wiring and components, storage vessels, and other devices, attesting that the item has been rated according to performance tests on such products. ultimate load The load at which a unit or structure fails. ultimate strength The maximum resistance to load that a member or structure is capable of developing before failure occurs. unbraced frame A structural frame, resistant to the lateral load carried, due to the ability of its members and connections to withstand bending and shear stresses without additional diagonal bracing, K-bracing, or other extra supporting devices. unbraced length The greatest length between points on a compression member not restrained against lateral movement by beams, slabs, or bracing. undercoat A coat of paint that improves the seal of wood or of a previous coat of paint, and provides a superior adhesive base for the top coat. undercut door A door with greater than normal clearance at the floor to give more ventilation to an area. underdrain A drain installed in porous fill under a slab to drain off ground water. underlayment Structural wood panels designed to be used under finished flooring to provide a smooth surface for the finish material. underpinning The construction of new substructure support beneath a column or a wall, without removing the superstructure, in order to increase the load capacity or return it to its former design limits. Underwritersí Laboratories, Inc. (UL) A private, nonprofit organization that tests, inspects, classifies, and rates devices and components to ensure that manufacturers comply with various UL standards. uniform load A load distributed uniformly over a structure or a portion of a structure. unit heater A factory-assembled heating unit consisting of a housing, a heating element, a fan and motor, and a directional outlet. unsupported wall height Masonry wall construction limit for wall height set by local codes determined by ratio of wall thickness to height of wall. utility A grade of softwood lumber used when a combination of strength and economy is desired. Utility grade is suitable for many uses in construction, but lacks the strength of Standard, the next highest grade in light framing, and is not allowed in some applications. Search Again