| Glossary |
U-Value: A measure of air-to-heat transmission (loss or gain) due to the thermal conductance and the difference in indoor and outdoor temperatures. As the U-value decreases, so does the amount of heat that is transferred through the glazing material. The lower the U-value, the more restrictive the fenestration product is to heat transfer. Reciprocal of R-value.
U.L. (Underwriters Laboratories): A private research firm located in the United States that attempts to classify and determine the safety of various materials and products.
Ultraviolet: The invisible rays of the spectrum of light which are at its violet end. Sometimes abbreviated U.V.
Ultraviolet Degradation: A reduction in certain performance limits caused by exposure to ultraviolet light.
Undercoat: A coating applied prior to the finishing or top coats of a paint job. It may be the first of two of three coats. In some usage of the word it may become synonymous with priming coat.
Undercounter: A style of lavatory which is positioned under the cutout of the countertop.
Underground Plumbing: The plumbing drain and waste lines that are installed beneath a basement floor.
Underlayment: A material placed under finish coverings, such as flooring, or shingles, to provide a smooth, even surface for applying the finish.
Union: A plumbing fitting that joins pipes end-to-end so they can be dismantled.
Union Nut: A fitting that joins two sections of pipe.
Uprights: Vertical members supporting the sides of a trench.
Utility Easement: The area of the earth that has electric, gas, or telephone lines. These areas may be owned by the homeowner, but the utility company has the legal right to enter the area as necessary to repair or service the lines.
UV Rays: Ultraviolet rays from the sun.
