U
UL (Underwriters' Laboratories)- An independent
testing agency that checks electrical devices and other
components for possible safety hazards.
Undercoat- A coating applied prior to the finishing or top coats
of a paint job. It may be the first of two or the second
of three coats. Sometimes called the Prime coat.
Underground
plumbing- The plumbing drain and waste lines
that are installed beneath a basement floor.
Underlayment- A ¼" material placed over the subfloor plywood
sheeting and under finish coverings, such as vinyl flooring,
to provide a smooth, even surface. Also a secondary
roofing layer that is waterproof or water-resistant,
installed on the roof deck and beneath shingles or other
roof-finishing layer.
Union- A plumbing fitting that joins pipes end-to-end so they
can be dismantled.
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.