U-value
The amount of heat a door or window conducts between the inside air and the environment.

U.S. Department of Housing and Urban Development
Also known as HUD.   This federal agency oversees the Federal Housing Administration and a variety of housing and community development programs.

Underlayment
A layer of wood between the sub-floor and the floor.

Underwriters' knot
A code-approved knot tied at the end of an electrical cord to prevent the wires from being pulled away from their connection to electrical terminals.

Underwriting
The process in which lenders evaluate the risks posed by a particular borrower and set appropriate conditions for the loan.

Underwriting fee
A fee charged by mortgage lenders to verify information on the loan application and make a final decision about whether or not to approve the loan.

Undisclosed heir
A person who claims the right to a piece of property after the death of an owner without a will.

Undisclosed spouse
A marital partner who can claim the right to a piece of property but is not identified in the owner's will.

Unilateral contract
A one-sided contract.  If one party makes a promise to do something, the second party is not legally required to perform.  If the second party does comply, however, the first party is obligated to keep its promise.

Unrecorded deed
A deed that transfers ownership from one party to another without being officially recorded.

Unsecured loan
Any loan that is not backed by collateral.

Upgrades
Options offered to buyers in a new-home project that go beyond the standard carpeting, lighting, finish carpentry, and other amenities.

Upzoning
The process in which a property is zoned from a lower to a higher use.

Urban sprawl
The unplanned expansion of development over a large area.

Usury
Illegally excessive interest charged on any loan.