Architectural and Engineering Glossary

Unfired Brick

A solid masonry unit that has not been fired in a kiln at a high temperature. 

Unframed Door

A door not in a frame,as a batten door.

Ungauged Lime Plaster

Plaster containing no gypsum;usually composed of lime,sand,and water.

Unglazed Tile

A hard,dense ceramic tile for floors or walls;of homogeneous composition throughout,deriving its color and texture from the materials of which the body is made and from the method of manufacture.

Unidirectional Microphone

A microphone whose response is predominantly from a single direction.

Uniform Building Code (UBC)

1.A US national building code,prepared and issued by the International Conference of Building Code Officials,5360 South Workman Mill Road,Whittier,CA 90601-2294.Also see BOCA National Building Code.2.Any model code,similar to 1,of a country other than the US.

Uniform Construction Index

An outline of building trades and products,separated into 16 divisions (illustrated under contract documents),that are arranged by trade and construction sequence.

Uniform Federal Accessibility Standards (UFAS)

A set of standards concerning accessibility for the disabled,which are available at no charge from:US Access Board,1331 F Street NW, Suite 1000,Washington,DC 20004-1111.Also see Americans with Disabilities Act.

Uniform Grading

A particle size distribution of aggregate in which all pan fractions are present without a preponderance of any one size or group of sizes.

Uniform Load

A load,1 uniformly distributed over all or a portion of a structure.

Uniform Settlement

The sinking into the ground of various parts of a building at the same rate.

Uniform System

Coordination of specification sections,filing of technical data and product literature,and construction cost accounting, organized in 16 divisions based on an interrelationship of place,trade,function,or material.

Uniformity Coefficient

A coefficient related to the size distribution of a granular material,such as sand;obtained by dividing one size of grain (60% of the grains are smaller than this size,by weight) by a second size (10% of the grains are smaller than this size,by weight).

Uninterruptible Power System

An electric power system which provides continuity of power,to the apparatus or appliances being served,without discernible interruption upon failure of the normal power supply.


A pipe fitting,1 used to connect the ends of two pipes,neither of which can be turned; consists of three pieces,the two end pieces (having inner threads),which are tightened around the pipe ends to be joined,and a center piece,which draws the two end pieces together as it is rotated,effecting a seal.Also see flange union.

Union Bend

See union elbow.

Union Clip

A fitting for interconnecting the ends of two rainwater gutters.

Union Elbow

A pipe elbow,1 having a union type coupling on one end,so that the coupling end may be connected to the end of a pipe with out turning the pipe.

Union Fitting

A union elbow or a union tee. 

Union Joint

A pipe joint made with a union. 

Union Tee

A pipe tee having a union type coupling on one end.

Union Vent

Same as dual vent.

Unit Absorber

A sound absorptive element which is designed for application on a wall or ceiling as a single unit;usually part of a spaced array of similar units.

Unit Air Conditioner

Same as room air conditioner.

Unit Construction

Same as modular construction.

Unit Cooler

See room air conditioner.

Unit Lock

A preassembled lock.

Unit Masonry

See masonry unit.

Unit Price

An amount stated in a contract as the price per unit of measurement for materials or services as described in the contract documents.

Unit Stress

The value obtained by dividing the total stress by the cross sectional area that is stressed.

Unit Substation

One or more transformers which are mechanically or electrically connected to (and coordinated in design with) one or more switchgear or motor control assemblies,or combinations thereof.

Unit System

A curtain wall,1 composed entirely of prefabricated units attached to the building structure.

Unit Vent

See dual vent.

Unit Ventilator

An operable air inlet damper which furnishes outdoor air to an interior space;may be provided with a filter and heating and/or cooling coils.

Unit Water Content

1.The quantity of water per unit volume of freshly mixed concrete.2.The quantity of water on which the water cement ratio is based,not including water absorbed by the aggregate.

Unit-type Vent

An opening of relatively small area (one of a number which are distributed about a roof according to the occupancy requirements),usually having a lightweight metal frame and housing,with hinged dampers which may be operated manually or which open          automatically in the event of fire.

Unitary Air Conditioner

Equipment consisting of one or more factory fabricated assemblies designed to perform the functions of air moving,air cleaning,cooling,and dehumidification;the assemblies usually include a fan,evaporator or cooling coil,and a compressor and condenser in combination;a heating unit also may be included.

United Inches

The sum of the length and width (expressed in inches) of a rectangular piece of glass.

United States Of America Standards Institute

See American National Standards Institute.


Descriptive of a door lock,a door closer,or the like,which can be used on either a right hand swing door or a left hand swing door. 

Universal Motor

A motor capable of operating either on alternating current or on direct current. 


A control mechanism for an electric motor driven compressor;controls the pressure head of the compressor;permits the motor to be started at low starting torque by removing theload during this initial period of operation.

Unprotected Corner

Of a slab,a corner having no adequate provisions for transfer of load,so that the corner must carry over 80% of the load. 

Unprotected Metal Construction

Steel frame construction in which the framing members are not fireproofed.

Unreinforced Concrete

See plain concrete.

Unrestrained Member

A member that is permitted to rotate freely at its points of support.

Unseasoned Lumber

Same as green lumber.


Descriptive of a plaster,slaked lime,cement,or other mortar which contains particles that may expand.

Unsound Knot, Decayed Knot, Rotten Knot

 A knot that is softer than the surrounding wood. 

Unsound Plaster

Hydrated lime,plaster,or mortar which contains unhydrated particles thatmay expand and cause popping or pitting.