Architectural and Engineering Glossary

Unsound Wood

Same as decayed wood.

Unstable Equilibrium

The condition of astructure in a state of equilibrium;when a slight disturbance is applied to the structure and then removed,the structure does not return to its original equilibrium position.Compare with stable equilibrium.

Unstable Soil

Earth material that,because of its nature or the influence of related conditions,cannot be depended upon to remain in place without extra support,such as would be furnished by a system of shoring.

Unstiffened Member

A member (or part of a member) which is subjected to compressive forces and is not reinforced in a direction perpendicular to the direction along which it will bend most easily.

Unsupported Length

The distance between the end supports of a beam.

Unwrought Timber

Sawn lumber that has not been planed.

Unwrought Timber, Unwrot Timber

British term for undressed lumber.

Up Stairs

Stairs designated to be used for going up only,as in some schools and institutional buildings.

Up-and-down Sash

An archaic term for a rectangular window sash that moves in a vertical plane;a double hung window.

Up-and-over Door

An overhead door which is a single leaf.


Abbr. for “Uniform Plumbing Code.”

Upfeed System

A water distribution system in which water is supplied and fed upward through the vertical piping to the highest  point  of the system that may be fed,using the available pressure.


The upward push of a soil mass.


1.The upward pressure on a structure due to the pressure of the water below.2.The pressure acting on a material that tends to lift it off its supports or fasteners as a result of an external force (for example,wind) acting on it.

Uplift Capacity

A measure of the resistance of a pile to being pulled out of the ground.

Upper Capital

Same as dosseret.

Upping Block

Same as horse block.


1.A vertical piece of timber or stone.2.A vertical structural member.


1.To shorten and thicken by hammering,as a bar of heated metal struck on the end.2.In the region of a weld,a localized increase in volume resulting from the application of pressure.3.A defect in timber due to a severe blow that breaks the fibers across the grain.

Upset Price

See guaranteed maximum cost.

Upset Welding

A resistance welding process in which the joining of two surfaces is effected by the heat obtained from the flow of current through the resistance provided by the area of contact between the surfaces to be joined;pressure is employed in this process.


The hot forging operation by which the cross sectional area of a metal bar or rod is increased locally.

Upside-down Roof

Same as inverted roof.


The back part of a stage,away from the audience.


The portion of a house or small building situated on the floors above the main or entrance floor.


The part of a roof covering that turns up against a vertical surface.

Upstanding Beam

In a concrete floor,a beam which projects above a concrete slab rather than below it.


A change in the zoning classification of a property from one of lower use to one that is of higher use;for example,a change from residential to commercial use.


On drawings,abbr.for urinal.

Urban Area

An area which is within the city limits,or closely linked to it by common use of public utilities or services.

Urban Planning

See city planning and community planning.

Urban Renewal

The improvement of slum,deteriorated,and underutilized areas of a city;generally implies improvement realized through city,state,and,particularly,federal programs,including the clearance and redevelopment of slums,the rehabilitation of relatively sound structures, and conservation measures to arrest the spread of deterioration.

Urban Sprawl

An unplanned development of open land,usually on the outskirts of a city.

Urea Resin Adhesive

A dry powder which is mixed with water before being applied;has high early strength and good resistance to heat;not recommended for poorly fitted joints or outdoor use.


Same as urea resin adhesive.


Same as volute.


A sanitary fixture equipped with a water supply and drain for flushing away urine.

US Customary Units

The system of units ordinarily used in the US,for example,the unit of length may be the inch,foot,yard,or mile.

Usable Floor Area

The net floor area in a building after deducting the area occupied by lobbies,corridors,rest rooms,cafeterias, etc.

Usable Life

See pot life.


Abbr. for American National Standards Institute.

Use District

An area,designated in the zoning ordinance of a municipality,within which specified types of land use are permitted and others forbidden.


On drawings,abbr.for “United States gauge.”


See public utility.

Utility Pole

An outdoor pole installed by a telephone or electric utility company for the support of conductors and other electric or telephone equipment.

Utility Sheet

Mill finished metal sheeting;available in a variety of sizes suitable for general building construction.

Utility Tractor

A low to medium horsepower tractor;used primarily for pulling auxiliary equipment,but also used in construction with attachments for trenching,dozing,breaking,etc.

Utility Vent

A vent,1 which rises well above the highest water level of a fixture and then turns downward before it connects to the main vent or stack vent.

Utility Window

A low cost hot rolled steel window for use in basement areaways,garages,shops,and the like;usually has a hopper light over a fixed light.

Utilization Equipment

Any equipment which utilizes electric energy for mechanical,heating,lighting,or similar useful purposes.