Architectural and Engineering Glossary



The sapwood cut from the edge of a board.


Pertaining to stone.


A white pigment consisting of zinc sulfide and barium sulfate,having moderate hiding power;high-strength lithopone contains a higher percentage of zinc sulfide.

Lithostrotum Opus

In ancient Greece and Rome,an ornamental pavement made of small,irregular places of stone,such as mosaic.


An organic chemical indicator of acidity or alkalinity;is red in color for pH values below4.5 and blue above 8.3.


A series of coats of arms of the pious founders of certain churches in the Middle Ages and the Renaissance.

Little House

An 18th-century euphemism for an outdoor toilet;a privy.

Liturgical Choir

That part of a choir reserved  for the clergy serving the church.

Liturgically Sited

Said of a church that is laid out in plan so that the congregation faces toward Jerusalem.


1.Connected to a source of voltage.2.Said of a room having an unusually small amount of sound absorption.

Live Boom

A boom on a power that can be raised or lowered without interrupting the digging operation.

Live Edge

The edge of a painted surface which can be blended with fresh paint without having the lap show.

Live Knot

See intergrown knot.

Live Load

The moving or movable external load on a structure;includes the weight of furnishings of a building,of the people,of equipment,etc.but does not include wind load.

Live Part

Any electric component or part which is designed to operate at a voltage different from that of the earth.

Live Room

A room characterized by an unusually small amount of sound absorption.

Live Steam

Steam that has not as yet given up any of its energy and has not yet condensed,e.g.,steam emerging from a boiler.


Descriptive of a piece of electric equipment which is so constructed that there are live parts which can be touched from the front of the assembly.


The acoustical quality of a live room.


The thickening of paint or varnish to an unusable rubbery consistency.

Living Area

See dwelling unit.

Living Room

A space in a dwelling for social use of the residents.

Louver Shielding Angle

The angle between the horizontal plane of a louver grid and the plane beyond which the louver conceals all objects above it.

Louver Window

1.A window having louvers which fill all or part of the opening instead of glass. 2.An open window in the tower of a church.

Louver-type Damper A Damper

1 having multiple blades which are mechanically linked so that they open or close simultaneously.

Louvered Ceiling

A ceiling system consisting of multicellular louvers which shield the light sources mounted above it.

Louvered Shutter

See shutter.


Same as louver.

Low Bid

A bid stating the lowest bid price,including selected alternates,and complying with all bidding requirements.

Low Steel

A soft steel containing a small amount of carbon (less than 0.25%).

Low Voltage

According to ANSI/IEEE standards, a nominal system voltage of 1000 volts or less.

Low-alkali Cement

A portland cement containing a relatively small amount of sodium or potassium or both.

Low-alloy Steel

Steel having an alloy content of less than 8%.


steel Steel having a carbon content less than 0.20%.

Low-density Concrete

Concrete whose oven dry unit weight of less than 50 pounds per cubic foot (800 kg/m3).


contents Building contents having such low combustibility that no self-propagating fire therein can occur.

Low-heat Cement, Type IV Cement

A cement in which there is only limited generation of heat during setting,achieved by modifying the chemical composition of normal portland cement.

Low-noise Lamp

An incandescent lamp having a special internal construction to minimize the generation of audible noise,esp.when operated on certain types of dimmers.

Low-pressure Boiler

According to the ASME Boiler Code,a boiler whose maximum safe working gaugepressure for steam service is 15 pounds per square inch.

Low-pressure Mercury Lamp

A mercury vapor lamp whose partial pressure during operation does not exceed 0.001 atmosphere;fluorescent and germicidal lamps are included in this category.

Low-silicon Bronze

See silicon bronze.

Low-temperature Recovery

The ability of a sealant to recover its original form at low temperature when the deforming load is removed.

Low-voltage Lighting Control

A system of switches,control transformers,relays,and auxiliary devices to control a number of lighting circuits remotely,from one or more locations.

Low-water Alarm

In a system in which water is supplied to a building from a gravity tank,an alarm indicating that the pump supplying the tank has not activated at the low-water condition and that water in the tank is dangerously low.


A type of trailer for hauling construction equipment,with reduced ground clearance that facilitates loading of machinery without an auxiliary ramp.

Lowest Responsive Bid

The lowest bid which is responsive to and complies with the bidding requirements.

Lowest Tender

Same as lowest responsive bid.

LP Gas

Same as liquid petroleum gas.


Abbr.for “low pressure sodium.”


Abbr.for living room.