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Term Definition
Back Blocking

A short piece of gypsum board adhesively laminated behind the joints between each framing member to reinforce the joint.


Earth filled in around a foundation wall to replace earth removed for construction of the foundation.

Backup Strips

Pieces of wood nailed at the ceiling-sidewall corner to provide fastening for ends of plaster base or gypsum panels.


An electrical device to provide the starting voltage and operating current for fluorescent, mercury, and other electric discharge lamps.

Balloon Frame

Method of framing outside walls in which studs extend the full length or height of the wall.

Bank Measure

The volume of soil in situ in cubic yards.

Bar Joist

Open-web, flat truss structural member used to support floor or roof structure. Web section is made from bar or rod stock, and chords are usually fabricated from "T" or angle sections.


The absense of environmental barriers, permitting free access and circulation by the handicapped.


The amount of concrete mixed at one time.


Narrow strip of wood, plastic, metal or gypsum board used to conceal an open joint.


Ore containing high percentages of aluminum oxide.


Board for the Coordination of Model Codes; part of the Council of American Building Officials Association (CABO).


A straight horizontal structural loadbearing member spanning a distance between supports.


Support area upon which something rests, such as the point on bearing walls where the weight of the floor joist or roof rafter bears.

Bearing Capacity

The ability of a soil to support load.

Bearing Pile

A pile that carries a vertical load.

Bearing Plate

A steel plate placed under a beam, column, or truss to distribute the end reaction from the beam to the supporting member.

Bearing Wall

A wall that supports any vertical load in addition to it's own weight.


To set firmly and permanently in place.


The hard, solid rock formation at or below the surface of the earth.

Bench Mark

A relatively permanent point of known location and elevation.


Bowing of a member that results when a load or loads are applied laterally between supports.

Bending Moment

The algebraic sum of the moments of all forces that are on one side of a give cross-section of a beam.

Bending Stress

A compressive or tensile stress developed by applying non-axial force to structural members.


A process of grinding and concentration that removes unwanted elements from iron-ore before the ore is used to produce steel.

Bentonite Clay

An absorptive clay that swells several times its dry volume when saturated with water.


A convex shapeed bank of earth.


Film-forming ingredient in paint that binds the suspended pigment particles together.


A generic term describing a material that is a mixture of predominantly hydrocarbons in solid or viscous form. It is derived from coal and petroleum.

Bitumenous Coating

Coating formulated by dissolving natural bitumens in an organic solvent.


Excess water that rises to the surface of concrete shortly after it has been poured.


Wood pieces inserted between joists, studs, rafters, and other structural members to stabilize the frame, provide a nailing surface for finish materials, and block the passage of fire between the members.

Board Foot (Bd. Ft.)

Volume of a piece of wood, nominal 19 x 129 x 18. All lumber is sold by the board-foot measure.


Lumber less than 2 inches (50.8 mm) thick and 1 inch (25.4 mm) or greater in width.


A closed vessel used to produce hot water or steam.

Bond Beam

A continuous reinforced beam formed from horizontal masonry members bonded with reinforced concrete.

Bond Breaker

A material used to prevent adjoining materials from adhering.

Bonding Agent

A compound that will hold materials together by bonding to the surfaces to be joined.


The legal recorded property line between two parcels of land.

Box Beam

A structural member of metal or plywood whose cross-section is a closed rectangular box shape.

Box Sill

A type of sill used in frame construction in which the floor joists butt and are nailed to a header joist and rest on the sill.

Braced Frame

A vertical truss used to resist lateral forces.


A pipe in a plumbing system into which no other branch pipes discharge and that discharges into a main or submain.

Branch Circuit

The electrical wiring between the overcurrent protection device and the connected outlets.

Branch Interval

A length of soil or waste stack 8 feet or more in height (equal to one story) within which the horizontal branches from one floor or story of a building are connected to a stack.

Branch Vent

A vent connecting one or more individual vents into a vent stack or stack vent.

Branch, Plumbing

A horizontal run of waste piping that carries waste material to a vertical riser.

Breaking Strength

The point at which a material actually begins to break.

Brick Veneer

Non-loadbearing brick facing applied to a wall to give appearance of solid-brick construction; bricks are fastened to backup structure with metal ties embedded in mortar joints.


Members attached between floor joists to distribute concentrated loads over more than one joist and to prevent rotation of the joist. Solid bridging consists of joist-depth lumber installed perpendicular to and between the joists. Cross-bridging consists of pairs of braces set in an "X" form between joists.

Brinell Hardness

A measure of the resistance of a material to indentation.

Brinnel Hardness Number

A measure of Brinell hardness that is obtained by dividing the load in kilograms by the area of the indentation given in square millimeters.

British Thermal Unit (BTU)

The amount of heat required to raise the temperature of 1 pound (lb) of water by 1 degree Fahrenheit (F).


The characteristic of a material that tends to crack or break without appreciable plastic deformation.

Brown Coat

The second coat of plaster in a three-coat plaster finish.

Buffer Zone

An area separating two different elements or functions.

Buffer, Elevator

Energy-absorbing units placed in the elevator pit.

Buildable Area

The net ground area of a lot that can be covered by a building after required setbacks and other zoning limitations have been accounted for.

Building Code

A set of legal regulations that ensure a minimum standard of health and safety in buildings.

Building Drain

The lowest horizontal piping of a plumbing drainage system that receives the discharge from soil, waste, and other drainage pipes within the building and carries the wasted to the building sewer.

Building Envelope

The enclosure that contains a building's maximum volume.

Building Line

A defined limit within a property line beyond which a structure may not protrude.

Building Sewer

Horizontal piping that carries the waste discharge from the building drain to the public sewer or septic tank.

Built-Up Roof Membrane

A continuous, semi-flexible roof membrane built up fo plies of saturated felts, coated felts, fabrics, or mats that have surface coats of bitumens. The last ply is covered with mineral aggregates, bituminous materials, or a granular-surface roofing sheet.


Curing bricks by placing them in a kiln and subjecting them to a high temperature.


A rigid electric conductor enclosed in a protective busway.


A rigid conduit used to protect a bus running through it.

BX Cable

A cable sheathed with spirally wrapped metal strip identified as Type AC.

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