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Term Definition

A small area within a larger area enclosed by partitions.

Composite Materials

Materials made by combining several layers of different materials.

Composite Panels

Panels having a reconstituted wood core bonded between layers of solid veneer.


The conditions of being shortened (compressed) by force.

Compression Test

A test used to determine the behavior of materials under compression.

Compressive Strength

Measures maximum unit resistance of a material to crushing load. Expressed as force per unit cross-sectional area, e.g., pounds per square inch (psi).

Compressive Stresses

Stresses created when forces push on a member and tend to shorten it.


A mechanical device for increasing the pressure of a gas.

Concentrated Load

Any load that acts on a very small area of a structure.


A mixture of fine and course aggregates, portland cement, and water.

Concrete Footing

Generally, the wide, lower part of a foundation wall that spreads the weight of the building over a larger area. Its width and thickness vary according to weight of building and type of soil on which building is erected.

Concrete Masonry

Factory manufactured concrete units, such as concrete brick or block.

Concrete Pump

A pump that moves concrete through hoses to the area where it is to be placed.


Taking private property for public use, with compensation to the owner, under the right of eminent domain.


A liquid formed by the condensation of vapor.


The process of changing from a gaseous to a liquid state.

Condensation Point

The temperature at which a vapor liquefies if the latent heat is removed at standard ora stated pressure.


A heat-exchanger unit in which a vapor has some heat removed, causing it to form a liquid.


The transfer of heat by direct molecular action.

Conduction, Thermal

Transfer of heat from one part of a body to another part of that body, or to another body in contact, without any movement of bodies involved. The hot handle of a skillet is an example. The heat travels from the bottom of the skillet to the handle by conduction.

Conductivity, Electric

A measure of the ability of a material to conduct electric current.

Conductor, Electric

Wire through which electric current flows.


A steel or plastic tube through which electrical wires are run.

Conforming Use

Lawful use of a building or lot that complies with the provisions of the applicable zoning ordinance.


Describing a cone-bearing tree or shrub.


The process of compacting freshly placed concrete in a form.


A line on a plan that connects all points of equal elevation.

Contour Interval

The vertical distance between adjacent contour lines.

Control Joint

A groove formed in concrete or masonry structures to allow a place where cracking can occur, thus reducing the development of high stresses.


An electric device or a group of devices used to govern the electric power delivered to the equipment to which it is connected.


Process of heat carried from one point to another by movement of a liquid or a gas (i.e., air). Natural convection is caused by expansion of the liquid or gas when heated. Expansion reduces the density of the medium, causing it to rise above the cooler, more dense portions of the medium. Gravity heating systems are examples of the profitable use of natural convection. The air, heated by the furnace, becomes less dense (consequently lighter) and rises, distributing heat to the various areas of the house without any type of blower. When a blower is used, the heat transfer method is called "forced convection."


The process of carrying heat from one spot to another by movement of a liquid or gas. The heated liquid or gas expands and becomes lighter, causing it to rise while the cooler, heavier dense liquid or air settles.


A unit designed to transfer heat from hot water or steam to the air by convection.

Cooling Tower

A heat-transfer device in which the atmospheric air cools warm water flowing through the tower, usually by evaporation.

Corner Brace

Structural framing member used to resist diagonal loads that cause racking of walls and panels due to wind and seismic forces. May consist of a panel or diaphragm, or diagonal flat strap or rod. Bracing must function in both tension and compression. If brace only performs in tension, two diagonal tension members must be employed in opposing directions as "X" bracing.

Corner Lot

A land parcel that fronts on two contiguous streets. The short side is generally considered to be the front of the lot.

Corner Post

Timber or other member forming the corner of a frame. May be solid or built-up as a multi-piece member.


The deterioration of a metal or of concrete by chemical or electrochemical reaction caused by exposure to the weather.

Covalent Bonding

A process in which small numbers of atoms are bonded into molecules.


A restriction of the deed which regluates land use, aesthetic qualities, etc., of an area.


Permanent dimensional deformation occurring over a period of time in a material subjected to constant stress at elevated temperatures.

Creep Test

A test to determine the creep behavior of materials subjected to constant stress at a constant temperature.


A small false roof used to divert water from behind a projection above the roof, such as a chimney.


Short stud such as that used between a door or window header and the top plate.


The central area of a conve surface, such as a road.


A short road with an outlet on one end and a turnaround on the other.


A length of pipe under a road or other barrier used to convey water.


A small roofed structure built on top of a roof, usually to vent the area below the roof.


A low wall of wood or masonry extending above the level of the roof and surrounding an opening in the roof.

Curb Cut

A depression in a curb that provides vehicular access from a street to a driveway.


To chemically cross-link polymer chains by heating and/or adding a chemical agent.


Protecting concrete after placing so that proper hydration occurs.

Curing Agent

Part of a two-part compound that, when added to the second part, sets up the curing action Also referred to as the catalyst.

Current, Electric

The flow of electrons along a conductor.

Curtain Wall

Exterior wall of a building that is supported by the structure and carries no part of the vertical load except its own. Curtain walls must be designed to withstand wind loads and transfer them to the structure.

Cut and Fill

In grading, earth that is removed (cut) or added (fill).

Cycle (Acoustic)

One full repetition of a motion sequence during periodic vibration. Movement from zero to +1 back to zero to -1 back to zero. Frequency of vibration is expressed in Hertz (cycles per second -- see Frequency).


A movable vane used to vary the volume of air passing through a duct, inlet, or outlet.

Damping Capacity

The ability of a material to absorb vibrational energy.


A tool used to level concrete in a form after it has been screeded.

Dead Load

Load on a building element contributed by the weight of the building materials.

Decibel (dB)

A unit for measuring sound energy or power. Adopted for convenience in representing vastly different sound pressures.


Describing trees that shed their leaves annually, as opposed to evergreen.


Separation of elements to reduce or eliminate the transfer of sound, heat or physical loads from one element to the other.


A written instrument that is used to transfer real property from one party to another.


Displacement that occurs when a load is applied to a member or assembly. The dead load of the member or assembly itself causes some deflection as may occur in roofs or floors at mid-span. Under applied wind loads maximum deflection occurs at mid-height in partitions and walls.

Deflection Limitation

Maximum allowable deflection is dictated by the bending limit of the finish material under the required design load (e.g., usually 5 psf for interior partitions).


Change in shape of a body brought about by the application of a force internal or external. Internal forces may result from temperature, humidity or chemical changes. External forces from applied loads can also cause deformation.

Degree Days

The number of degrees that the mean temperature for any day at a particular locatoin is below 65 degrees Fahrenheit.


The removal of water vapor from the air.


A cooling, absorption, or adsorption device used for removing moisture from the air.


The removal of water vapor from any substance.


The separation of the plies in a laminate or plies from a base material.


(1) With regards to materials, a measurement that compares the amount of matter an object has relative to its volume.

(2) In city or site planning, a measure of the number of people, families, etc. that occupy a specified area.


Any absorbent, adsorbent, liquid, or solid that removes water or water vapor from a material.


The process of evaporating or removing water vapor from a material.

Design Load

Combination of weight (dead load) and other applied forces (live loads) for which a building or part of a building is designed. Based on the worst possible combination of loads.

Dew Point

The temperature at which air becomes saturated (100 percent relative humidity) with moisture and below which condensation occurs.



Pumping subsurface water from an excavation to maintain dry and stable working conditions.


A horizontal roof or floor structural element designed to resist lateral loads and transmit them to shear walls (vertical resisting elements).

Dielectric Strength

The maximum voltage a dielectric (nonconductor) can withstand without fracture.


A circular, square, or rectangular air distributing outlet, usually in the ceiling, that has members to discharge supply air in several directions, mixing the supply air with the secondary air in the room.

Dimensional Lumber

Lumber from 2 inches (50.8 mm) up to, but not including, 5 inches (127 mm) thick and 2 inches (50.8 mm) or greater in width.

Direct Current (DC)

Electricity that flows in one direction.

Door Buck

Structural element of a door opening. May be the same element as the frame if frame is structural, as in the case of heavy steel frames.

Double Glazing

Two parallel sheets of glass with an air space in between.

Double Tees

T-shaped precast floor and roof units that span long distances unsupported.

Double-Hung Window

Window sash that slides vertically and is offset in a double track.


(1) In buildings and infrastructure, the system by which excess water is collected, comducted, and dispersed.

(2) In landscaping, the capacity of soil to receive and transmit water.

Dressed Lumber

Lumber having one or more sides planed smooth.


Interruption or offset in an exterior horizontal surface, such as a soffit, immediately adjacent to the fascia. Designed to prevent the migration of water back along the surface.

Drip Line

An imaginary line on the ground described by the outermost branches of a tree.


A vehicular path generally leading from a public street to a structure on private property.

Dry-Press Process

The process used to make bricks when the clay contains 10 percent or less moisture.


A stiff granular grout.


Generic term for interior surfacing material, such as gypsum panels, applied to framing using dry construction methods, e.g., mechanical fasteners or adhesive. See SHEETROCK brand Gypsum Panels.


A hollow tube through which air is circulated.


Capable of being stretched or deformed without fracturing (plastic deformation).


A measure of the capability of a material to be stretched or deformed without breaking.

Dwelling Unit

An independent living area which includes its own private cooking and bathing facilities.

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