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Camber An upward vertical displacement built into a truss or glued-laminated beam to offset deflection.
Cambium A thin layer of tissue between the bark and the wood in a tree which repeatedly subdivides to form a new wood and bark cells.
Cantilever The part of a truss or structural member that extends beyond its support.
Cell General term for the minute units of wood structure, including wood fibres, vessel segments and other elements.
Cellulose The carbohydrate that is the principal constituent of wood. It forms the framework of wood cells.
Chalking The formation of a powdery coating on the surface of a paint film caused by disintegration of the binding medium by action of the weather. Characteristics - Distinguishing features which, by their extent, number and character, determine the quality of a piece of lumber.
Check A lengthwise separation of the wood which extends across the rings of annual growth, usually resulting from stresses set up in wood during seasoning.
Chord, Bottom A horizontal or inclined member that establishes the lower edge of a truss, usually carrying combined tension and bending stresses.
Chord, Top An inclined or horizontal member that establishes the upper edge of a truss, usually carrying combined compression and bending stresses.
Clear Span Horizontal distance between interior edges of supports.
Combined Stress The combination of axial and bending stresses acting on a member simultaneously, such as occurs in the bottom chord (usually tension plus bending) of a truss.
Compression Failure Deformation of the wood fibres resulting from excessive compression along the grain either in direct end compression or in bending. In surfaced lumber, compression failures may appear as fine wrinkles across the face of the piece.
Concentrated Load Loading centred on a certain point (such as from roof-mounted equipment) as opposed to being equally distributed along the length of a member.
Conditioning The exposure of a wood to the influence of a prescribed atmosphere for a stipulated period of time, or until a stipulated relation is reached between material and atmosphere.
Connector, Timber Metal ring, plate, or grid embedded in the wood of adjacent members to increase the strength of the joint.
Cup A distortion of a board in which there is a deviation from a straight line across the width of the board
Cure The setting of an adhesive by chemical reaction, usually accomplished by the action of heat or a catalyst with or without pressure.
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Dead Load Any permanent load resulting from the weight of building materials or installed equipment.
Decay The decomposition of wood substance caused by the action of wood- destroying fungi, resulting in softening, loss of strength, weight, and often in change of texture and colour.
Decay, Brown Rot Wood decay in which the attack concentrates on the cellulose and associated carbohydrates rather than on the lignin, producing a light to dark brown pliable residue and sometimes referred to as dry rot.
Decay, Heart Rot Any rot characteristically confined to the heartwood originating in the living tree.
Decay, Incipient The early stage of decay that has not proceeded far enough to soften or otherwise apparently impair the hardness of the wood. It is usually accompanied by a slight discolouration or bleaching of wood.
Decay, White-Rot Decay attacking both the cellulose and the lignin, producing a generally whitish residue that may be spongy or stringy.
Deflection Displacement of a member usually due to dead and live loads.
Delamination The separation of layers in laminated wood or plywood because of failure of the adhesive, either within the adhesive itself or at the interface between the adhesive and the wood.
Density The mass of wood substance enclosed within the boundary surfaces of a wood-plus-voids complex having unit volume. It is variously expressed as pounds per cubic foot, kilograms per cubic metre, or grams per cubic centimetre, at a specified moisture content.
Diaphragm A horizontal or nearly horizontal roof or floor structural element designed to resist lateral loads (wind and earthquake loads) and transmit these loads to the vertical resisting elements (shearwalls).
Dressed Size The cross-sectional dimensions of lumber after planing.
Dry, Air Process of drying or seasoning lumber naturally by exposure to air.
Dry, Kiln Process of drying or seasoning lumber naturally by placing the lumber in a kiln and exposing the lumber to heat for a prescribed period of time.
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