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Ulf T. Runesson

Faculty of Natural
Resources Management,
Lakehead University

955 Oliver Road,
Thunder Bay, Ontario,
Canada P7B 5E1

     (807) 343-8784

     (807) 346-7769


Acrylic A synthetic resin used extensively for exterior latex paints and some high quality interior latex paints.
Additives Chemicals which are added to coatings in small amounts to alter the physical or chemical properties of the finish. For example, certain additives can reduce the drying time of alkyd (oil-based) finishes.
Adhesion The union between a coating film and the material with which it is in contact. The latter may be another film of paint (intercoat adhesion) or any other material such as wood.
Adhesive A substance capable of holding materials together by surface attachment. It is a general term and includes cements, mucilage, paste, and glue.
Adhesive, Cold-Setting An adhesive that sets at temperatures below 20°C (68°F).
Adhesive, Construction Any adhesive used to assemble primary building materials such as floor sheathing into components during building construction. The term is most commonly applied to elastomer-based, mastic-type adhesives.
Adhesive, Contact An adhesive which, while apparently dry to the touch, will adhere instantaneously to itself upon contact. The terms contact bond adhesive, or dry bond adhesive, are also used.
Adhesive, Gap-Filling Adhesive suitable for use where the surtaces to be joined may not be in close or continuous contact owing either to the impossibility of applying adequate pressure or to slight inaccuracies in matching mating surtaces.
Adhesive, Hot-Melt An adhesive that is applied in a molten state and forms a bond on cooling to a solid state.
Adhesive, Room-Temperature Setting An adhesive that sets in the temperature range of 20 to 30°C (68 to 86°F).
Adhesive, Working Life (pot life) The period of time during which an adhesive, after mixing with catalyst, solvent, or other compounding ingredients, remains suitable for use.
Alkyds Oil based coatings used in a wide variety of protective coatings, such as floor and deck paint enamels, wall and trim paints, stains, and varnishes.
Annual Growth Ring The layer of wood growth added each growing season to the diameter of the tree. In the temperate zone the annual growth rings of many species such as oaks and pines are readily distinguished because of differences in the cells formed during the early and late parts of the seasons.
Axial Force A push (compression) or pull (tension) acting along the length of a member, expressed in kilonewtons (pounds).
Axial Stress The axial force acting at a point along the length of a member divided by the cross-sectional area of a member, expressed in kilopascals (pounds per square inch).

Back Priming Application of paint to the back of woodwork and exterior siding to prevent moisture from getting into the wood, causing the grain to swell and the paint to peel.
Bark Pocket An opening between annual growth rings that contains bark. Bark pockets appear as dark streaks on radial surtaces and as rounded areas on tangential surtaces.
Beam A structural member loaded on its narrow face.
Bearing The contact area over which one structural element, such as a truss, is supported on another structural element such as a wall.
Bearing Stud Wall An exterior or interior wall designed to act as a structural element by transmitting vertical loads to the foundation.
Birdseye Small localized areas in wood with the fibres indented to form small circular or elliptical figures on the tangential surface which are used for decorative purposes. Sometimes found in sugar maple but only rarely in other hardwood species.
Bleeding The process of diffusion of a coloured substance such as pitch from a knot through a paint or varnish coating, resulting in an undesirable staining or discolouration.
Blistering The formation of dome-shaped projections in paints or varnish films by local loss of adhesion to the underlying surface and lifting of the film. Usually caused by applying paint to a surface containing excessive moisture. It may also be caused by excessive heat, or by using paint with poor adhesive qualities.
Board A piece of lumber that is less than 38mm (2" nominal) in smaller dimension used for sheathing, formwork, or for further manufacture into trim and shaped products, such as siding.
Board Foot A unit of measurement of lumber represented by a board 1 foot long, 12 inches wide, and 1 inch thick or its cubic equivalent. In areas where metric measure has been implemented, the cubic metre may be used to measure timber harvest, but "board foot" remains the unit of measure for lumber production and sale.
Bond Failure Rupture of adhesive bond.
Bond Strength The unit load applied in tension, compression, flexure, cleavage, or shear, required to break an adhesive assembly, with failure occurring in or near the plane of the bond.
Bow A deviation from a straight line (a curve along the face of the piece of lumber) from end to end of a piece, measured at the point of greatest deviation.
Box Beam A built-up beam with solid wood flanges and plywood or woodbase panel product webs.
Brace, Lateral A continuous member connected to a truss chord to maintain the vertical position of the truss during construction.
Brace, Vertical Cross Members placed in a vertical plane between an X pattern between trusses to prevent rotation of the tops of the truss under load.
Broad-leaved trees Trees which shed their leaves in the autumn. Most broadleaved or deciduous trees are hardwoods and have broad leaves.
Building Area The greatest horizontal area of a building above grade within the outside surtace of exterior walls or within the outside surface of exterior walls and the centreline of firewalls.
Building Height The number of storeys contained between the roof and the floor of the first storey.
Burl Swirl or twist in wood grain usually occurring near a knot, valued as the source of highly-figured burl veneers used for ornamental purposes.

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.

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.

Last Modified: January 20, 2014 15:01:06. 
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