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    Dictionary of Wood Product and Construction Terminology: CWC

    (Source: Canada Wood Council

    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.


    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.


    A structural member loaded on its narrow face.


    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.


    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.


    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.


    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.


    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.


    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.


    Swirl or twist in wood grain usually occurring near a knot, valued as the source of highly-figured burl veneers used for ornamental purposes.


    An upward vertical displacement built into a truss or glued-laminated beam to offset deflection.


    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.


    The part of a truss or structural member that extends beyond its support.


    General term for the minute units of wood structure, including wood fibres, vessel segments and other elements.


    The carbohydrate that is the principal constituent of wood. It forms the framework of wood cells.


    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.


    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.


    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.


    A distortion of a board in which there is a deviation from a straight line across the width of the board


    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.


    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.


    Displacement of a member usually due to dead and live loads.


    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.


    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.


    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.

    Edge Distance

    The distance from the edge of a member to the centre of the nearest fastening.

    End Distance

    The distance measured parallel to the axis of a piece from the centre of a fastening to the square-cut end of the member (if the end of the member is not square-cut, a formula is used to calculate the end distance).

    Equilibrium Moisture Content

    The moisture content at which wood neither gains nor loses moisture when surrounded by air at a specified relative humidity and temperature.


    A substance added to an adhesive to reduce the amount of primary binder required per unit area.

    Extender Pigment

    A coating additive which imparts special properties (for example. to give exterior varnish protection from ultra-violet light degradation).


    A broad term including materials of widely varying densities manufactured by pressing wood fibres into panels sometimes used for sheathing.

    Fibre Saturation Point

    The moisture content of wood, usually around 25-30 percent, at which the cell walls are saturated and the cell cavities are free of water.


    The pattern produced in a wood surface by annual growth rings, rays, knots, or irregular colouration.


    A substance used to fill the holes and irregularities in planed or sanded surfaces to decrease the porosity of the surface before applying finish coatings. As applied to adhesives, a filler is a substance added to an adhesive to improve its working strength or other properties.

    Fine Finish

    Coatings of paint, varnish, lacquer, wax or other material applied to high quality wood surfaces to protect and enhance their durability and appearance.

    Fine Woodwork

    Products such as trim, panelling used for architectural woodwork to provide a high quality decorative appearance to rooms.


    An end joint made up of several meshing wedges or fingers of wood bonded together with an adhesive. Fingers are sloped and may be cut parallel to either the wide or narrow face of the piece.

    Factored Load

    The product of a specified load and its applicable load factor as used in Limit States Design.

    Factored Resistance

    The product of resistance and its applicable resistance factor as applied in Limit States Design.


    A long narrow, tapering wood cell closed at both ends.

    Fire Compartment

    An enclosed space in a building that is separated from all other parts of the building by enclosing construction. This provides a fire separation which has a required fire-resistance rating.

    Fire-Resistance Rating

    The time in hours or minutes that a material or assembly of materials will withstand the passage of flame and the transmission of heat when exposed to fire under specified conditions of test and performance.


    A chemical or preparation of chemicals used to reduce flammability or to retard the spread of a fire over the surtace.

    Fire-Retardant Coating

    A coating applied by brush, roller, or sprayer which reduces the burning characteristics of wood surfaces.

    Fire-Retardant Treated Wood

    Wood or a wood product that has had its surface-burning characteristics, such as flame- spread, rate of fuel contribution and density of smoke developed, reduced by pressure treating with fire retardant chemicals.

    Fire Separation

    A construction assembly that acts as a barrier against the spread of fire. (A fire separation may or may not have a fire-resistance rating.)


    A type of fire separation of noncombustible construction that subdivides a building or separates adjoining buildings to resist the spread of fire and that has a fire-resistance rating as prescribed in the codes and has structural stability to remain intact under fire conditions for the required fire rated time.

    Flame-Spread Rating

    An index or classification indicating the extent of spread of flame on the surface of a material, or an assembly of materials, as determined in a standard fire test as prescribed in the building code


    Lifting of the paint from the underlying surface in the form of flakes or scales.

    Girder A large or principle beam used to support concentrated loads at isolated points along its length.

    Glulam Structural wood product made by bonding together laminations of dimension lumber.

    Glulam Rivet A nail-like oval shaped fastener used in combination with predrilled steel plates to connect glulam members (approved for use in Canada and the U.S.).

    Gloss The degree of reflection of a coating film. Paints, varnishes, and lacquers having a lot of reflection are said to be glossy, while those having a low level of reflection are said to be flat.

    Grade A classification of lumber or other wood products based on criteria of quality such as natural characteristics and strength.

    Grade stamp A stamp placed on lumber to denote its grade.

    Grain The direction, size, arrangement, appearance or quality of the fibre in wood or veneer.

    Grain, Close-Grained Wood Structure of some hardwoods, such as birch and maple, having narrow, inconspicuous annual rings with little difference in pore size between springwood (early wood) and summerwood (late wood).

    Grain, Cross A pattern in wood in which the fibre and other longitudinal elements deviate from a line parallel to the sides of the piece as a result of sawing or as a result of inconsistent grain direction as a growth characteristic.

    Grain, Edge (quarter-sawn, quarter-cut) Terms referring to timber or veneer cut in a plan approximately at right angles to the annual rings.

    Grain, Flat (flat-sawn, plain-sawn) Lumber that has been sawed parallel to the length of the log and approximately tangent to the growth rings.

    Grain, Open-Grained Wood Structure of some hardwoods such as oak, chestnut and ash in which there is a distinctive difference in the pore sizes between springwood (early wood) and summerwood (late wood). The term coarse is also sometimes used to describe open grain woods.

    Grain, Spiral-Grain An arrangement of the fibres in a piece of timber or veneer which results from their growth in a spiral direction around the trunk of the tree.

    Green (unseasoned) Freshly sawed lumber, or lumber that has received no intentional drying. Wood that has become completely wet after immersion in water would not be considered green, but may be said to be in the green condition.


    A panel manufactured primarily from interfolded wood fibres consolidated under heat and pressure in a hot press and used, for example, in the manufacture of siding products.

    Hardwood (deciduous) Trees

    One of the botanical groups of trees that have broad leaves, in contrast to the conifers or softwoods. The term does not necessarily refer to the actual hardness of the wood.


    A single member composed of two or more wood members, securely fastened together and used to increase load carrying capability at wall or floor or widow openings.


    The wood extending from the true centre to the sapwood, and whose cells no longer participate in the life processes of the tree. Hearfwood may contain gums, resins, and other materials that usually make it darker and more decay resistant than sapwood.

    Heavy Timber Construction

    A type of combustible construction in which a degree of fire safety is attained by placing limitations on the sizes of wood structural members and on thickness and composition of wood floors and roofs and by the avoidance of concealed spaces under floors and roofs.


    Point on truss at which the top and bottom chords intersect.


    A cellular separation in the interior of a wood piece, usually along the wood grain, a result of internal stress. It normally occurs during kiln drying, particularly in white or red oak, when too much heat is applied too rapidly.

    Importance Factor

    A factor applied to factored loads, other than dead load, to take into account the consequence of collapse as related to the use and occupancy of the structure, as in Limit States Design.


    The swelling of a fire- retardant coating when heated, resulting in the formation of low-density film which provides a degree of surface flame-spread resistance.

    Joint, Butt

    An end joint formed by abutting the squared ends of two pieces.

    Joint, End

    A joint made by bonding two pieces of wood together end to end, usually by finger or scarf joint.

    Joint, Scarf

    An end joint formed by joining with adhesive the ends of two pieces that have ben tapered or bevelled to form sloping plane surfaces.


    One of a series of parallel beams used to support floor and ceiling loads, supported in turn by larger beams, girders, or bearing walls.


    That portion of a branch or limb that has been surrounded by subsequent growth of the stem. The shape of the knot as it appears on a lumber surface depends on the angle of the cut relative to the long axis of the knot.

    Knot, Loose

    A knot which is not held firmly in place by growth or position and which cannot be relied upon to remain in place.

    Knot, Pin

    A knot that is not more than 12.5mm (1/2") in diameter.

    Knot, Sound

    A knot that is solid across its face, at least as hard as the surrounding wood, and shows no indication of decay.

    Laminate, Wood

    A product made by bonding layers of wood or other material to a wood substrate.

    Laminated Veneer Lumber (LVL)

    A structural lumber product manufactured from veneers laminated so that the grain of all veneers run parallel to the axis of a member.


    A synthetic resin used in the manufacture of water soluble paint coatings. PVA and acrylic are two types of latex resins used to make latex coatings.

    Level or Soffit Return

    Lumber filler placed horizontally from the end of an overhang to the outside wall to form a soffit.

    Light Framing

    The use of dimension lumber, trusses, and other small cross- section members to provide support and enclosure for a building.


    The second most abundant constituent of wood after cellulose. It is the thin cementing layer between the wood celIs.

    Limit State

    A condition of a structure at which the structure ceases to fulfil the design function as applied in Limit States Design.

    Live Load

    Any loading that is of a temporary nature such as snow, wind, earthquake, and construction loads.

    Load Combination Factor

    A factor applied to the factored loads in Limit States Design, other than dead load, to take into account the reduced probability of a number of loads from different sources acting simultaneously as applied to Limit States Design.

    Load Duration

    The period of continuous application of a specified load, or the aggregate of periods of intermittent applications of the same load.

    Load Factor

    A factor applied to a specified load that, for the limit state under consideration, takes into account the variability of the loads and load patterns as applied to Limit States Design.


    The product of the saw and planing mill not further manufactured than by sawing, resawing, passing lengthwise through a standard planing machine, cross- cutting to length, and grading.

    Lumber, Boards

    Lumber that is less than 38mm (2" nom.) thick and 38mm (2" nom.) or more wide.

    Lumber, Dressed Sized

    The dimensions of lumber after being surfaced with a planing machine.

    Lumber, Machine Stress-Rated (MSR)

    Lumber which has been mechanically evaluated to determine its stiffness and bending strength.

    Lumber, Matched

    Lumber that is edge dressed and shaped to make a close tongue and groove joint at the edges or ends, when laid edge to edge, or end to end.

    Lumber, Nominal Size

    The size of lumber after sawing and prior to surface finishing by planing.

    Lumber, Patterned

    Lumber that is shaped to a pattern or to a moulded form in addition to being surface planed.

    Lumber, Rough

    Lumber that has not been dressed (surfaced) but which has been sawed, edged, and trimmed.

    Lumber, Shiplapped

    Lumber that is edge dressed to make a lapped joint.

    Lumber, Sizes of

    For metric measure, lumber size is based on actual size rounded to the nearest millimetre. For Imperial measure, lumber size is usually expressed in terms of nominal size which is the size before surfacing. The dressed size is usually 12 to 19mm (1/2 to 3/4") less than the nominal or rough size. For example, a 2" x 4" stud after dressing measures about 1-1/2" x 3-1/2".

    Lumber, Structural

    Lumber which has strength in relation to the anticipated structural end use, as a controlling factor in grading or selecting.

    Lumber, Visually Stress-Graded

    Lumber that has been graded for strength based on visual appearance, as opposed to MSR lumber which is evaluated mechanically and checked visually.

    Lumber, Dimension

    Lumber 38 to 102mm (2" to 4" nom.) in smaller dimension

    Medium Density Fibreboard (MDF)

    A panel product, widely used as a substitute for plywood, particleboard and solid lumber; manufactured in a process where wood fibres, resin and wax is compressed under high pressure to form a panel.


    Planed and patterned lumber for finish work in buildings, including items such as sash, doors, cornices, panelwork, and other items of interior or exterior trim, but not flooring or siding.

    Mineral Spirits

    A petroleum derived solvent similar to gasoline, used primarily for thinning alkyd and other oil based coatings such as paint, stain, and varnish

    Moisture Content

    The amount of water contained in the wood, expressed as a percentage of the weight of the oven-dry wood.


    A wood strip having a curved or projecting surface used for decorative purposes.

    Noncombustible Construction

    A factor applied to factored loads, other than dead load, to take into account the consequence of collapse as related to the use and occupancy of the structure, as in Limit States Design.

    Oriented Strandboard (OSB)

    A panel product, used for sheathing, made from strands with the face wafers oriented in the long direction of the panel to provide additional strength in that direction.


    A thin layer of paper, plastic, film, metal foil, or other material bonded to one or both faces of panel products, or to lumber, to provide a protective or decorative face, or a base for painting.


    A coating containing enough pigment to create an opaque solid film after application as a thin layer.

    Paint, Enamel

    A coating product characterized by ability to form a uniform hard film used for flooring and other high wear applications. Enamels may be obtained in a full range of colours and usually in gloss or semi-gloss.

    Panel Point

    The point of intersection where the web or webs of a truss meet a chord.

    Parallel Strand Lumber (PSL)

    A structural wood product made by gluing together long strands of wood which have been cut from softwood veneer.


    The small cylinder of primary tissue of a tree stem around which the annual rings form.


    The accumulation of resin in wood.

    Pitch Pocket

    An opening between growth rings which usually contains or has contained resin or bark or both.

    Panel, Exterior

    A general term for plywood or OSB/waferboard, bonded with a type of adhesive that by systematic tests and service records has proved highly resistant to weather.

    Panel, Interior

    A general term for a panel made from a type of adhesive which is not resistant to moisture and is therefore limited to uses where protection from moisture is provided.


    A glued wood panel made up of thin layers of veneer with the grain of adjacent layers at right angles, or of veneer in combination with a core of lumber or of reconstituted wood.

    Plywood, Standard Construction

    Panels constructed of pairs of plies that are balanced as to grain direction and thickness about the central ply or panel centreline, in which the grain of each ply is at right angles to at least one other ply.

    Plywood, Modified Construction

    Panels which are not standard thickness or which have an even number of plies.

    Plywood Stressed-Skin Panel

    A form of construction in which outer skins of plywood are applied over internal frame members to form a rigid structural element.


    A paint and varnish resin which imparts good abrasion resistance and marketed under several trade names such as varathane, urethane, and durathane.


    A timber with larger dimension not more than 51mm (2") greater than the smaller dimension and usually graded for use as a column.


    Any substance effective in preventing the development and action of wood-rotting fungi, borers of various kinds, and harmful insects that cause the deterioration of wood.


    The process of impregnating wood with preservative or fire retardant chemicals by placing the wood and chemical in a pressure chamber.

    Pressure-Treating, Empty-Cell Process

    Pressure treating process in which back pressure from air drives out part of the injected preservative or chemical to leave the cell walls coated but the cell cavity mostly devoid of chemical.

    Pressure-Treating, Full-Cell Process

    Pressure treating process in which a vacuum is drawn to remove air from the wood before admitting the preservation, resulting in a heavy absorption and retention of preservative due to the cells being almost filled.


    One or more preliminary base coats of paint system, applied prior to the application of finishing coats.


    One of a series of structural members of a roof designed to support roof loads.

    Raised Grain

    A roughened condition of the surface of dressed lumber in which the hard latewood is raised above the softer earlywood but not torn loose from it.


    Strip of cells extending radially within a tree and varying in height from a few cells in some species to 100mm (4") which cause an appealing grain pattern.


    An ingredient of coatings which acts as a binder and gives the coating physical properties such as hardness and durability.

    Resin (natural)

    Inflammable, water- soluble, vegetable substances secreted by certain plants or trees, and characterizing the wood of many coniferous species.


    A cut made lengthwise in a wood member, parallel to the grain.


    The watery fluid that circulates through a tree carrying the chemical food that enables the tree to grow.

    Sanding Sealer

    A preparation coating which seals the wood in preparation for topcoating and which is easy to smooth by sanding.

    Sandwich Panel, Structural

    Panels made of parallel framing members separated by expanded polystyrene which act as structural units in resisting horizontal or vertical loads.

    Sandwlch Panel, Non-Structural

    A panel comprised of a foam core with plywood or OSB bonded to each face designed to enclose but not to be the main load- carrying elements.


    The wood of pale colour near the outside of the log. Under most conditions sapwood is more susceptible to decay than heartwood.


    The process of drying lumber either naturally, or in a kiln, to a moisture content appropriate for the conditions and purposes for which it is to be used.

    Service Condition, Dry

    A service condition in which the average equilibrium moisture content over a year is 15 percent or less and does not exceed 19 percent.

    Servlce Condition, Wet

    All service conditions other than dry.

    Serviceability Limit States

    Those states which restrict the intended use and occupancy of the structure including deflection, joint slip, vibration, and permanent deformation as applied in Limit States Design


    A separation along the grain usually occurring between the rings of annual growth


    A western red cedar roofing and sidewall product made by splitting blocks of cedar, as opposed to shingles which are manufactured by sawing.


    A wall or partition designed to transfer lateral loads (wind and earthquake loads) from abutting walls and roof to the foundation.


    The decrease in the dimension of wood resulting from a decrease of moisture content and generally occurring to the greatest extent between about 20 and 30 percent moisture content.

    Strength Limit States

    Those states concerning safety and including the maximum load-carrying capacity of the structural materials of the connection as they relate to Limit States Design.

    Slope (Pitch)

    The ratio of vertical rise to horizontal run for inclined members (generally expressed as 3/12, 4/12, 5/12 etc.).

    Slope of grain

    The angle between the direction of the grain and the axis of a piece of lumber, expressed as a ratio.

    Softwoods (conifers)

    One of the botanical groups of trees that in most cases have needlelike or scalelike leaves.


    Volatile liquids used in paint, stain, varnish, and lacquer coatings which give the coating workability and which, upon evaporation, allow the resin to harden.


    A distinct sort or kind of tree having some characteristics or qualities in common that distinguishes it from other groups.

    Species Group

    The combining of species into commercial groups because of their similarity in appearance and physical properties.

    Springwood (early wood)

    The portion of the annual growth ring that is formed during the early part of the season's growth; it is usually less dense, lighter in colour, and weaker mechanically than summerwood.

    Stain (natural)

    A discolouration on or in lumber, other than its natural colour.

    Stain (chemical)

    A solution or suspension of colouring matter in a vehicle designed to penetrate a surface and colour the wood, without hiding surface characteristics and providing some protection.


    One of a series of vertical load bearing members used as supporting elements in walls and partitions.

    Stud Wall System

    Combination of studs and sheathing panels or boards on one or both sides designed to bear vertical loads and to provide shearwall action.


    The portion of the annual growth that is formed after the springwood (early wood) formation has ceased. It is usually more dense and stronger mechanically than springwood (early wood).


    The relative size and arrangement of the wood cells.

    Thermoplastlc Glues and Resins

    Glues and resins that are capable of being repeatedly softened by heat and hardened by cooling.

    Thermosetting Glues and Resins

    Glues and resins that are cured with heat but do not soften when subsequently subjected to high temperatures.


    A piece of lumber 140mm (5-1/2") or more in smaller dimension.

    Timber Connector

    A metal ring or plate that, by being embedded in adjacent wood faces or in one wood face, acts in shear to transmit loads from one timber to another, or from a timber to a bolt and, in turn, to a steel plate or another connector.


    A quality of wood which permits the material to absorb a relatively large amount of energy, to withstand repeated shocks, and to undergo considerable deformation before breaking.


    An assembly of members combined to form a rigid framework. All members are interconnected to form triangles. Light frame trusses are made from dimension lumber restrained by toothed plates. Heavy trusses are made for large members restrained by bolts and connectors or glulam rivets.

    Truss Plate

    A light steel plate fastening, intended for use in structural lumber assemblies, that may have integral teeth of various shapes and configurations.


    Warping in which one corner of a piece twists out of the plane of the other three.


    A paint coating which lacks pigment and which gives a transparent or translucent finish to wood.

    Veneer, Rotary Cut

    Veneer cut in a lathe which rotates a log, chucked in the centre, against a knife.

    Veneer, Sawn

    Veneer produced by sawing.

    Veneer, Sliced

    Veneer that is sliced from a log with a knife.


    A mat-formed structural panel board made of wood wafers, randomly arranged and bonded together with a waterproof and boilproof binder.

    Wood Preservative

    Means any suitable substance that is toxic to fungi, insects, borers, and other living wood-destroying organisms.


    Bark or lack of wood on the edge or corner of a piece of wood resulting from the piece being sawn from near the outer circumference of a sawlog.


    Any deviation from a true or plane surface. Warp includes bow, crook, cup and twist, and any combination of these.

    Water-Repellent Preservative

    A water repellent that contains a preservative, accomplishing the dual purpose of imparting resistance to attack by fungi or insects. It also retards changes in moisture content.


    The mechanical or chemical disintegration and discolouration of the surface of wood caused by exposure to light, the action of dust and sand carried by winds, and the alternate shrinking and swelling of the surface fibres with the continual variation in moisture content, brought by changes in the weather.


    Members that join the top and bottom chords to form the triangular patterns that give truss action. They usually carrying tension or compression stresses.

    Wood Cells (vessels)

    The basic units comprising wood having open ends and set one above the other so as to form continu- ous tubes. The openings of the vessels on the surface of a piece of wood are usually referred to as pores.

    Wood I-joist, Prefabricated

    A structural wood member made by using adhesive to attach wood flanges (LVL, MSR, or high quality dimension lumber) to a plywood or OSB web.


    The degree of ease and smoothness with which wood can be worked.

    Water Repellent

    A liquid that penetrates wood which retards changes in moisture content and in dimensions without adversely altering the desirable qualities of wood.

    CRDBER, at CBS, BCEE, ENCS, Concordia,