| Term | Description |
| Tied arch | An arch tied at the base with a tension member. |
| Tier | horizontal course in a unit of lumber. |
| Timber | A general term for natural or sawn wood in a form suitable for building or structural purposes. |
| Timbers | Lumber 5� or more in thickness. |
| Timbers | Lumber 5″ or more in thickness. |
| Tongue and Groove | A joinery method where one board is cut with a protruding “groove” and a matching piece is cut with a matching groove along its edge. |
| Tongue and groove joint | A joint where a ridge or tongue in one piece fits a matching groove in the other. |
| Torque | The amount of force that is needed to turn an object such as a screw or bolt. |
| Toughness | 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. Specific toughness classification are set out in AS 1720.2 SAA Timber Structures Code – Part 2 Timber Properties. |
| Toughness | A property of wood that enables it to absorb a relatively large amount of energy, to withstand repeated shocks, and to undergo considerable deformation before breaking. Trim The finish materials in a building, such as moldings, applied around openings, e.g., window trim, door trim, etc., or at the floor and ceiling of rooms, e.g., baseboard, cornice, etc. |
| Trade names | the accepted regional names given to particular species by industry. Trade names are standardised in AS 2543, Nomenclature of Australian Timbers and AS 1148, Nomenclature of Commercial Timbers imported into Australia. |
| Transverse | Across. A transverse section is a section across the length of a building or room. |
| Tread | The horizontal platform of a stair. |
| Trimmer | The structural member on the side of a framed rough opening to narrow or stiffen the opening. Also the shortened stud (jack stud) which supports a header in a door or window opening. |
| Trimmer | Square-edged boards must pass in a transverse or sideways direction through a battery of saws that precisely end-trim (PET) the lumber to prescribed lengths. |
| Truss | A frame of members in the same plane joined only at their end and all interconnected to form triangles. Primary stresses are axial so that if loads are applied at the joints, the stress in each member is in the direction of its length. |
| Trussed beam | A timber beam reinforced with a trussed metal tension rod. |
| Twist | A spiral distortion along the length of a piece of timber. |
| Twist | A defect referring to a deviation, flatwise, in a piece of lumber, creating the form of a curl or a spiral. |
| Twist | Warping in lumber where the ends twist in opposite directions. (Like twisting a towel) |
| Tyloses | Extensions of parenchyma cells, appearing somewhat like froth, into the pores or vesels of some hardwoods, especially oak and black locust, before or during heartwood formation. Tyloses tend to prevent or greatly impede moisture movement through the pores. |
| Underlayment | A layer of plywood or other manufactured board used as a base material under finished flooring. Underlayment is often used as a substrate to increase the strength and/or smoothness of the flooring. |
| Understorey | That portion of the trees or other vegetation in a forest stand below the main canopy level. |
| Unseasoned timber | Timber in which the average moisture content exceeds 25 %. |
| Urban wood | Used pallets, wooden shipping crates and clean construction wood diverted from the waste stream and chipped for use in making particleboard and MDF. |
| Veneer | A thin layer or sheet of wood. |
| Veneer | A thin sheet of wood cut from a log. |
| Veneer | Thin sheet of wood sliced, sawed, or rotary-cut from a log or a flitch; Rotary-cut Veneer-Veneer cut in a lathe which rotates a log or bolt, chucked in the center, against a knifel Sawed Veneer-Veneer produced by sawing; Sliced Veneer-Veneer that is sliced off a log, bolt, or flitch with a knife. |
| Veneer Logs | Although veneer logs are sold by the board foot, they are never converted to lumber. Veneer logs are turned and rotary cut, that is, the wood is peeled off the log by turning it against a stationary knife. The sheets of wood may be laminated into plywood or laminated veneer lumber (LVL) products. |
| Veneer Sheets | Thin sheets of wood of a specified thickness that are peeled, sliced, or sawn from logs for use in plywood, paneling, and furniture. |
| Veneer-core Plywood | Plywood made from three or more pieces of veneer glued up in alternating grain patterns. |
| Veneering | Facing a substrate with a thin layer of ornamental wood. |
| Vertical integration | In the forest products industry, a vertically integrated company grows its own trees, makes products from them, then makes other products from fiber leftovers from the initial manufacturing operation, then converts and adds value to all these products. |
| Vertically laminated timber | Laminated timber designed to resist bending loads applied parallel to the wide face of the laminations. For vertical loads, this means that the wide face runs vertically. |
| Vessels | Relatively large diameter hardwood cells that have open ends and are arranged one above the other to form a continuous tube. The openings of the vessels on the surface of a piece of wood are usually referred to as pores. |
| Wane | A lumber defect referring to the absence of wood or the presence of bark along an edge or corner. |
| Wane | The absence of wood on any face or edge of a piece of timber, leaving exposed the original underbark surface with or without bark. |
| Wane | A lumber defect referring to the absence of wood or the presence of bark along an edge or corner. |
| Want | The absence of wood, other than wane, from the arris or surface of a piece of timber. |
| Warp | A lumber defect referring to any combination of bow, crook, cup, or twist. |
| Warp | Any variation from a true and plane surface. It includes bow, cup and twist and is often caused by irregular seasoning. |
| Warp | A defect in lumber characterized by a bending in one or more directions. |
| Warp | A lumber defect referring to any combination of bow, crook, cut, or twist. |
| Water repellent | A liquid that penetrates wood which, after drying, materially retards changes in moisture content and in dimensions without adversely altering thedesirable properties of wood. |
| Water-repellent preservative | A water repellent that contains a preservative which, after application to wood and drying, accomplishes the dual purpose of imparting resistance to attack by fungi or insects and also retards changes in moisture content. |
| Wavy figure | Markings in the form of waves or undulations. Figures with large undulations are described as ‘wavy’, while others with small, irregular undulations are ‘curly’, and those with small, regular undulations are ‘fiddleback’. |
| Weatherboard | Boards that cover external surfaces and overlap to keep out the rain. |
| Weathering | The mechanical or chemical disintegration and discoloration 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 variation in moisture content. Weathering does not include decay. |
| Weathering | The cumulative effect of surface deterioration in wood exposed to the weather and unprotected by paint or other means. It is also the mechanical and chemical disintegration and discoloration of wood surface caused by exposure to light, dust and sand carried by winds. It does not include decay. |
| Web | Any transverse lateral stiffener. |
| Weekly pricing guides | Reports published weekly by independent companies charting the prices of many common lumber items. |
| Wetwood | Green wood with an abnormally high moisture content that generally results from infections in living trees by anaerobic bacteria, but may also result from water logging during log ponding. The condition can occur in both softwoods and hardwoods; the green lumber is usually difficult to dry without defects. Although difficult to recognize, wetwood is often characterized by a translucent, watersoaked appearance and a sour or rancid odor. |
| White lumber | Lumber that has not been treated. |
| Whole tree chips (WTC) | Some mechanized loggers reduce trees that are not otherwise marketable as logs to whole tree chips to be sold to wood energy plants. Whole tree chips differ from mill chips in that they include the bark, sapwood, and heartwood of the tree, as well as branches and leaves (from deciduous or hardwood trees) or needles (from evergreen or softwood trees). |
| Wholesaler | One who purchases material from a producer or remanufacturer, for resale to retailers, industrial users, etc., While also providing for transportation, credit, and other services. |
| Wild figure | Irregular markings. |
| Wind bracing | Bracing members required to resist the forces on a structure resulting from wind pressure. |
| Wind post | A column that stiffens a framed wall against wind loads. |
| Wood | The hard compact fibrous substance of which trees and shrubs are largely composed. |
| Wood Biodeterioration | The destruction and eventual reduction of wood to its component sugars and lignin elements through attack by organisms such as, fungi, and certain insects, for instance, termites.
Blue Stain |
| Wood energy plants | Electric generating plants that burn wood chips as fuel to produce steam and electricity. A number of these plants were built in the 1970’s subsidized by the federal government and electric utilities when the price of foreign oil rose dramatically. |
| Wood Preservation | The introduction of preservatives into wood to protect it from agents of destruction and bio-deterioration, such as fire, insects, and fungi. |
| Work to Maximum Load | In bending, it represents the ability of wood (or other materials) to absorb shock with some permanent deformation and more or less injury to the piece. It is a measure of the combined strength and toughness of wood under bending stresses. |
| Workability | The degree of ease and smoothness of cut obtainable with hand or machine tools. |
| Working Life (Pot Life) | The amount of time after mixing that a glue or paint remains usable. Often used when referring to two-part epoxy and polyester glues. |
| Wormholes | Holes and channels cut in wood by insects. |
| X | The drafting symbol for a cross section of an object. |
| Xylem | The cellular tissue inside a tree’s bark often called wood.� |
| Yield | The proportion of the log converted into lumber is the product that produces the greatest value. The percentage of the log that winds up in as lumber (54-55%), sawdust (4-19%), or chips (27-41%) depends upon: 1) Thickness of lumber being cut; 2) Skill of the sawyer; 3) Type of headsaw; 4) Saw kerf; 5) Losses in edging, trimming, drying, and surfacing |