1 furnished with or made of wood or timbers; "timbered walls" [ant: untimbered]
2 covered with growing timber; "thickly timbered ridges clothed with loblolly pine and holly"; "hills timbered up to their summits"
Lumber or timber is wood in any of its stages from felling through readiness for use as structural material for construction, or wood pulp for paper production. Timber often refers to the wood contents of standing, live trees that can be used for lumber or fiber production, although it can also be used to describe sawn lumber whose smallest dimension is not less than 5 inches (127 mm).
Lumber is supplied either rough or finished. Besides pulpwood, rough lumber is the raw material for furniture-making and other items requiring additional cutting and shaping. It is available in many species, usually hardwoods. Finished lumber is supplied in standard sizes, mostly for the construction industry, primarily softwood from coniferous species including pine, cedar, hemlock, fir and spruce, but also some hardwood for high-grade flooring.
Dimensional lumberDimensional lumber is a term used for lumber that is finished/planed and cut to standardized width and depth specified in inches. Examples of common sizes are 2×4 (also two-by-four and other variants such as four-b'-two in Australia), 2×6, and 4×4. The length of a board is usually specified separately from the width and depth. It is thus possible to find 2×4s that are four, eight, or twelve feet in length. In the United States the standard lengths of lumber are 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 feet. Solid dimensional lumber typically is only available up to lengths of 24 ft, yet since builders have a need for lengths beyond that for roof construction (rafters), builders use "finger-jointed" lumber that can be up to 36 ft long in 2×6 size (see Engineered Lumber below). Finger-jointed lumber is also widely used for smaller lengths like studs, the vertical members of a framed wall. Pre-cut studs save a framer a lot of time as they are pre-cut by the manufacturer to be used in 8 ft, 9 ft & 10 ft ceiling applications, which means they have removed a few inches of the piece to allow for the sill plate and the double top plate with no additional sizing necessary by the framer.
In the Americas, two-bys (2×4s, 2×6s, 2×8s, 2×10s, and 2×12s), along with the 4×4, are common lumber sizes used in modern construction. They are the basic building block for such common structures as balloon-frame or platform-frame housing. Dimensional lumber made from softwood is typically used for construction, while hardwood boards are more commonly used for making cabinets or furniture.
The nominal size of a board varies from the actual size of the board. This is due to planing and shrinkage as the board is dried. This results in the final lumber being slightly smaller than the nominal size. Also, if the wood is surfaced when it is green, the initial dimensions are slightly larger (e.g. 1/16 in bigger for up to 4 in nominal lumber, ⅛ in for 5 in and 6 in nominal lumber, ¼ in bigger for larger sizes). As the wood dries, it shrinks and reaches the specified actual dimensions.
Non-North American sizesOutside North America sizes of timber can vary slightly. Sizes are, in some cases, based on the imperial measurement and referred to as such; in other cases the sizes are too far removed from the imperial size to be referred to by imperial measurement. Lengths are sold every 300 mm (a metric approximation of 1 ft). Common sizes are similar to the North American equivalent; 2.4, 2.7, 3.0, 3.6, 4.2, 4.8, 5.4, 6.0.
HardwoodsIn North America sizes for dimensional lumber made from hardwoods varies from the sizes for softwoods. Boards are usually supplied in random widths and lengths of a specified thickness, and sold by the board-foot (144 cubic inches, 1/12th of a cubic foot). This does not apply in all countries, for example in Australia many boards are sold to timber yards in packs with a common profile (dimensions) but not necessarily of consisting of the same length boards. Hardwoods cut for furniture are cut in the fall and winter, after the sap has stopped running in the trees. If hardwoods are cut in the spring or summer the sap ruins the natural color of the timber and deteriorates the value of the timber for furniture.
Also in North America hardwood lumber is commonly sold in a “quarter” system when referring to thickness. 4/4 (four quarters) refers to a one-inch thick board, 8/4 (eight quarters) is a two-inch thick board, etc. This system is not usually used for softwood lumber, although softwood decking is sometimes sold as 5/4 (actually one inch thick).
Engineered lumberEngineered lumber is lumber created by a manufacturer and designed for a certain structural purpose. The main categories of engineered lumber are:
- Laminated Veneer Lumber (LVL) – LVL comes in 1-3/4 inch thicknesses with depths such as 9-1/2, 11-7/8, 13, 16, 18, or 24 inches, and are typically doubled or tripled up. They function as beams to provide support over large spans, such as removed support walls and garage door openings, places where dimensional lumber isn't structurally sound to use, and also in areas where a heavy load is bearing from a floor, wall or roof above on a somewhat short span where dimensional lumber isn't practical. This type of lumber cannot be altered by holes or notches anywhere within the span or at the ends, as it compromises the integrity of the beam, but nails can be driven into it wherever necessary to anchor the beam or to add hangers for I-joists or dimensional lumber joists that terminate at an LVL beam.
- Wood I-joists – Sometimes called "TJI®" or "Trus Joists®", both of which are brands of wood I-joists, they are used for floor joists on upper floors and also in first floor conventional foundation construction on piers as opposed to slab floor construction. They are engineered for long spans and are doubled up in places where a wall will be placed over them, and sometimes tripled where heavy roof-loaded support walls are placed above them. They consist of a top and bottom chord/flange made from LVL with a webbing in-between made from oriented strand board (OSB). The webbing can be removed up to certain sizes/shapes according to the manufacturer's or engineer's specifications, but for small holes, wood I-joists come with "knockouts", which are perforated, precut areas where holes can be made easily, typically without engineering approval. When large holes are needed, they can typically be made in the webbing only and only in the center third of the span; the top and bottom chords cannot be cut. Sizes and shapes of the hole, and typically the placing of a hole itself, must be approved by an engineer prior to the cutting of the hole and in many areas, a sheet showing the calculations made by the engineer must be provided to the building inspection authorities before the hole will be approved. Some I-joists are made with W-style webbing like a truss to eliminate cutting and allow ductwork to pass through.# Finger-Jointed Lumber – Solid dimensional lumber lengths typically are limited to lengths of 22 to 24 feet, but can be made longer by the technique of "finger-jointing" lumber by using small solid pieces, usually 18 to 24 inches long, and joining them together using finger joints and glue to produce lengths that can be up to 36 feet long in 2×6 size. Finger-jointing also is predominant in precut wall studs.
- Glu-lam Beams – Created from 2×4 or 2×6 stock by gluing the faces together to create beams such as 4×12 or 6×16. LVL beams have taken their place in most home construction.
- Manufactured Trusses – Trusses are used in home construction as bracing to support the roof rafters in the attic space. It is seen as an easier installation and a better solution for supporting roofs as opposed to the use of dimensional lumber's struts and purlins as bracing. In the southern USA and other parts, stick-framing with dimensional lumber roof support is still predominant. The main drawback of trusses is that less attic space is usable.
- Oriented Strand Board (OSB) – OSB is made by laminating large, thin wood chips with glue, such that the grain orientation of the chips is random, making the OSB panels equally stiff in all directions. OSB has replaced plywood for use as exterior wall sheathing and roof decking (7/16 inch minimum thickness) and in second-story flooring (3/4 inch thickness in a tongue-and-groove interlocking pattern), which is nailed and glued to the I-joists. OSB used in wall sheathing and roof decking will swell if exposed to the elements for even a brief time and must be replaced; therefore, it is covered by a weatherproof membrane such as felt or spun-bonded olefin (Tyvek®) to protect it, secured with plastic cap nails. House wrapping is used on areas which will be sheathed with vinyl siding. 3/4 inch tongue-and-groove OSB flooring is coated to protect it from the elements for a short time until the structure is roofed over. Moisture resistant OSB is often specified for use as a roof underlayment.
Defects in lumberDefects occurring in Timber are grouped into the following five divisions:
Defects due to conversionDuring the process of converting timber to commercial form, the following defects may occur:
- Chip mark
- Diagonal grain
- Torn grain
Defects due to fungiFungi attack timber only when the following two conditions are satisfied simultaneously:
- The moisture content of the timber is above 20%
- There is presence of air and warmth for the growth of fungi.
If any of the above condition is absent, decay of wood due to fungi would not occur. Hence, dry wood due having moisture content less than 20 per cent will remain sound for centuries. Similarly, wood submerged in water will not be attacked by fungi because of absence of air. Following defects are caused in timber by fungi:
- Blue stain
- Brown rot
- Dry rot
- Heart rot
- Sap stain
- Wet rot
- White rot
Defects due to insectsFollowing are the insects which are usually responsible for the decay of timber:
- Marine Borers
Defects due to natural forcesThe main natural forces responsible for causing defects in timber are two, namely, abnormal growth and rupture of tissues.
Defects due to seasoningDefects due to seasoning are the number one cause for splinters and slivers.
- Deck (building)
- Hardwood timber production
- Hartwick Pines State Park
- Illegal logging
- Interlochen State Park
- List of Indian timber trees
- List of woods
- Log scaler
- Lumber baron
- Lumber room
- Lumberman's Monument
- Michigan logging wheels
- Non-timber forest products
- Recycling timber
- Saw pit
- Sodium silicate's use as a timber treatment
- Timber treatment
- United States-Canada softwood lumber dispute
- United Timber Industries
- Woody plant
- Hills Brothers Long Log Harvesting Archive Footage
- Hills Brothers Short Log Harvesting Archive Footage
- National Hardwood Lumber Association
- Timber Development Association of NSW - Australia
- [http://bitterplace.homeip.net:8080/modules.php?name=News&file=article&sid=127 CPSC Test coatings to reduce arsenic emissions from pressure treated wood]
- TRADA: Timber Research And Development Association
- Wood themed links and activities
- Lumber Directory
- The Forest Products Laboratory. US main wood products research lab. Madison, WI (E)
- International Wood Collectors Society
- Xiloteca Manuel Soler (One of the largest private collection of wood samples)
- Humanitarian Timber project (A project to produce and disseminate a field handbook that brings together best practice in the procurement and use of timber in humanitarian emergencies)
timbered in Danish: Tømmer
timbered in German: Bauholz
timbered in Spanish: Madera
timbered in French: Bois (matériau de construction)
timbered in Italian: Legname
timbered in Norwegian: Tømmer
timbered in Norwegian Nynorsk: Tømmer
timbered in Polish: Tarcica
timbered in Portuguese: Madeira
timbered in Russian: Бревно
timbered in Finnish: Puutavara
timbered in Swedish: Timmer