Lumber (American English; used only in North America) or timber (used
in the rest of the English speaking world) is a type of wood that has
been processed into beams and planks, a stage in the process of wood
Lumber is mainly used for structural purposes but has many
other uses as well.
There are two main types of lumber. It may be supplied either
rough-sawn, or surfaced on one or more of its faces. 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; but it is also readily available in
softwoods, such as white pine and red pine, because of their low
Finished lumber is supplied in standard sizes, mostly for the
construction industry – primarily softwood, from coniferous species,
including pine, fir and spruce (collectively spruce-pine-fir), cedar,
and hemlock, but also some hardwood, for high-grade flooring. It is
classified more commonly made from softwood than hardwoods, and 80% of
lumber comes from softwood.
1.1 Remanufactured lumber
1.2 Plastic lumber
2 Conversion of wood logs
3 Dimensional lumber
3.1 Historical Chinese construction
3.2 North American softwoods
3.3 Grades and standards
3.4 North American hardwoods
3.5 Engineered lumber
3.6 Various pieces and cuts
3.7 Timber piles
4 Defects in lumber
4.2 Defects due to fungi and animals
4.3 Natural forces
5 Durability and service life
5.1 Moisture control
5.2 Controlling termites and other insects
6 Ancient construction works
7 Timber framing
8 Environmental effects of lumber
8.1 Residual wood
10 See also
12 Further reading
13 External links
United States milled boards of wood are referred to as lumber.
However, in Britain and other Commonwealth nations, the term timber is
instead used to describe sawn wood products, like floor boards.
United States and Canada, generally timber describes standing
or felled trees. Specifically in Canada, lumber describes cut and
In the United Kingdom, the word lumber is rarely used in relation to
wood and has several other meanings, including unused or unwanted
items. Referring to wood, Timber is almost universally used instead.
See also: Timber recycling
Remanufactured lumber is the result of secondary or tertiary
processing/cutting of previously milled lumber. Specifically, it is
lumber cut for industrial or wood-packaging use.
Lumber is cut by
ripsaw or resaw to create dimensions that are not usually processed by
a primary sawmill.
Resawing is the splitting of 1-inch through 12-inch hardwood or
softwood lumber into two or more thinner pieces of full-length boards.
For example, splitting a ten-foot 2×4 into two ten-foot 1×4s is
Further information: Plastic lumber, Fiber-reinforced composite, and
Structural lumber may also be produced from recycled plastic and new
plastic stock. Its introduction has been strongly opposed by the
forestry industry. Blending fiberglass in plastic lumber enhances
its strength, durability, and fire resistance. Plastic fiberglass
structural lumber can have a "class 1 flame spread rating of 25 or
less, when tested in accordance with
ASTM standard E 84," which means
it burns slower than almost all treated wood lumber.
Conversion of wood logs
Logs are converted into timber by being sawn, hewn, or split. Sawing
with a rip saw is the most common method, because sawing allows logs
of lower quality, with irregular grain and large knots, to be used and
is more economical. There are various types of sawing:
Plain sawn (flat sawn, through and through, bastard sawn) – A log
sawn through without adjusting the position of the log and the grain
runs across the width of the boards.
Quarter sawn and rift sawn – These terms have been confused in
history but generally mean lumber sawn so the annual rings are
reasonably perpendicular to the sides (not edges) of the lumber.
Boxed heart – The pith remains within the piece with some allowance
Heart center – the center core of a log.
Free of heart center (FOHC) – A side-cut timber without any pith.
Free of knots (FOK) – No knots are present.
The examples and perspective in this section deal primarily with North
America and do not represent a worldwide view of the subject. You may
improve this article, discuss the issue on the talk page, or create a
new article, as appropriate. (October 2014) (Learn how and when to
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Dimensional lumber is lumber that is cut to standardized width and
depth, specified in inches. Carpenters extensively use dimensional
lumber in framing wooden buildings. Common sizes include 2×4
(pictured) (also two-by-four and other variants, such as four-by-two
in Australia, New Zealand, and the UK), 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, and twelve feet
in length. In
Canada and the United States, the standard lengths of
lumber are 6, 8, 10, 12, 14, 16, 18, 20, 22 and 24 feet (1.83, 2.44,
3.05, 3.66, 4.27, 4.88, 5.49, 6.10, 6.71 and 7.32 meters). For wall
framing, "stud" or "precut" sizes are available, and are commonly
used. For an eight-, nine-, or ten-foot ceiling height, studs are
available in 92 5⁄8 inches (235 cm), 104 5⁄8 inches
(266 cm), and 116 5⁄8 inches (296 cm). The term
"stud" is used inconsistently to specify length; where the exact
length matters, one must specify the length explicitly.
Historical Chinese construction
Under the prescription of the Method of Construction (營造法式)
issued by the
Southern Song government in the early 12th century,
timbers were standardized to eight cross-sectional dimensions.
Regardless of the actual dimensions of the timber, the ratio between
width and height was maintained at 1:1.5. Units are in Song Dynasty
inches (3.12 cm).
great halls 11 or 9 bays wide
great halls 7 or 5 bays wide
great halls 5 or 3 bays wide or halls 7 or 5 bays wide
great halls 3 bays wide or halls 5 bays wide
great halls 3 small bays wide or halls 3 large bays wide
pagodas and small halls
pagodas and small great halls
small pagodas and ceilings
Timber smaller than the 8th class were called "unclassed" (等外).
The width of a timber is referred to as one "timber" (材), and the
dimensions of other structural components were quoted in multiples of
"timber"; thus, as the width of the actual timber varied, the
dimensions of other components were easily calculated, without
resorting to specific figures for each scale. The dimensions of
timbers in similar application show a gradual diminution from the Sui
Dyansty (580~618) to the modern era; a 1st class timber during the Sui
was reconstructed as 15×10 (Sui Dynasty inches, or 2.94 cm).
North American softwoods
Solid dimensional lumber typically is only available up to lengths of
24 ft (7.32 m).
Engineered wood products, manufactured by
binding the strands, particles, fibers, or veneers of wood, together
with adhesives, to form composite materials, offer more flexibility
and greater structural strength than typical wood building
Pre-cut studs save a framer much time, because they are pre-cut by the
manufacturer for use in 8-, 9-, and 10-ft (2.44, 2.74 and 3.05 m)
ceiling applications, which means the manufacturer has removed a few
inches or centimetres of the piece to allow for the sill plate and the
double top plate with no additional sizing necessary.
In the Americas, two-bys (2×4s, 2×6s, 2×8s, 2×10s, and 2×12s),
named for traditional board thickness in inches, along with the 4×4
(89 mm × 89 mm), are common lumber sizes used in
modern construction. They are the basic building blocks 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.
Lumber's nominal dimensions are larger than the actual standard
dimensions of finished lumber. Historically, the nominal dimensions
were the size of the green (not dried), rough (unfinished) boards that
eventually became smaller finished lumber through drying and planing
(to smooth the wood). Today, the standards specify the final finished
dimensions and the mill cuts the logs to whatever size it needs to
achieve those final dimensions. Typically, that rough cut is smaller
than the nominal dimensions because modern technology makes it
possible and it uses the logs more efficiently. For example, a "2×4"
board historically started out as a green, rough board actually 2 by 4
inches (51 mm × 102 mm). After drying and planing, it
would be smaller, by a nonstandard amount. Today, a "2×4" board
starts out as something smaller than 2 inches by 4 inches and not
specified by standards, and after drying and planing is reliably
1 1⁄2 by 3 1⁄2 inches (38 mm × 89 mm).
North American softwood dimensional lumber sizes
1 × 2
3⁄4 × 1 1⁄2
19 × 38
2 × 2
1 1⁄2 × 1 1⁄2
38 × 38
1 × 3
3⁄4 × 2 1⁄2
19 × 64
2 × 3
1 1⁄2 × 2 1⁄2
38 × 64
1 × 4
3⁄4 × 3 1⁄2
19 × 89
2 × 4
1 1⁄2 × 3 1⁄2
38 × 89
4 × 4
3 1⁄2 × 3 1⁄2
89 × 89
1 × 5
3⁄4 × 4 1⁄2
19 × 114
1 × 6
3⁄4 × 5 1⁄2
19 × 140
2 × 6
1 1⁄2 × 5 1⁄2
38 × 140
4 × 6
3 1⁄2 × 5 1⁄2
89 × 140
6 × 6
5 1⁄2 × 5 1⁄2
140 × 140
1 × 8
3⁄4 × 7 1⁄4
19 × 184
2 × 8
1 1⁄2 × 7 1⁄4
38 × 184
4 × 8
3 1⁄2 × 7 1⁄4
89 × 184
8 × 8
7 1⁄2 × 7 1⁄2
191 × 191
1 × 10
3⁄4 × 9 1⁄4
19 × 235
2 × 10
1 1⁄2 × 9 1⁄4
38 × 235
1 × 12
3⁄4 × 11 1⁄4
19 × 286
2 × 12
1 1⁄2 × 11 1⁄4
38 × 286
Early standards called for green rough lumber to be of full nominal
dimension when dry. However, the dimensions have diminished over time.
In 1910, a typical finished 1-inch (25 mm) board was
13⁄16 in (21 mm). In 1928, that was reduced by 4%, and yet
again by 4% in 1956. In 1961, at a meeting in Scottsdale, Arizona, the
Committee on Grade Simplification and Standardization agreed to what
is now the current U.S. standard: in part, the dressed size of a
1-inch (nominal) board was fixed at 3⁄4 inch; while the
dressed size of 2 inch (nominal) lumber was reduced from
1 5⁄8 inch to the current
1 1⁄2 inch.
Dimensional lumber is available in green, unfinished state, and for
that kind of lumber, the nominal dimensions are the actual dimensions.
Grades and standards
The longest board in the world (2002) is in Poland and measures 36.83
metres (about 120 ft 10 in) long.
Individual pieces of lumber exhibit a wide range in quality and
appearance with respect to knots, slope of grain, shakes and other
natural characteristics. Therefore, they vary considerably in
strength, utility, and value.
The move to set national standards for lumber in the United States
began with publication of the American
Lumber Standard in 1924, which
set specifications for lumber dimensions, grade, and moisture content;
it also developed inspection and accreditation programs. These
standards have changed over the years to meet the changing needs of
manufacturers and distributors, with the goal of keeping lumber
competitive with other construction products. Current standards are
set by the American
Lumber Standard Committee, appointed by the U.S.
Secretary of Commerce.
Design values for most species and grades of visually graded
structural products are determined in accordance with
which consider the effect of strength reducing characteristics, load
duration, safety and other influencing factors. The applicable
standards are based on results of tests conducted in cooperation with
USDA Forest Products Laboratory. Design Values for Wood
Construction, which is a supplement to the ANSI/AF&PA National
Design Specification® for
Wood Construction, provides these lumber
design values, which are recognized by the model building codes.
Canada has grading rules that maintain a standard among mills
manufacturing similar woods to assure customers of uniform quality.
Grades standardize the quality of lumber at different levels and are
based on moisture content, size, and manufacture at the time of
grading, shipping, and unloading by the buyer. The National Lumber
Grades Authority (NLGA) is responsible for writing, interpreting
and maintaining Canadian lumber grading rules and standards. The
Lumber Standards Accreditation Board (CLSAB) monitors the
quality of Canada's lumber grading and identification system.
Attempts to maintain lumber quality over time have been challenged by
historical changes in the timber resources of the
United States –
from the slow-growing virgin forests common over a century ago to the
fast-growing plantations now common in today's commercial forests.
Resulting declines in lumber quality have been of concern to both the
lumber industry and consumers and have caused increased use of
alternative construction products.
Machine stress-rated and machine-evaluated lumber is readily available
for end-uses where high strength is critical, such as trusses,
rafters, laminating stock, I-beams and web joints. Machine grading
measures a characteristic such as stiffness or density that correlates
with the structural properties of interest, such as bending strength.
The result is a more precise understanding of the strength of each
piece of lumber than is possible with visually graded lumber, which
allows designers to use full-design strength and avoid
In Europe, strength grading of rectangular sawn timber (both softwood
and hardwood) is done according to EN-14081  and commonly sorted
into classes defined by EN-338. For softwoods the common classes are
(in increasing strength) C16, C18, C24 and C30. There are also classes
specifically for hardwoods and those in most common use (in increasing
strength) are D24, D30, D40, D50, D60 and D70. For these classes, the
number refers to the required 5th percentile bending strength in
Newtons per square millimetre. There are other strength classes,
including T-classes based on tension intended for use in glulam.
C14, used for scaffolding and formwork
C16 and C24, general construction
C30, prefab roof trusses and where design requires somewhat stronger
joists than C24 can offer. TR26 is also a common trussed rafter
strength class in long standing use in the UK.
C40, usually seen in glulam
Grading rules for African and South American sawn timber have been
developed by ATIBT according to the rules of the Sciages Avivés
Tropicaux Africains (SATA) and is based on clear cuttings –
established by the percentage of the clear surface.
North American hardwoods
In North America, market practices for dimensional lumber made from
hardwoods[a] varies significantly from the regularized standardized
'dimension lumber' sizes used for sales and specification of softwoods
– hardwood boards are often sold totally rough cut,[b] or machine
planed only on the two (broader) face sides. When
Hardwood Boards are
also supplied with planed faces, it is usually both by random widths
of a specified thickness (normally matching milling of softwood
dimensional lumbers) and somewhat random lengths. But besides those
older (traditional and normal) situations, in recent years some
product lines have been widened to also market boards in standard
stock sizes; these usually retail in big box stores and using only a
relatively small set of specified lengths;[c] in all cases hardwoods
are sold to the consumer by the board-foot (144 cubic inches or 2,360
cubic centimetres), whereas that measure is not used for softwoods at
the retailer (to the cognizance of the buyer).[d]
North American hardwood dimensional lumber sizes
Nominal (rough-sawn size)
S1S (surfaced on one side)
S2S (surfaced on two sides)
3⁄8 in (9.5 mm)
5⁄16 in (7.9 mm)
1⁄2 in (13 mm)
7⁄16 in (11 mm)
5⁄8 in (16 mm)
9⁄16 in (14 mm)
1 in or 4⁄4 in
7⁄8 in (22 mm)
13⁄16 in (21 mm)
1 1⁄4 in or 5⁄4 in
1 1⁄8 in (29 mm)
1 1⁄16 in (27 mm)
1 1⁄2 in or 6⁄4 in
1 3⁄8 in (35 mm)
1 5⁄16 in (33 mm)
2 in or 8⁄4 in
1 13⁄16 in (46 mm)
1 3⁄4 inches (44 mm)
3 in or 12⁄4 in
2 13⁄16 in (71 mm)
2 3⁄4 in (70 mm)
4 in or 16⁄4 in
3 13⁄16 in (97 mm)
3 3⁄4 in (95 mm)
Also in North America, hardwood lumber is commonly sold in a "quarter"
system, when referring to thickness; 4/4 (four quarter) refers to a
1-inch-thick (25 mm) board, 8/4 (eight quarter) is a 2-inch-thick
(51 mm) board, etc. This "quarter" system is rarely used for
softwood lumber; although softwood decking is sometimes sold as 5/4,
even though it is actually one-inch thick (from milling 1/8th inch off
each side in a motorized planing step of production). The "quarter"
system of reference is a traditional (cultural) North American lumber
industry nomenclature used specifically to indicate the thickness of
rough sawn hardwood lumber.
The following paragraph is exactly backwards from North American
cultural practices where finished retail and rough lumber share the
same terminology, as is discussed in the paragraph after about
'architects, designers, and builders': In rough sawn lumber it
immediately clarifies that the lumber is not yet milled, avoiding
confusion with milled dimension lumber which is measured as actual
thickness after machining. Examples – 3/4", 19mm, or 1x. In recent
years architects, designers, and builders have begun to use the
"quarter" system in specifications as a vogue of insider knowledge,
though the materials being specified are finished lumber, thus
conflating the separate systems and causing confusion.
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
decreases the value of the timber for furniture.
Main article: Engineered lumber
Engineered lumber is lumber created by a manufacturer and designed for
a certain structural purpose. The main categories of engineered lumber
Laminated veneer lumber
Laminated veneer lumber (LVL) – LVL comes in 1 3⁄4 inch
thicknesses with depths such as 9 1⁄2, 11 7⁄8, 14,
16, 18, and 24 inches, and are often 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 is insufficient, 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 is impractical. This type of lumber is
compromised if it is altered by holes or notches anywhere within the
span or at the ends, 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.
Wooden I-joists – sometimes called "TJI", "Trus Joists" or "BCI",
all of which are brands of wooden 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 aligned over them, and sometimes tripled where heavy
roof-loaded support walls are placed above them. They consist of a top
and bottom chord or flange made from dimensional lumber with a webbing
in-between made from oriented strand board (OSB). The webbing can be
removed up to certain sizes or shapes according to the manufacturer's
or engineer's specifications, but for small holes, wooden I-joists
come with "knockouts", which are perforated, pre-cut 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 lose
their integrity if 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 to
allow ductwork to pass through.
Freshly cut logs showing sap running from beneath bark
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" 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. It is
also an affordable alternative for non-structural hardwood that will
be painted (staining would leave the finger-joints visible). Care is
taken during construction to avoid nailing directly into a glued joint
as stud breakage can occur.
Glulam beams – created from 2×4 or 2×6 stock by gluing the faces
together to create beams such as 4×12 or 6×16. As such, a beam acts
as one larger piece of lumber – thus eliminating the need to harvest
larger, older trees for the same size beam.
Manufactured trusses – trusses are used in home construction as a
pre-fabricated replacement for roof rafters and ceiling joists
(stick-framing). It is seen as an easier installation and a better
solution for supporting roofs than the use of dimensional lumber's
struts and purlins as bracing. In the southern U.S. and elsewhere,
stick-framing with dimensional lumber roof support is still
predominant. The main drawbacks of trusses are reduced attic space,
time required for engineering and ordering, and a cost higher than the
dimensional lumber needed if the same project were conventionally
framed. The advantages are significantly reduced labor costs
(installation is faster than conventional framing), consistency, and
overall schedule savings.
Various pieces and cuts
Further information: Woodworking
Square and rectangular forms: Plank, slat, batten, board, lath,
strapping (typically 3⁄4 in × 1 1⁄2 in), cant (A
partially sawn log such as sawn on two sides or squared to a large
size and later resawn into lumber. A flitch is a type of cant with
wane on one or both sides). Various pieces are also known by their
uses such as post, beam, (girt), stud, rafter, joist, sill plate, wall
Rod forms: pole, (dowel), stick (staff, baton)
In the United States, pilings are mainly cut from southern yellow
pines and Douglas firs. Treated pilings are available in Chromated
copper arsenate retentions of 0.60, 0.80 and 2.50 pounds per cubic
foot (9.6, 12.8 and 40.0 kg/m3) if treatment is required.
Defects in lumber
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Defects occurring in lumber are grouped into the following four
During the process of converting timber to commercial form the
following defects may occur:
Chip mark: this defect is indicated by the marks or signs placed by
chips on the finished surface of timber
Diagonal grain: improper sawing of timber
Torn grain: when a small depression is made on the finished surface
due to falling of some tool
Wane: presence of original rounded surface in the finished product
Defects due to fungi and animals
Fungi attack timber when these conditions are all present:
The timber moisture content is above 25% on a dry-weight basis
The environment is sufficiently warm
Oxygen (O2) is present
Wood with less than 25% moisture (dry weight basis) can remain free of
decay for centuries. Similarly, wood submerged in water may not be
attacked by fungi if the amount of oxygen is inadequate.
Fungi timber defects:
Following are the insects and molluscs which are usually responsible
for the decay of timber:
Marine borers (Barnea similis)
Teredos (Teredo navalis)
Main article: wood warping
There are two main natural forces responsible for causing defects in
timber: abnormal growth and rupture of tissues. Rupture of tissue
includes cracks or splits in the wood called "shakes". "Ring shake",
"wind shake", or "ring failure" is when the wood grain separates
around the growth rings either while standing or during felling.
Shakes may reduce the strength of a timber and the appearance thus
reduce lumber grade and may capture moisture, promoting decay. Eastern
hemlock is known for having ring shake. A "check" is a crack on
the surface of the wood caused by the outside of a timber shrinking as
it seasons. Checks may extend to the pith and follow the grain. Like
shakes, checks can hold water promoting rot. A "split" goes all the
way through a timber. Checks and splits occur more frequently at the
ends of lumber because of the more rapid drying in these
The seasoning of lumber is typically either kiln- or air-dried.
Defects due to seasoning are the main cause of splits, bowing and
Durability and service life
Under proper conditions, wood provides excellent, lasting performance.
However, it also faces several potential threats to service life,
including fungal activity and insect damage – which can be avoided
in numerous ways. Section 2304.11 of the International Building Code
addresses protection against decay and termites. This section provides
requirements for non-residential construction applications, such as
wood used above ground (e.g., for framing, decks, stairs, etc.), as
well as other applications.
There are four recommended methods to protect wood-frame structures
against durability hazards and thus provide maximum service life for
the building. All require proper design and construction:
Controlling moisture using design techniques to avoid decay
Providing effective control of termites and other insects
Using durable materials such as pressure treated or naturally durable
species of wood where appropriate
Providing quality assurance during design and construction and
throughout the building’s service life using appropriate maintenance
Wood is a hygroscopic material, which means it naturally absorbs and
releases water to balance its internal moisture content with the
surrounding environment. The moisture content of wood is measured by
the weight of water as a percentage of the oven-dry weight of the wood
fiber. The key to controlling decay is controlling moisture. Once
decay fungi are established, the minimum moisture content for decay to
propagate is 22 to 24 percent, so building experts recommend 19
percent as the maximum safe moisture content for untreated wood in
service. Water by itself does not harm the wood, but rather, wood with
consistently high moisture content enables fungal organisms to grow.
The primary objective when addressing moisture loads is to keep water
from entering the building envelope in the first place, and to balance
the moisture content within the building itself. Moisture control by
means of accepted design and construction details is a simple and
practical method of protecting a wood-frame building against decay.
For applications with a high risk of staying wet, designers specify
durable materials such as naturally decay-resistant species or wood
that has been treated with preservatives. Cladding, shingles, sill
plates and exposed timbers or glulam beams are examples of potential
applications for treated wood.
Controlling termites and other insects
For buildings in termite zones, basic protection practices addressed
in current building codes include (but are not limited to) the
• Grading the building site away from the foundation to provide
• Covering exposed ground in any crawl spaces with 6-mil
polyethylene film and maintaining at least 12 to 18 inches (300 to
460 mm) of clearance between the ground and the bottom of framing
members above (12 inches to beams or girders, 18 inches to
joists or plank flooring members)
• Supporting post columns by concrete piers so that there is at
least 6 inches (150 mm) of clear space between the wood and
• Installing wood framing and sheathing in exterior walls at least
eight inches above exposed earth; locating siding at least six inches
from the finished grade
• Where appropriate, ventilating crawl spaces according to local
• Removing building material scraps from the job site before
• If allowed by local regulation, treating the soil around the
foundation with an approved termiticide to provide protection against
Special fasteners are used with treated lumber because of the
corrosive chemicals used in its preservation process.
To avoid decay and termite infestation, untreated wood is separated
from the ground and other sources of moisture. These separations are
required by many building codes and are considered necessary to
maintain wood elements in permanent structures at a safe moisture
content for decay protection. When it is not possible to separate wood
from the sources of moisture, designers often rely on
Wood can be treated with a preservative that improves service life
under severe conditions without altering its basic characteristics. It
can also be pressure-impregnated with fire-retardant chemicals that
improve its performance in a fire. One of the early treatments to
"fireproof lumber", which retard fires, was developed in 1936 by the
Protexol Corporation, in which lumber is heavily treated with
Wood does not deteriorate simply because it gets wet. When
wood breaks down, it is because an organism is eating it.
Preservatives work by making the food source inedible to these
organisms. Properly preservative-treated wood can have 5 to 10 times
the service life of untreated wood. Preserved wood is used most often
for railroad ties, utility poles, marine piles, decks, fences and
other outdoor applications. Various treatment methods and types of
chemicals are available, depending on the attributes required in the
particular application and the level of protection needed.
There are two basic methods of treating: with and without pressure.
Non-pressure methods are the application of preservative by brushing,
spraying or dipping the piece to be treated. Deeper, more thorough
penetration is achieved by driving the preservative into the wood
cells with pressure. Various combinations of pressure and vacuum are
used to force adequate levels of chemical into the wood.
Pressure-treating preservatives consist of chemicals carried in a
solvent. Chromated copper arsenate, once the most commonly used wood
preservative in North America began being phased out of most
residential applications in 2004. Replacing it are amine copper quat
and copper azole.
All wood preservatives used in the
United States and
registered and regularly re-examined for safety by the U.S.
Environmental Protection Agency and Health Canada's Pest Management
and Regulatory Agency, respectively.
Ancient construction works
Timber was used as a dominant building material in most of the ancient
Kerala and coastal
Karnataka of India.
Main article: Timber framing
Timber framing is a style of construction which uses heavier framing
elements than modern stick framing, which uses dimensional lumber. The
timbers originally were tree boles squared with a broadaxe or adze and
joined together with joinery without nails. Modern timber framing has
been growing in popularity in the
United States since the 1970s.
Environmental effects of lumber
Green building minimizes the impact or "environmental footprint" of a
Wood is a major building material that is renewable and
replenishable in a continuous cycle. Studies show manufacturing
wood uses less energy and results in less air and water pollution than
steel and concrete. However, demand for lumber is blamed for
The conversion from coal to biomass power is a growing trend in the
The United Kingdom, Uzbekistan, Kazakhstan, Australia, Fiji,
Madagascar, Mongolia, Russia, Denmark, Switzerland and Swaziland
governments all support an increased role for energy derived from
biomass, which are organic materials available on a renewable basis
and include residues and/or byproducts of the logging, sawmilling and
papermaking processes. In particular, they view it as a way to lower
greenhouse gas emissions by reducing consumption of oil and gas while
supporting the growth of forestry, agriculture and rural economies.
Studies by the U.S. government have found the country’s combined
forest and agriculture land resources have the power to sustainably
supply more than one-third of its current petroleum consumption.
Biomass is already an important source of energy for the North
American forest products industry. It is common for companies to have
cogeneration facilities, also known as combined heat and power, which
convert some of the biomass that results from wood and paper
manufacturing to electrical and thermal energy in the form of steam.
The electricity is used to, among other things, dry lumber and supply
heat to the dryers used in paper-making.
^ Because working expensive hardwoods is far more difficult and
costly, and because an odd width might well be conserved and be of use
in making such surfaces as a cabinet side or table top joined from
many smaller widths, the industry generally only does minimal
processing, preserving as much board width as is practicable. This
leaves culling and width decisions totally in the hands of the
craftsman building cabinets or furniture with the boards.
^ In quarter sawn thicknesses, meaning the thickness and width
dimensions as they come out of the sawmills table. Because lengths
vary most with temperature, hardwoods boards in the US often have a
bit of extra length.
^ small set of specified lengths: Fixed length hardwood boards in the
United States are most common in 4–6' lengths, with a good
representation of 8' lengths in a variety of widths, and a few widths
with occasional dimensional sizes to 12' lengths. Often the longer
sizes would need be special ordered.
^ Fixed board lengths not apply in all countries; for example, in
Australia and the United States, many hardwood boards are sold to
timber yards in packs with a common width profile (dimensions) but not
necessarily consisting of boards of identical lengths.
Hardwood timber production
List of woods
Non-timber forest product
Pine Cost Estimates". patscolor.com.
Softwood – Difference and Comparison". Diffen.
^ "Conceptual Reference Database for Building Envelope Research".
Archived from the original on 2008-02-23. Retrieved 2008-03-28.
^ "Recycling and Deregulation: Opportunities for Market Development"
Resource Recycling, September 1996
ASTM D6108 – 09 Standard Test Method for Compressive Properties
Lumber and Shapes"
ASTM Committee D20.20 on Plastic Lumber
^ "SAFPLANK Interlocking Decking System" Archived 2013-04-26 at the
Wayback Machine. Strongwell.com
^ 李, 誡 (1103). 營造法式. China: Song Government. Retrieved May
^ 王, 貴祥.
中國建築史論匯刊. 3: 116.
^ "Naturally:wood". Archived from the original on 2016-05-22.
^ Smith, L. W. and L. W.
Wood (1964). "History of yard lumber size
USDA Forest Service, Forest Product
Lumber Standard Committee: History". www.alsc.org.
^ "Structural Properties and Performance" (PDF). woodworks.org.
WoodWorks. Retrieved May 7, 2017.
Lumber Grades Authority (Canada)". Archived from the
original on 2011-08-11.
^ "CLSAB and
Lumber Grading Quality". www.clsab.ca. Canadian Lumber
Standards Accreditation Board.
^ "Minimizing the use of lumber products in residential construction".
www.neo.ne.gov. Nebraska Energy Office.
^ "Material substitution in the U.S. residential construction
industry" (PDF). University of Washington, School of Forest Resources.
Archived from the original (PDF) on 2010-06-20.
^ "Naturally:wood". Archived from the original on 2016-05-22.
^ Ridley-Ellis, Dan; Stapel, Peter; Baño, Vanesa (1 May 2016).
"Strength grading of sawn timber in Europe: an explanation for
engineers and researchers". European Journal of
Wood and Wood
Products. 74 (3): 291–306. doi:10.1007/s00107-016-1034-1 – via
^ "What is TR26?". Centre for
Wood Science & Technology. 1
^ "African and South American sawn timber". www.fordaq.com. Fordaq
S.A., The Timber Network. Retrieved May 7, 2017.
^ "Austin Energy page describing engineered structural lumber".
Archived from the original on 2006-08-22. Retrieved 2006-09-10.
^ a b U. S. Department of Agriculture. "Shake", The Encyclopedia of
Wood. New York: Skyhorse Pub., 2007. Print.
^ karenkoenig (2016-04-04). "Understanding & working with wood
Woodworking Network. Retrieved 2018-03-12.
^ "WoodWorks Durability and Service Life" (PDF).
Wood That Fights." Popular Sciences, March 1944, p. 59.
Lumber is Made Fireproof by Salt Treatment" Popular Mechanics,
April 1936 bottom-left p. 560
^ a b c "About Treated Wood". CWC. Retrieved May 7, 2017.
^ ALAYAM : The Hindu Temple;An Epitome of Hindu Culture;
G.Venkataramana Reddy; Published by Adhyaksha; Sri Ramakrishna Math;
ISBN 978-81-7823-542-4, p. 32
^ Roy, Robert L..
Timber framing for the rest of us. Gabriola Island,
BC: New Society Publishers, 2004. 6. Print. ISBN 0865715084
^ Lippke, B., E. Oneil, R. Harrison, K. Skog, L. Gustavsson, and R.
Sathre. 2011. Life cycle impacts of forest management and wood
utilization on carbon mitigation: knowns and unknowns. Carbon
Management 2(3): 303–33. Archived 2011-11-10 at the Wayback Machine.
Peter Dauvergne and Jane Lister, Timber Archived 2016-05-22 at the
Portuguese Web Archive (Polity Press, 2011).
^ "EERE News: EERE Network News".
^ U.S. Department of Agriculture, U.S. Department of Energy
a Feedstock for a Bioenergy and Bioproducts Industry: The Technical
Feasibility of a Billion-Ton Annual Supply, 2005 Executive Summary
Archived 2008-08-25 at the Wayback Machine.
Sathre, R; O'Conner, J (2010). A Synthesis of Research on Wood
Products and Greenhouse Gas Impacts (PDF) (2 ed.). FPInnovations.
ISBN 978-0-86488-546-3. Archived from the original (PDF) on
Look up lumber or timber in Wiktionary, the free dictionary.
Wikimedia Commons has media related to Timber.
Lumber Association (Rules for Grading Hardwood
Lumber – Inspector Training School)
Timber Development Association of NSW – Australia
TDA: Timber Decking Association – UK
TRADA: Timber Research And Development Association
The Forest Products Laboratory. U.S. main wood products research lab.
Madison, WI (E)
WCTE, World Conference on Timber Engineering June 20–24, 2010,
Riva del Garda, Trentino, Italy
Forest Products data in
Canada since 1990
Glued laminated timber
Oriented strand board
Oriented structural straw board
Structural insulated panel
Ramial chipped wood
List of woods
Non-timber forest products
Bow and arrow
Cedar (Calocedrus, Cedrus)
Linden (lime, basswood)
Crown of thorns
Mortise and tenon
Tongue and groove
American Association of Woodturners
Architectural Woodwork Institute
Wood Workers' International
Caricature Carvers of America
International Federation of Building and
Wood Carvers Association
Timber Framers Guild
Frame and panel