View source for Lumber

{{Short description|Wood that has been processed into beams and planks}}
{{Other uses|Lumber (disambiguation)}}
{{Redirect|Timber|other uses|Timber (disambiguation)}}
{{Use dmy dates|date=July 2022}}
[[File:Wood from victoria mountain ash.jpg|thumb|upright=1.15|Wood cut from Victorian ''[[Eucalyptus regnans]]'']]
[[File:Bellingham, Washington, harbor, filled with logs, 1972.jpg|thumb|upright=1.15|The harbor of Bellingham, Washington, filled with logs, 1972]]

'''Lumber''', also called '''timber''' in the United Kingdom, Australia, and New Zealand, is [[wood]] that has been [[carpentry|processed]] into uniform and useful sizes (dimensional lumber), including [[beam (structure)|beams]] and [[plank (wood)|planks or boards]]. Lumber is mainly used for [[framing (construction)|construction framing]], as well as finishing (floors, [[wall panel]]s, [[window frame]]s). Lumber has many uses beyond home building. In some parts of the world, including the United States and Canada, the term ''timber'' refers specifically to unprocessed [[wood fiber]], such as cut logs or standing trees that have yet to be cut.

Lumber may be supplied either rough-[[sawmill|sawn]], or surfaced on one or more of its faces. ''Rough lumber'' is the raw material for furniture-making, and manufacture of other items requiring cutting and shaping. It is available in many species, including [[hardwood]]s and [[softwood]]s, such as [[Pinus classification|white pine]] and [[red pine]], because of their low cost.<ref>{{cite web|title=Southern Pine Cost Estimates|url=http://patscolor.com/materials/timber/the-southern-yellow-pine-flooring-decking-guide/|website=patscolor.com}}</ref>

''Finished lumber'' is supplied in standard sizes, mostly for the construction industry – primarily [[softwood]], from [[conifer]]ous species, including [[pine]], [[fir]] and [[spruce]] (collectively [[spruce-pine-fir]]), [[Cedrus|cedar]], and [[Tsuga|hemlock]], but also some hardwood, for high-grade flooring. It is more commonly made from softwood than hardwoods, and 80% of lumber comes from softwood.<ref>{{cite web|url=http://www.diffen.com/difference/Hardwood_vs_Softwood|title=Hardwood vs Softwood – Difference and Comparison |publisher=Diffen}}</ref>

==Terminology==
In the United States and Canada, milled boards are called ''lumber'', while ''timber'' describes standing or felled trees.<ref name="CRD">{{cite web|title=Conceptual Reference Database for Building Envelope Research|url=http://alcor.concordia.ca/~raojw/crd/concept/concept000069.html|access-date=2008-03-28|url-status=dead|archive-url=https://web.archive.org/web/20080223221704/http://alcor.concordia.ca/~raojw/crd/concept/concept000069.html|archive-date=2008-02-23}}</ref>

In contrast, in Britain, and some other Commonwealth nations and Ireland, the term ''[[wikt: timber|timber]]'' is used in both senses. (In the UK, the word ''lumber'' is rarely used in relation to wood and has several other meanings.)

===Re-manufactured lumber===
{{See also|Timber recycling}}
Re-manufactured lumber is the result of secondary or tertiary processing of previously milled lumber. Specifically, it refers to 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]].

Re-sawing is the splitting of {{convert|1|to(-)|12|in|adj=on}} [[hardwood]] or [[softwood]] lumber into two or more thinner pieces of full-length boards. For example, splitting a {{convert|10|ft||adj=mid|-long}} 2×4 ({{cvt|1+1/2|by|3+1/2|in|disp=or}}) into two 2×2s ({{cvt|1+1/2|by|1+1/2|in|disp=or}}) of the same length is considered re-sawing.

===Plastic lumber===
{{Further|Plastic lumber|Fiber-reinforced composite|Wood-plastic composite}}
Structural lumber may also be produced from recycled plastic and new plastic stock. Its introduction has been strongly opposed by the [[forestry]] industry.<ref>[http://www.volokh.com/sasha/resrec.html "Recycling and Deregulation: Opportunities for Market Development"] ''Resource Recycling,'' September 1996</ref> Blending fiberglass in plastic lumber enhances its strength, durability, and fire resistance.<ref>[http://www.astm.org/COMMIT/SUBCOMMIT/D2020.htm "ASTM D6108 – 09 Standard Test Method for Compressive Properties of Plastic Lumber and Shapes"] ''ASTM Committee D20.20 on Plastic Lumber''</ref> 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 more slowly than almost all treated wood lumber.<ref>[http://www.strongwell.com/PDFfiles/Safdeck%20Safplank/SAFPLANK%20SAFDECK%20Fiberglass%20Decking%20Systems%20Brochure.pdf "SAFPLANK Interlocking Decking System"] {{webarchive|url=https://web.archive.org/web/20130426205658/http://www.strongwell.com/PDFfiles/Safdeck%20Safplank/SAFPLANK%20SAFDECK%20Fiberglass%20Decking%20Systems%20Brochure.pdf |date=2013-04-26 }} ''Strongwell.com''</ref>

=== Timber mark ===
A timber mark is a code beaten on to cut wood by a specially made hammer to show the logging licence.<ref>{{Cite web |date=2024-09-06 |title=Drax, subsidies, greenwashing and dodgy accounting |url=https://redgreenlabour.org/2024/09/06/drax-subsidies-greenwashing-and-dodgy-accounting/ |access-date=2024-10-03 |website=Red Green Labour |language=en-US}}</ref>

==History==
The definition of the word ''lumber'' as sawn planks of wood originated in the 17th century in North America.<ref>{{cite web | url=https://www.merriam-webster.com/words-at-play/lumber-word-history-lombard | title=The Strange Story of 'Lumber' }}</ref>

In 1420, the archipelago of [[Madeira]] was colonized by the [[Portuguese Empire]]. [[Prince Henry the Navigator]] sent settlers to Madeira, who cleared the huge expanses of forest to grow crops. The felled trees were processed at sawmills and shipped to the mainland.<ref>{{cite web |last1=Cartwright |first1=Mark |title=The Portuguese Colonization of Madeira |url=https://www.worldhistory.org/article/1756/the-portuguese-colonization-of-madeira/ |website=World History Encyclopedia |date=21 May 2021 |access-date=14 November 2023 |language=en}}</ref>

[[Cornelis Corneliszoon van Uitgeest|Cornelis Corneliszoon]] (or Krelis Lootjes) was a Dutch windmill owner from [[Uitgeest]] who invented the first wind-powered sawmill in 1593. This made the conversion of logs into planks thirty times faster than previous manually operated sawmills.<ref>{{cite web | url=https://www.core77.com/posts/53123/A-Brief-History-of-Wood-Splitting-Technology-Part-3-The-Wind-Powered-Sawmill-That-Changed-Dutch-History | title=A Brief History of Wood-Splitting Technology, Part 3: The Wind-Powered Sawmill That Changed Dutch History }}</ref><ref name="Dehoop">[http://www.dehoopuitgeest.nl/engels/corneliszoonuk.html "Cornelis Corneliszoon van Uitgeest (1550–1607), inventor of the wind powered saw mill", Industrial Heritage Park ''De Hoop''] {{webarchive|url=https://web.archive.org/web/20061006214829/http://www.dehoopuitgeest.nl/engels/corneliszoonuk.html |date=2006-10-06 }}</ref>

==Conversion of wood logs==
[[File:L' usine de transformation de bois Kotkamills Oy à Kotka.jpg|thumb|A [[sawmill]] with the [[Log driving|floating logs]] in [[Kotka]], [[Finland]]]]
Logs are ''converted'' into lumber by being sawn, [[Hewing|hewn]], or [[Wood splitting|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 sawing|Quarter sawn]] and [[Rift sawing|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 timber, post or beam, with some allowance for exposure.
* Heart center – the center core of a log.
* Free of heart center (FOHC) – A side-cut timber, post or beam without any pith.
* Free of knots (FOK) – No knots are present.

==Dimensional lumber==
{{globalize|section|North America|date=August 2025}}
[[File:2 By 4 Clue Stick.jpg|thumb|A common {{convert|2|by|4|inch|mm|round=5|order=flip|abbr=in|adj=on}} board]]

Dimensional lumber is lumber that is cut to standardized width and depth, often specified in millimetres or inches (but see below for information on nominal dimensions vs. actual dimensions). [[Carpentry|Carpenters]] extensively use dimensional lumber in [[Framing (construction)|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 {{convert|6|,|8|,|10|,|12|,|14|,|16|,|18|,|20|,|22|and|24|ft|m}}. For wall framing, precut "stud" lengths are available, and are commonly used. For ceilings heights of {{convert|8|,|9|or|10|ft|m}}, [[Wall stud|studs]] are available in {{convert|92+5/8|in|m}}, {{convert|104+5/8|in|m}}, and {{convert|116+5/8|in|m}}.{{citation needed|date=August 2020}}

===North American softwoods===
The length of a unit of dimensional lumber is limited by the height and [[wikt:girth|girth]] of the tree it is milled from. In general the maximum length is {{convert|24|ft|m|2|abbr=on}}. 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 materials.<ref>{{cite web|url=http://www.naturallywood.com/Build-and-Design/Wood-Applications/Engineered-Wood-Products.aspx|title=Naturally:wood|url-status=dead|archive-url=http://arquivo.pt/wayback/20160522030232/http://www.naturallywood.com/Build-and-Design/Wood-Applications/Engineered-Wood-Products.aspx|archive-date=2016-05-22}}</ref>

Pre-cut studs save a framer much time, because they are pre-cut by the manufacturer for use in 8-, 9-, and 10-foot 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 ({{convert|3.5|×|3.5|in|mm|0|disp=out}}), are common lumber sizes used in modern construction. They are the basic building blocks for such common structures as [[balloon framing|balloon-frame]] or [[platform framing|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 [[Real versus nominal value#Engineering|''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 to use the logs more efficiently. For example, a "2×4" board historically started out as a green, rough board actually {{convert|2|×|4|in}}. 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 minimally {{convert|1+1/2|×|3+1/2|in}}.<ref>{{cite web|url=https://roofonline.com/american-softwood-lumber-standard|title=American Softwood Lumber Standard|website=Roof Online|language=en-US|access-date=2018-07-27}}</ref>

{|class="wikitable" style="clear:both; text-align:center"
|+North American softwood dimensional lumber sizes
|-
! Nominal
! style="border-right-style:solid; border-right-width:3px;" colspan=2 | Actual
! Nominal
! style="border-right-style:solid; border-right-width:3px;" colspan=2 | Actual
! Nominal
! style="border-right-style:solid; border-right-width:3px;" colspan=2 | Actual
! Nominal
! style="border-right-style:solid; border-right-width:3px;" colspan=2 | Actual
! Nominal
! colspan=2 | Actual

|-
! inches
! inches
! style="border-right-style:solid; border-right-width:3px;" | mm
! inches
! inches
! style="border-right-style:solid; border-right-width:3px;" | mm
! inches
! inches
! style="border-right-style:solid; border-right-width:3px;" | mm
! inches
! inches
! style="border-right-style:solid; border-right-width:3px;" | mm
! inches
! inches
! mm

|-
| '''1&nbsp;×&nbsp;2'''
| {{frac|3|4}}&nbsp;×&nbsp;{{frac|1|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 19&nbsp;×&nbsp;38
| '''2&nbsp;×&nbsp;2'''
| {{frac|1|1|2}}&nbsp;×&nbsp;{{frac|1|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 38&nbsp;×&nbsp;38
| colspan="3" rowspan="2" style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan="3" rowspan="4" style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan="3" rowspan="5" | &nbsp;

|-
| '''1&nbsp;×&nbsp;3'''
| {{frac|3|4}}&nbsp;×&nbsp;{{frac|2|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 19&nbsp;×&nbsp;64
| '''2&nbsp;×&nbsp;3'''
| {{frac|1|1|2}}&nbsp;×&nbsp;{{frac|2|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 38&nbsp;×&nbsp;64

|-
| '''1&nbsp;×&nbsp;4'''
| {{frac|3|4}}&nbsp;×&nbsp;{{frac|3|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 19&nbsp;×&nbsp;89
| '''2&nbsp;×&nbsp;4'''
| {{frac|1|1|2}}&nbsp;×&nbsp;{{frac|3|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 38&nbsp;×&nbsp;89
| '''4&nbsp;×&nbsp;4'''
| {{frac|3|1|2}}&nbsp;×&nbsp;{{frac|3|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 89&nbsp;×&nbsp;89

|-
| '''1&nbsp;×&nbsp;5'''
| {{frac|3|4}}&nbsp;×&nbsp;{{frac|4|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 19&nbsp;×&nbsp;114
| colspan=3 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 style="border-right-style:solid; border-right-width:3px;" | &nbsp;

|-
| '''1&nbsp;×&nbsp;6'''
| {{frac|3|4}}&nbsp;×&nbsp;{{frac|5|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 19&nbsp;×&nbsp;140
| '''2&nbsp;×&nbsp;6'''
| {{frac|1|1|2}}&nbsp;×&nbsp;{{frac|5|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 38&nbsp;×&nbsp;140
| '''4&nbsp;×&nbsp;6'''
| {{frac|3|1|2}}&nbsp;×&nbsp;{{frac|5|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 89&nbsp;×&nbsp;140
| '''6&nbsp;×&nbsp;6'''
| {{frac|5|1|2}}&nbsp;×&nbsp;{{frac|5|1|2}}
| style="border-right-style:solid; border-right-width:3px;" | 140&nbsp;×&nbsp;140

|-
| '''1&nbsp;×&nbsp;8'''
| {{frac|3|4}}&nbsp;×&nbsp;{{frac|7|1|4}}
| style="border-right-style:solid; border-right-width:3px;" | 19&nbsp;×&nbsp;184
| '''2&nbsp;×&nbsp;8'''
| {{frac|1|1|2}}&nbsp;×&nbsp;{{frac|7|1|4}}
| style="border-right-style:solid; border-right-width:3px;" | 38&nbsp;×&nbsp;184
| '''4&nbsp;×&nbsp;8'''
| {{frac|3|1|2}}&nbsp;×&nbsp;{{frac|7|1|4}}
| style="border-right-style:solid; border-right-width:3px;" | 89&nbsp;×&nbsp;184
| colspan="3" rowspan="3" style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| '''8&nbsp;×&nbsp;8'''
| {{frac|7|1|2}}&nbsp;×&nbsp;{{frac|7|1|2}}
| 191&nbsp;×&nbsp;191

|-
| '''1&nbsp;×&nbsp;10'''
| {{frac|3|4}}&nbsp;×&nbsp;{{frac|9|1|4}}
| style="border-right-style:solid; border-right-width:3px;" | 19&nbsp;×&nbsp;235
| '''2&nbsp;×&nbsp;10'''
| {{frac|1|1|2}}&nbsp;×&nbsp;{{frac|9|1|4}}
| style="border-right-style:solid; border-right-width:3px;" | 38&nbsp;×&nbsp;235
| colspan="3" rowspan="2" style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan="3" rowspan="2" | &nbsp;

|-
| '''1&nbsp;×&nbsp;12'''
| {{frac|3|4}}&nbsp;×&nbsp;{{frac|11|1|4}}
| style="border-right-style:solid; border-right-width:3px;" | 19&nbsp;×&nbsp;286
| '''2&nbsp;×&nbsp;12'''
| {{frac|1|1|2}}&nbsp;×&nbsp;{{frac|11|1|4}}
| style="border-right-style:solid; border-right-width:3px;" | 38&nbsp;×&nbsp;286
|}

As previously noted, less wood is needed to produce a given finished size than when standards called for the green lumber to be the full nominal dimension. However, even the dimensions for finished lumber of a given nominal size have changed over time. In 1910, a typical finished {{convert|1|in|mm|adj=on}} board was {{convert|13/16|in|mm|abbr=on}}. In 1928, that was reduced by 4%, and yet again by 4% in 1956. In 1961, 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 {{frac|3|4}}&nbsp;inch; while the dressed size of 2&nbsp;inch (nominal) lumber was ''reduced'' from {{frac|1|5|8}}&nbsp;inch to the current {{frac|1|1|2}}&nbsp;inch.<ref>{{cite web|url=http://www.fpl.fs.fed.us/documnts/misc/miscpub_6409.pdf|author=Smith, L. W. and L. W. Wood|date=1964|title=History of yard lumber size standards|publisher=USDA Forest Service, Forest Product Laboratory}}</ref>

In 1964, [[Popular Mechanics]] magazine hired an independent agency to test the comparative strength of multiple samples of (A) a full-size 2×4 inches, (B) {{frac|1|5|8}}×{{frac|3|5|8}} inches, (C) {{frac|1|5|8}}×{{frac|3|1|2}} inches, and (D) {{frac|1|1|2}}×{{frac|3|1|2}} inches (today’s standard). With A’s compressive strength benchmarked as “100%,” B-C-D were 90.7%, 82.2%, and 73.6% the strength of A’s full-size 2×4. Stated another way, the 1960s’ reduction of the smaller dimension from {{frac|1|5|8}} to {{frac|1|1|2}} inches reduced compressive strength by 10.46%.<ref>Mikesell, Arthur. “They May Trim the 2×4 Some More.” Popular Mechanics 121:1 (January 1964), 113-115.</ref> 

Dimensional lumber is available in green, unfinished state, and for that kind of lumber, the nominal dimensions are the actual dimensions.

=== Grades and standards ===
{{main|Timber grading}}
<!-- most of this chapter should be moved into the main article, to shorten this very long article -->
[[File:The longest board in the world (2002).jpg|thumb|The longest plank in the world (2002) is in Poland (near [[Szymbark, Pomeranian Voivodeship|Szymbark]]) 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 the 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 [[United States Secretary of Commerce|U.S. Secretary of Commerce]].<ref>{{cite web|url=http://www.alsc.org/geninfo_history_mod.htm|title=American Lumber Standard Committee: History|website=www.alsc.org}}</ref>

Design values for most species and grades of visually graded structural products are determined in accordance with [[ASTM]] standards, 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 the [[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.<ref name="WoodWorks Structural Properties and Performance">{{cite web|title=Structural Properties and Performance|url=http://www.woodworks.org/wp-content/uploads/Wood-design-structural-properties-performance-fact-sheet.pdf|website=woodworks.org|publisher=WoodWorks|access-date=7 May 2017|archive-date=26 March 2020|archive-url=https://web.archive.org/web/20200326010734/https://www.woodworks.org/wp-content/uploads/Wood-design-structural-properties-performance-fact-sheet.pdf|url-status=dead}}</ref>

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)<ref>{{cite web|url=http://www.nlga.org/app/dynarea/view_article/1.html|title=National Lumber Grades Authority (Canada)|url-status=dead|archive-url=https://web.archive.org/web/20110811113224/http://www.nlga.org/app/dynarea/view_article/1.html|archive-date=2011-08-11}}</ref> is responsible for writing, interpreting and maintaining Canadian lumber grading rules and standards. The Canadian Lumber Standards Accreditation Board (CLSAB)<ref>{{cite web|url=http://www.clsab.ca/|title=CLSAB and Lumber Grading Quality |publisher= Canadian Lumber Standards Accreditation Board|website=www.clsab.ca}}</ref> monitors the quality of Canada's lumber grading and identification system. Their common grade abbrievation, CLS, [[Canadian Lumber Standard]] is well utilised in the construction industry.<ref name="Homebuilding">{{cite web | last=Jenkins | first=Steve | title=What is CLS timber and what DIY projects is it good for? | website=Homebuilding & Renovating | date=2023-09-03 | url=https://www.homebuilding.co.uk/advice/what-is-cls-timber | access-date=2024-08-22}}</ref>

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 forest]]s common over a century ago to the fast-growing [[Forest#Forest plantations|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.<ref>{{cite web|url=http://www.neo.ne.gov/home_const/factsheets/min_use_lumber.htm|title=Minimizing the use of lumber products in residential construction|publisher=Nebraska Energy Office|website=www.neo.ne.gov|access-date=2009-08-26|archive-url=https://web.archive.org/web/20170320140257/http://www.neo.ne.gov/home_const/factsheets/min_use_lumber.htm|archive-date=2017-03-20|url-status=dead}}</ref><ref>{{cite web|url=http://www.cfr.washington.edu/Research/factSheets/11-CINTRAmatsubstitute.pdf|title=Material substitution in the U.S. residential construction industry|publisher=[[University of Washington]], School of Forest Resources|url-status=dead|archive-url=https://web.archive.org/web/20100620142144/http://www.cfr.washington.edu/research/factSheets/11-CINTRAmatsubstitute.pdf|archive-date=2010-06-20}}</ref>

Machine stress-rated and machine-evaluated lumber are readily available for end-uses where high strength is critical, such as [[truss]]es, [[rafter]]s, laminating stock, [[I-joist|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 overbuilding.<ref>{{cite web|url=http://naturallywood.com/Wood-Products/Wood-Performance/Grades-and-Quality.aspx|title=Naturally:wood|url-status=dead|archive-url=http://arquivo.pt/wayback/20160522205856/http://naturallywood.com/Wood-Products/Wood-Performance/Grades-and-Quality.aspx|archive-date=2016-05-22}}</ref>

In Europe, strength grading of rectangular sawn lumber/timber (both softwood and hardwood) is done according to EN-14081<ref>{{cite journal|title=Strength grading of sawn lumber/timber in Europe: an explanation for engineers and researchers|first1=Dan|last1=Ridley-Ellis|first2=Peter|last2=Stapel|first3=Vanesa|last3=Baño|s2cid=18860384|date=1 May 2016|journal=European Journal of Wood and Wood Products|volume=74|issue=3|pages=291–306|doi=10.1007/s00107-016-1034-1|url=https://napier-surface.worktribe.com/169717/1/EJWP%20ridleyellis%20et%20al%20submission%20Mar%202016%20revised%20after%20proofing%20check.pdf}}</ref> 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 [[joist]]s than C24 can offer. TR26 is also a common trussed rafter strength class in long standing use in the UK.<ref>{{cite web|url=http://blogs.napier.ac.uk/cwst/what-is-tr26/|title=What is TR26? |publisher= Centre for Wood Science & Technology|date=1 December 2015}}</ref><ref>{{cite journal |last1=Ridley-Ellis |first1=Dan |last2=Gil-Moreno |first2=David |last3=Harte |first3=Annette M. |title=Strength grading of timber in the UK and Ireland in 2021 |journal=International Wood Products Journal |date=19 March 2022 |volume=13 |issue=2 |pages=127–136 |doi=10.1080/20426445.2022.2050549 |s2cid=247578984 |issn=2042-6445|doi-access=free |hdl=10379/17124 |hdl-access=free }}</ref>
* C40, usually seen in [[glulam]]

Grading rules for African and South American sawn lumber have been developed by ATIBT<ref>{{Cite web |url=http://www.atibt.com/ |title=ATIBT |access-date=23 July 2014 |archive-date=16 May 2014 |archive-url=https://web.archive.org/web/20140516233446/http://atibt.com/ |url-status=dead }}</ref> 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.<ref name="fordaq">{{cite web|title=African and South American sawn timber|url=http://www.fordaq.com/fordaq/html/quality_africa_sata_En.htm|website=www.fordaq.com|publisher=Fordaq S.A., The Timber Network|access-date=7 May 2017}}</ref>

===North American hardwoods===
In North America, market practices for dimensional lumber made from hardwoods{{efn
  |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 tabletop [[jointer|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 [[cabinetry|cabinets]] or furniture with the boards.
  }} varies significantly from the regularized ''standardized '[[dimension lumber]]' sizes'' used for sales and specification of softwoods – hardwood boards are often sold totally rough cut,{{ efn
 | In quarter sawn thicknesses, meaning the thickness and width dimensions as they come out of the sawmill's table. Because lengths vary most with temperature, hardwood boards in the US often have a bit of extra length.
 }} 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 lumber) 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 store]]s and using only a relatively small set of specified lengths;{{efn
  |Small set of specified lengths: Fixed-length hardwood boards in the United States are most common in {{convert|4|–|6|ft|abbr=on}} lengths, with a good representation of {{convert|8|ft|abbr=on}} lengths in a variety of widths, and a few widths with occasional dimensional sizes to {{convert|12|ft|abbr=on}} lengths. Often the longer sizes need be special ordered.
  }} in all cases hardwoods are sold to the consumer by the [[board-foot]] ({{convert|144|cuin|disp=or}}), whereas that [[measurement system|measure]] is not used for softwoods at the retailer (to the cognizance of the buyer).{{efn
  |name=On Australia|1= Fixed board lengths do 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.}}

{| class="wikitable" style="text-align:center"
|+ North American hardwood dimensional lumber sizes
|-
! Nominal (rough-sawn size)
! S1S (surfaced on one side)
! S2S (surfaced on two sides)
|-
| {{frac|1|2}} in
| {{convert|3/8|in|abbr=on}}
| {{convert|5/16|in|abbr=on}}
|-
| {{frac|5|8}} in
| {{convert|1/2|in|abbr=on}}
| {{convert|7/16|in|abbr=on}}
|-
| {{frac|3|4}} in
| {{convert|5/8|in|abbr=on}}
| {{convert|9/16|in|abbr=on}}
|-
| 1 in or {{frac|4|4}} in
| {{convert|7/8|in|abbr=on}}
| {{convert|13/16|in|abbr=on}}
|-
| {{frac|1|1|4}} in or {{frac|5|4}} in
| {{convert|1+1/8|in|abbr=on}}
| {{convert|1+1/16|in|abbr=on}}
|-
| {{frac|1|1|2}} in or {{frac|6|4}} in
| {{convert|1+3/8|in|abbr=on}}
| {{convert|1+5/16|in|abbr=on}}
|-
| 2 in or {{frac|8|4}} in
| {{convert|1+13/16|in|abbr=on}}
| {{convert|1+3/4|in|abbr=on}}
|-
| 3 in or {{frac|12|4}} in
| {{convert|2+13/16|in|abbr=on}}
| {{convert|2+3/4|in|abbr=on}}
|-
| 4 in or {{frac|16|4}} in
| {{convert|3+13/16|in|abbr=on}}
| {{convert|3+3/4|in|abbr=on}}
|+
|}

Also in North America, hardwood lumber is commonly sold in a "quarter" system, when referring to thickness; 4/4 (four quarter) refers to a {{convert|1|in|mm|adj=mid|-thick}} board, 8/4 (eight quarter) is a {{convert|2|in|mm|adj=mid|-thick}} 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 {{convert|1/8|in|abbr=on|disp=or}} off each side in a motorized [[thickness planer|planing]] step of production). The "quarter" system of reference is a traditional North American lumber industry nomenclature used specifically to indicate the thickness of rough sawn hardwood lumber.

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 include {{frac|3|4}}-inch, 19&nbsp;mm, or 1x. In recent years{{when|date=February 2020}} architects, designers, and builders{{who|date=September 2023}} 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 lumber and decreases the value of the wood for furniture.

===Engineered lumber===
{{main|Engineered lumber}}

[[Engineered lumber]] is lumber created by a manufacturer and designed for a certain structural purpose. The main categories of engineered lumber are:<ref>{{cite web|title=Austin Energy page describing engineered structural lumber|url=http://www.austinenergy.com/Energy%20Efficiency/Programs/Green%20Building/Sourcebook/engineeredStructuralProducts.htm|access-date=2006-09-10|url-status=dead|archive-url=https://web.archive.org/web/20060822023120/http://www.austinenergy.com/Energy%20Efficiency/Programs/Green%20Building/Sourcebook/engineeredStructuralProducts.htm|archive-date=2006-08-22}}</ref>
* [[Laminated veneer lumber|Laminated veneer lumber (LVL)]] – LVL comes in {{convert|1+3/4|in|adj=on}} thicknesses with depths such as {{convert|9+1/2|,|11+7/8|,|14|,|16|,|18|and|24|in}}, 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) (or, latterly, steel mesh forms which allow passage of services without cutting). 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.
* [[Finger joint|Finger-jointed lumber]] – solid dimensional lumber lengths typically are limited to lengths of {{convert|22|to(-)|24|ft}}, but can be made longer by the technique of "finger-jointing" by using small solid pieces, usually {{convert|18|to(-)|24|in}} long, and joining them together using finger joints and glue to produce lengths that can be up to {{convert|36|ft}} 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.
* [[Glued laminated timber|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.
* [[Truss|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|Woodworking}}
* Square and rectangular forms: [[Plank (wood)|plank]], [[wikt:slat|slat]], [[batten]], [[wikt:board|board]], [[lath]], ''strapping'' (typically {{cvt|3/4|x|1+1/2|in|disp=sqbr}}), ''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 (structural)|post]], [[beam (structure)|beam]], ([[girt]]), [[Wall stud|stud]], [[rafter]], [[joist]], [[sill plate]], [[wall plate]].
*Rod forms: [[Utility pole|pole]], ([[dowel]]), stick (staff, baton)

===Timber piles===
In the United States, [[piling]]s are mainly cut from [[southern yellow pine]]s and [[Douglas-fir]]. [[Wood preservation|Treated]] pilings are available in [[chromated copper arsenate]] retentions of {{convert|0.60|,|0.80|and|2.50|lb/cuft|kg/m3}} if treatment is required.

===Historical Chinese construction===
Under the prescription of the ''[[Yingzao Fashi|Method of Construction]]'' (營造法式) issued by the [[Song dynasty]] government in the early twelfth century, timbers were standardized to eight cross-sectional dimensions.<ref>{{cite book|last1=李|first1=誡|title=營造法式|date=1103|publisher=Song Government|location=China|url=https://zh.wikisource.org/wiki/%E7%87%9F%E9%80%A0%E6%B3%95%E5%BC%8F/%E7%AC%AC%E5%9B%9B%E5%8D%B7|access-date=8 May 2016}}</ref> 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 (31.2&nbsp;mm).
{| class="wikitable"
|-
! Class !! height !! width !! uses
|-
| 1st || 9 || 6 || great halls 11 or 9 bays wide
|-
| 2nd || 8.25  || 5.5 || great halls 7 or 5 bays wide
|-
| 3rd || 7.5 || 5 || great halls 5 or 3 bays wide or halls 7 or 5 bays wide
|-
| 4th || 7.2 || 4.8 || great halls 3 bays wide or halls 5 bays wide
|-
| 5th || 6.6 || 4.4|| great halls 3 small bays wide or halls 3 large bays wide
|-
| 6th || 6 || 4 || pagodas and small halls
|-
| 7th || 5.25 || 3.2 || pagodas and small great halls
|-
| 8th || 4.5 || 3 || 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 applications show a gradual diminution from the Sui dynasty (580–618) to the modern era; a 1st class timber during the Sui was reconstructed as 15×10 (Sui dynasty inches, or 29.4&nbsp;mm).<ref>{{cite journal|last1=王|first1=貴祥|title=关于隋唐洛阳宫乾阳殿与乾元殿的平面_结构与形式之探讨|journal=中國建築史論匯刊|volume=3|page=116}}</ref>

==Defects in lumber==

{{Expand German|Holzfehler|date=May 2016}}

Defects occurring in lumber are grouped into the following four divisions:

===Conversion===
During the process of converting timber to commercial forms of lumber 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 dent 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 wood (both timber and lumber) when these conditions are all present:
* The wood moisture content is above 25% on a dry-weight basis
* The environment is sufficiently warm
* Oxygen (O<sub>2</sub>) 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 lumber/timber defects:
* [[Blue stain fungus|Blue stain]]
* [[Wood-decay fungus|Brown rot]]
* [[Dry rot]]
* [[Heart rot]]
* Sap stain
* [[Wet rot]]
* [[White rot]]

Following are the insects and [[molluscs]] which are usually responsible for the decay of timber/lumber:
* [[Woodboring beetle]]s
* Marine borers ([[Barnea similis]])
* Teredos ([[Teredo navalis]])
* [[Termites]]
* [[Carpenter ants]]
* [[Carpenter bee]]s

===Natural forces===
{{Main|Wood warping}}

There are two main natural forces responsible for causing defects in timber and lumber: 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]].<ref name=DA>U. S. Department of Agriculture. "Shake", ''The Encyclopedia of Wood''. New York: [[Skyhorse Pub.]], 2007. Print.</ref> 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 locations.<ref name=DA/>

Next to defects, uneven expansion or contraction caused by changes in moisture content will cause sawed timber to warp, making it less suitable for many purposes.

===Seasoning===
The [[Wood drying|seasoning]] of lumber is typically either kiln- or air-dried. Defects due to seasoning are the main cause of splits, bowing and honeycombing. Seasoning is the process of drying timber to remove the bound moisture contained in the walls of the wood cells to produce seasoned timber.<ref>{{Cite news|url=https://www.woodworkingnetwork.com/best-practices-guide/solid-wood-machining/understanding-working-wood-defects|title=Understanding & working with wood defects|last=karenkoenig|date=2016-04-04|work=Woodworking Network|access-date=2018-03-12|language=en}}</ref>

==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 practices

===Moisture control===
Wood is a [[Hygroscopy|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 [[Timber framing|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 [[preservative]]s. [[Cladding (construction)|Cladding]], [[Shake (shingle)|shingles]], [[sill plate]]s and exposed timbers or [[Glued laminated timber|glulam beams]] are examples of potential applications for treated wood.

===Preservatives===
{{Main|Wood preservation}}
[[File:Treated timber.jpg|thumb|upright|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 preservative-treated wood.<ref>{{cite web|url=http://www.woodworks.org/files/PDF/publications/wood-design-durability-service-life-fact-sheet.pdf|title=WoodWorks Durability and Service Life|access-date=2011-06-01|archive-url=https://web.archive.org/web/20120405185524/http://www.woodworks.org/files/PDF/publications/wood-design-durability-service-life-fact-sheet.pdf|archive-date=2012-04-05|url-status=dead}}</ref>

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.<ref>[https://books.google.com/books?id=0SkDAAAAMBAJ&pg=PA59 "Wood That Fights."] ''Popular Sciences'', March 1944, p. 59.</ref> 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 salt.<ref>[https://books.google.com/books?id=lNsDAAAAMBAJ&pg=PA560 "Lumber is Made Fireproof by Salt Treatment" ''Popular Mechanics'', April 1936] bottom-left p. 560</ref> 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.<ref name="About Treated Wood - CWC">{{cite web|title=About Treated Wood|url=http://cwc.ca/design-with-wood/durability/pressure-treated-wood/about-treated-wood/|archive-url=https://web.archive.org/web/20150203121514/http://cwc.ca/design-with-wood/durability/pressure-treated-wood/about-treated-wood/|url-status=dead|archive-date=3 February 2015|website=CWC|access-date=7 May 2017}}</ref>

There are two basic methods of treating: with and without pressure. Non-pressure methods are the application of preservatives 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 Canada are registered and regularly re-examined for safety by the U.S. Environmental Protection Agency and Health Canada's Pest Management and Regulatory Agency, respectively.<ref name="About Treated Wood - CWC"/>

==Timber framing==
{{Main|Timber framing}}
''Timber framing'' is a style of construction that uses heavier framing elements (larger posts and beams) than modern [[Framing (construction)|stick framing]], which uses smaller standard dimensional lumber. The timbers are cut from log [[Bole (botany)|boles]] and squared with a saw, broadaxe or adze, and then joined together with joinery without nails. Modern timber framing has been growing in popularity in the United States since the 1970s.<ref>Roy, Robert L. Timber framing for the rest of us. Gabriola Island, BC: New Society Publishers, 2004. 6. Print. {{ISBN|0865715084}}</ref>

==Environmental effects of lumber==
Green building minimizes the impact or "environmental footprint" of a building. Wood is a major building material that is renewable and replenishable in a continuous cycle.<ref name="About Treated Wood - CWC"/> Studies show manufacturing wood uses less energy and results in less air and water pollution than steel and concrete.<ref>[http://www.corrim.org/pubs/articles/2011/FSG_Review_Carbon_Synthesis.pdf 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.] {{webarchive|url=https://web.archive.org/web/20111110121510/http://www.corrim.org/pubs/articles/2011/FSG_Review_Carbon_Synthesis.pdf |date=2011-11-10 }}</ref> However, demand for lumber is blamed for [[deforestation]].<ref>[[Peter Dauvergne]] and Jane Lister, ''[https://www.polity.co.uk/resources/peter-timber.asp Timber] {{webarchive|url=http://arquivo.pt/wayback/20160522205904/https%3A//www.polity.co.uk/resources/peter%2Dtimber.asp |date=2016-05-22 }}'' (Polity Press, 2011).</ref>

===Residual wood===
The conversion from coal to [[biomass]] power is a growing trend in the United States.<ref>{{Cite web |url=http://apps1.eere.energy.gov/news/enn.cfm#id_11950 |title=EERE News: EERE Network News<!-- Bot generated title --> |access-date=29 March 2011 |archive-date=29 May 2011 |archive-url=https://web.archive.org/web/20110529013518/http://apps1.eere.energy.gov/news/enn.cfm#id_11950 |url-status=dead }}</ref>

The United Kingdom, Uzbekistan, Kazakhstan, Australia, Fiji, Madagascar, Mongolia, Russia, Denmark, Switzerland, and Eswatini 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]], saw milling and paper-making processes. In particular, they view it as a way to lower greenhouse gas emissions by reducing the 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.<ref>[http://feedstockreview.ornl.gov/pdf/billion_ton_vision.pdf U.S. Department of Agriculture, U.S. Department of Energy Biomass as a Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply, 2005 Executive Summary] {{webarchive|url=https://web.archive.org/web/20080825173945/http://feedstockreview.ornl.gov/pdf/billion_ton_vision.pdf |date=2008-08-25 }}</ref>

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.

== Environmental impacts ==
Lumber is a sustainable and environmentally friendly construction material that could replace modern building materials (e.g. concrete and steel) given its structural performance, capacity to fixate CO<sub>2</sub> and low energy demand during the manufacturing process.<ref name="Roberts 2020 r215">{{cite web | last=Roberts | first=David | title=The hottest new thing in sustainable building is, uh, wood | website=Vox | date=15 January 2020 | url=https://www.vox.com/energy-and-environment/2020/1/15/21058051/climate-change-building-materials-mass-timber-cross-laminated-clt | access-date=5 April 2024}}</ref>

Substituting lumber for concrete or steel avoids the carbon emissions of those materials. Cement and concrete manufacture is responsible for around 8% of global GHG emissions while the iron and steel industry is responsible for another 5% (half a ton of CO<sub>2</sub> is emitted to manufacture a ton of concrete; two tons of CO<sub>2</sub>  are emitted in the manufacture of a ton of steel).<ref>{{cite web|title=Energy Technology Perspectives 2016 – Analysis|url=https://www.iea.org/reports/energy-technology-perspectives-2016|access-date=2021-10-08|website=IEA|date=June 2016 |language=en-GB}}</ref>

'''Advantages of lumber:'''

* '''Fire performance:''' In the case of fire, the outer layer of mass timber will tend to char in a predictable way that effectively self-extinguishes and shields the interior, allowing it to retain structural integrity for several hours, even in an intense fire.
* '''Reduction of carbon emissions:''' Building materials and construction make up 11% of global greenhouse gas emissions. Though the exact amount will depend on tree species, forestry practices, transportation costs, and several other factors, that one cubic meter of lumber sequesters roughly one tonne of CO<sub>2</sub>.<ref>{{Cite journal|last1=Puettmann|first1=Maureen|last2=Sinha|first2=Arijit|last3=Ganguly|first3=Indroneil|date=2019-09-01|title=Life Cycle Energy and Environmental Impacts of Cross Laminated Timber Made with Coastal Douglas-fir|journal=Journal of Green Building|volume=14|issue=4|pages=17–33|doi=10.3992/1943-4618.14.4.17|s2cid=214201061|issn=1552-6100|doi-access=free}}</ref> It is estimated that wood can reduce the amount of CO<sub>2</sub> released into the atmosphere by half.<ref>{{Cite book |last=Hurmekoski |first=Elias |url=https://efi.int/sites/default/files/files/publication-bank/2018/efi_hurmekoski_wood_construction_2017_oct.pdf |title=How can wood construction reduce environmental degradation? |date=April 2017 |publisher=European Forest Institute |page=3}}</ref><ref>{{Cite web |title=Could wooden buildings be a solution to climate change? |url=https://www.bbc.com/future/article/20190717-climate-change-wooden-architecture-concrete-global-warming |access-date=2024-07-10 |website=www.bbc.com |date=25 July 2019 |language=en-GB}}</ref> In addition, wood has a significant CO<sub>2</sub> storage capacity, which limits its release. However, when wood is destroyed (naturally or by combustion), all of the previously stored CO<sub>2</sub> is released into the atmosphere.<ref>{{Cite web |title=Wood burning and our climate |url=https://www.dsawsp.org/environment/climate |access-date=2024-07-10 |website=www.dsawsp.org |language=en}}</ref>
* '''Natural insulation:''' lumber is a natural insulator which makes it particularly good for windows and doors.
* '''Less construction time, labor costs, and waste:''' it is easy to manufacture prefabricated lumber, from which pieces can be assembled simultaneously (with relatively little labor). This reduces material waste, avoids massive on-site inventory, and minimizes on-site disruption. According to the softwood lumber industry, "Mass timber buildings are roughly 25% faster to construct than concrete buildings and require 90% less construction traffic".<ref>{{cite web|date=2018-04-25|title=4 Things to Know About Mass Timber|url=https://www.thinkwood.com/blog/4-things-to-know-about-mass-timber|access-date=2021-10-08|website=Think Wood|language=en-us}}</ref>

== End-of-life ==
An EPA study showed the typical end-of-life scenario for wood waste from municipal solid waste (MSW), wood packaging, and other miscellaneous wood products in the US. Based on the 2018 data, about 67% of wood waste was landfilled, 16% incinerated with energy recovery, and 17% recycled.<ref>[https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/wood-material-specific-data EPA’s study on Wood Waste]</ref>

A 2020 study conducted by [[Edinburgh Napier University]] demonstrated the proportional waste stream of recovered lumber in the UK. The study showed that timber from municipal solid waste and [[packaging waste]] made up 13 and 26% of waste collected. Construction and demolition waste made up the biggest bulk of waste collectively at 52%, with the remaining 10% coming from industry.<ref name=":1">{{Cite web |last=cramer |first=marlene |date=2020-11-02 |title=Insights in Timber Recycling and Demolition |url=https://blogs.napier.ac.uk/cwst/timber-recycling-and-demolition/ |access-date=2024-02-10 |website=Centre for Wood Science & Technology |language=en-US}}</ref>

== In the circular economy ==
The lumber industry creates large amounts of waste, especially in its manufacturing process. From log debarking to finished products, there are several stages of processing that generate a considerable volume of waste, which includes solid wood waste, harmful gases, and residual water.<ref name=":0">{{Cite journal|last1=de Carvalho Araújo|first1=Cristiane Karyn|last2=Salvador|first2=Rodrigo|last3=Moro Piekarski|first3=Cassiano|last4=Sokulski|first4=Carla Cristiane|last5=de Francisco|first5=Antonio Carlos|last6=de Carvalho Araújo Camargo|first6=Sâmique Kyene|date=January 2019|title=Circular Economy Practices on Wood Panels: A Bibliographic Analysis|journal=Sustainability|language=en|volume=11|issue=4|page=1057|doi=10.3390/su11041057|bibcode=2019Sust...11.1057D |doi-access=free|hdl=11449/187368|hdl-access=free}}</ref>

One of the studies conducted in Hong Kong<ref name=":0" /> was done using [[life-cycle assessment]] (LCA). The study aimed to assess and compare the environmental impacts of wood waste management from building construction activities using different alternative management scenarios in Hong Kong. Despite various advantages of lumber and its waste, the contribution to the study of the circular economy of lumber is still very small. Some areas where improvements can be made to improve the circularity of lumber is as follows:

# First, regulations to support recycled lumber use. For example, establishing grading standards and enforcing penalties for improper disposal, especially in sectors that produce big quantities of wood waste, such as the construction and demolition sector. 
# Second, creating a stronger supply force. This can be achieved by improving demolition protocol and technology and enhancing the secondary raw materials market through circular business models. 
# Third, increase demand by introducing incentives to the construction sector and new homeowners to use recycled lumber. This can be in the form of reduced taxes for the construction of the new build.

== Secondary raw material ==
The term [[Raw material|''secondary raw material'']] denotes waste material that has been recycled and injected back into use as productive material. Lumber has a high potential to be used as a secondary raw material at various stages, as listed below:

;Recovery of branches and leaves for use as fertilisers
:Timber undergo multiple processing stages before lumber of desired shapes, size, and standards are achieved for commercial use. The process generates a lot of waste which in most cases is disregarded. But being an organic waste, the positive aspect of such waste is that it can be used as a fertiliser or to protect the soil in severe weather conditions.
;Recovery of [[woodchips]] for thermal energy generation
:Waste generated during the manufacturing of lumber products can be used to produce thermal energy. Lumber products after their end-of-life can be [[downcycle]]d into chips and be used as biomass to produce thermal energy.<ref name=":1" /> It is beneficial for industries that need thermal energy.

Circular economy practices offer effective solutions concerning waste. It targets its unnecessary generation through waste reduction, reuse, and recycling. There is no clear explicit evidence of circular economy in the wood panel industry. However, based on the circular economy concept and its characteristics, there are opportunities present in the wood panel industry from the raw material extraction phase to its end-of-life. Therefore, there lies a gap yet to be explored.<ref name=":0" />

== See also ==
{{Portal|Trees}}
{{Div col}} 
* [[Cubic ton]]
* [[Deck (building)]]
* [[Engineered wood]]
* [[Forestry]]
* [[Hardwood timber production]]
* [[List of woods]]
* [[Log house]]
* [[Lumber room]]
* [[Lumberjack]]
* [[Natural building]]
* [[Reclaimed lumber]]
* [[Recycling timber]]
* [[Table of Wood and Bamboo Mechanical and Agricultural Properties]]
* [[Timber treatment]]
* [[Wood industry]]
* [[Woodworking]]
* [[Yakisugi]]
{{Div col end}}

== Explanatory notes ==
{{notelist}}

==References==
{{Reflist}}

==Further reading==
* Davis, Richard C. ''Encyclopedia of American forest and conservation history'' (1983) [https://archive.org/details/encyclopediaofam01davi vol 1 online] see also [https://archive.org/details/encyclopediaofam02davil 2 online], 871pp. See [https://www.journals.uchicago.edu/doi/abs/10.2307/4004699?journalCode=jforehist online review of this book]
* {{cite book
 |last1=Sathre
 |first1=R
 |title=A Synthesis of Research on Wood Products and Greenhouse Gas Impacts
 |publisher=FPInnovations
 |isbn=978-0-86488-546-3
 |url=http://www.forintek.ca/public/pdf/Public_Information/technical_rpt/TR19%20Complete%20Pub-web.pdf
 |edition=2nd
 |last2=O'Conner
 |first2=J
 |year=2010
 |url-status=dead
 |archive-url=https://web.archive.org/web/20120321215904/http://www.forintek.ca/public/pdf/Public_Information/technical_rpt/TR19%20Complete%20Pub-web.pdf
 |archive-date=2012-03-21
}}

==External links==
{{Wiktionary|lumber|timber}}
{{commons category|Timber}}
* [http://www.nhla.com/ National Hardwood Lumber Association] (Rules for Grading Hardwood Lumber – Inspector Training School)
* [http://timber.net.au/ Timber Development Association of NSW] – Australia
* [http://www.tda.org.uk/ TDA: Timber Decking Association] – UK
* [http://www.trada.co.uk/ TRADA: Timber Research And Development Association] {{Webarchive|url=https://web.archive.org/web/20100306013214/http://www.trada.co.uk/ |date=6 March 2010 }}
* [http://www.fpl.fs.fed.us/ The Forest Products Laboratory. U.S. main wood products research lab. Madison, WI (E)]
* [http://www.wcte2010.org/ WCTE, World Conference on Timber Engineering] {{Webarchive|url=https://web.archive.org/web/20100127014735/http://www.wcte2010.org/ |date=27 January 2010 }}　June 20–24, 2010, Riva del Garda, Trentino, Italy
* [https://web.archive.org/web/20140912183307/http://nfdp.ccfm.org/products/national_e.php Forest Products data in Canada since 1990]

{{Wood products}}
{{Woodworking}}
{{Authority control}}

[[Category:Forestry]]
[[Category:Timber industry]]
[[Category:Wood products]]
[[Category:Woodworking]]
[[Category:Wood-related terminology]]