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==Dimensional lumber== [[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 × 2''' | {{frac|3|4}} × {{frac|1|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 19 × 38 | '''2 × 2''' | {{frac|1|1|2}} × {{frac|1|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 38 × 38 | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 | |- | '''1 × 3''' | {{frac|3|4}} × {{frac|2|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 19 × 64 | '''2 × 3''' | {{frac|1|1|2}} × {{frac|2|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 38 × 64 | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 | |- | '''1 × 4''' | {{frac|3|4}} × {{frac|3|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 19 × 89 | '''2 × 4''' | {{frac|1|1|2}} × {{frac|3|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 38 × 89 | '''4 × 4''' | {{frac|3|1|2}} × {{frac|3|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 89 × 89 | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 | |- | '''1 × 5''' | {{frac|3|4}} × {{frac|4|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 19 × 114 | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 | |- | '''1 × 6''' | {{frac|3|4}} × {{frac|5|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 19 × 140 | '''2 × 6''' | {{frac|1|1|2}} × {{frac|5|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 38 × 140 | '''4 × 6''' | {{frac|3|1|2}} × {{frac|5|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 89 × 140 | '''6 × 6''' | {{frac|5|1|2}} × {{frac|5|1|2}} | style="border-right-style:solid; border-right-width:3px;" | 140 × 140 | colspan=3 | |- | '''1 × 8''' | {{frac|3|4}} × {{frac|7|1|4}} | style="border-right-style:solid; border-right-width:3px;" | 19 × 184 | '''2 × 8''' | {{frac|1|1|2}} × {{frac|7|1|4}} | style="border-right-style:solid; border-right-width:3px;" | 38 × 184 | '''4 × 8''' | {{frac|3|1|2}} × {{frac|7|1|4}} | style="border-right-style:solid; border-right-width:3px;" | 89 × 184 | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | '''8 × 8''' | {{frac|7|1|2}} × {{frac|7|1|2}} | 191 × 191 |- | '''1 × 10''' | {{frac|3|4}} × {{frac|9|1|4}} | style="border-right-style:solid; border-right-width:3px;" | 19 × 235 | '''2 × 10''' | {{frac|1|1|2}} × {{frac|9|1|4}} | style="border-right-style:solid; border-right-width:3px;" | 38 × 235 | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 | |- | '''1 × 12''' | {{frac|3|4}} × {{frac|11|1|4}} | style="border-right-style:solid; border-right-width:3px;" | 19 × 286 | '''2 × 12''' | {{frac|1|1|2}} × {{frac|11|1|4}} | style="border-right-style:solid; border-right-width:3px;" | 38 × 286 | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 style="border-right-style:solid; border-right-width:3px;" | | colspan=3 | |} 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, 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 {{frac|3|4}} inch; while the dressed size of 2 inch (nominal) lumber was ''reduced'' from {{frac|1|5|8}} inch to the current {{frac|1|1|2}} 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=== [[File:The longest board in the world (2002).jpg|thumb|The longest plank in the world (2002) is in Poland (near 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 }}</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 – {{frac|3|4}}-inch, 19 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 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 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>
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