Editing Lumber (section)

===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 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 | &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
| colspan=3 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 | &nbsp;

|-
| '''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
| colspan=3 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 | &nbsp;

|-
| '''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;
| colspan=3 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 | &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
| colspan=3 | &nbsp;

|-
| '''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 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 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 | &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
| colspan=3 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 style="border-right-style:solid; border-right-width:3px;" | &nbsp;
| colspan=3 | &nbsp;
|}

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}}&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.