Editing Lumber (section)

===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.