Oriented strand board
Oriented strand board(OSB) is a type ofengineered woodsimilar toparticle board,formed by addingadhesivesand then compressing layers ofwoodstrands (flakes) in specific orientations. It was invented by Armin Elmendorf in California in 1963.[1]OSB may have a rough andvariegatedsurface with the individual strips of around 2.5 cm × 15 cm (1.0 by 5.9 inches), lying unevenly across each other, and is produced in a variety of types and thicknesses.
Oriented strand board is sometimes confused withchipboard,a synonym forparticle board,whose "chips" are of a size that a lay person would likely describe as "particles".
Uses
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OSB is a material with favorable mechanical properties that make it particularly suitable for load-bearing applications inconstruction.[2]It is now more popular thanplywood,commanding 66% of the North American structural panel market.[3]The most common uses are assheathingin walls, flooring, and roof decking. For exterior wall applications, panels are available with aradiant-barrierlayer laminated to one side; this eases installation and increases energy performance of thebuilding envelope.OSB is also used infurnitureproduction.
Manufacturing
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Oriented strand board is manufactured in wide mats from cross-oriented layers of thin, rectangular wooden stripscompressedand bonded together withwaxand syntheticresinadhesives.
The adhesive resins types used include:urea-formaldehyde(OSB type 1, nonstructural, nonwaterproof);isocyanate-based glue (orPMDIpoly-methylene diphenyl diisocyanatebased) in inner regions withmelamine-urea-formaldehydeorphenol formaldehyde resinglues at surface (OSB type 2, structural, water resistant on face);phenol formaldehyde resinthroughout (OSB types 3 and 4, structural, for use in damp and outside environments).[4]
The layers are created by shredding the wood into strips, which are sifted and then oriented on a belt orwire-mesh caul(a heated, ventilated support) and coated with the resin.[5]The layers thus built up are transferred to a forming line and cross-oriented so that strips on the external layers are aligned to the panel's strength axis, while the internal layers are perpendicular.[6]The number of layers placed is determined partly by the thickness of the panel, but is limited by the equipment installed at the manufacturing site. Individual layers can also vary in thickness to give different finished panel thicknesses; typically, a 15 cm (5.9 in) layer will produce a 15 mm (0.59 in) panel thickness[citation needed].The mat is placed in a thermal press to compress the flakes and bond them by heat activation and curing of the resin that has been coated on the flakes. Individual panels are then cut from the mats into finished sizes. Most of the world's OSB is made in theUnited StatesandCanadain large production facilities.
Related products
[edit]Materials other than wood have been used to produce products similar to OSB.Oriented structural straw boardis an engineered board made by splitting straw and formed by adding P-MDI adhesives and then hot compressing layers of straw in specific orientations.[7]Strand board can also be made frombagasse.
Production
[edit]In 2005, Canadian production was 10,500,000 m2(113,000,000 sq ft) (3⁄8in or 9.53 mm basis) of which 8,780,000 m2(94,500,000 sq ft) (3⁄8inch) were exported, almost entirely to the United States.[8]In 2014,Romaniabecame the largest OSB exporting country in Europe, with 28% of the exports going toRussiaand 16% toUkraine.[9]
Properties
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Adjustments to the manufacturing process can affect thickness, panel size,strength,andrigidity.OSB panels have no internal gaps or voids, and can be water-resistant, although they do require additionalmembranesto achieve impermeability to water and are not recommended for exterior use. The finished product has properties similar toplywood,but is uniform and cheaper.[10]When tested to failure, OSB has a greater load-bearing capacity than milled wood panels.[11]It has replaced plywood in many environments, especially the North American structural panel market.
While OSB does not have a continuousgrainlike a natural wood, it does have greater strength on its long axis because more of the component grains are oriented in this direction. This can be seen by observing the alignment of the surface wood chips.
All wood-based structural use panels can be cut and installed with the same types of equipment as for solid wood.
Health and safety
[edit]The resins used to create OSB[12]have raised questions regarding the potential for OSB to emitvolatile organic compoundssuch asformaldehyde.Urea-formaldehydeis more toxic and should be avoided in home use.Phenol-formaldehydeproducts are considered to be relatively hazard free. Some newer types of OSB, so-called "new-generation" OSB panels, useisocyanate resinsthat do not contain formaldehyde and are considered nonvolatile when cured.[13]Industry trade groups assert that formaldehyde emissions from North American OSB are "negligible or nonexistent".[14]
Some manufacturers treat the wood chips with variousboratecompounds that are toxic totermites,wood-boringbeetles,molds,andfungi,but notmammalsin applied doses.
Types
[edit]Five grades of OSB are defined in EN 300 in terms of their mechanical performance and relative resistance to moisture:[2]
- OSB/0 – No added formaldehyde
- OSB/1 – General-purpose boards and boards for interior fitments (including furniture) for use in dry conditions
- OSB/2 – Load-bearing boards for use in dry conditions
- OSB/3 – Load-bearing boards for use in humid conditions
- OSB/4 – Heavy-duty load-bearing boards for use in humid conditions
References
[edit]- ^"Dokument US000003164511A"(PDF).DEPATISnet.Deutsches Patent- und Markenamt.Retrieved2 May2016.
- ^ab"Technical Information".Osb-info.org. Archived fromthe originalon 2016-05-09.Retrieved2016-05-02.
- ^Marotte, Bertrand (19 July 2016)."Toronto's Norbord riding the rising wave of OSB sales".The Globe and Mail.Retrieved20 September2017.
- ^Oldhand, Tony (25 Apr 2017),"Types of Glue Used in OSB",sciencing.com
- ^Koch, Peter (1985).Utilization of hardwoods growing on southern pine sites.Washington, DC: U.S. Dept. of Agriculture, Forest Service. p. 2423.OCLC13459178.
- ^Hedges, Keith E. (2017). "Oriented Strand Board".Architectural Graphic Standards(12 ed.). Hoboken, NJ:Wiley.ISBN9781119312512.
- ^Han, Guangping, Cheng, Wanli, Manning, Mark, and Eloy, Pierre (2012)."Performance of zinc Borate Treated Oriented Structural Straw Board against Mold Fungi, Decay Fungi, and Termites - A preliminary trial"(PDF).BioResources.7(3): 2986–2995.doi:10.15376/biores.7.3.2986-2995.
{{cite journal}}:CS1 maint: multiple names: authors list (link) - ^"Review of the Canadian structural panel market".Fordaq.com. 24 August 2006.Retrieved2016-05-02.
- ^"Romania has become the largest OSB exporting country in the EU".Fordaq.Fordaq S.A. 7 April 2014.
- ^"UMass Amherst: Building and Construction Technology » Choosing Between Oriented Strandboard and Plywood".Umass.edu. 2015-09-04.Retrieved2016-05-02.
- ^Chaya Kurtz (2010-05-12)."Experts Talk About Engineered Wood - Articles".Networx.com.Retrieved2016-05-02.
- ^Mantanis,George I.; Athanassiadou, Eleftheria Th.; Barbu, Marius C.; Wijnendaele, Kris (2018-03-15). "Adhesive systems used in the European particleboard, MDF and OSB industries".Wood Material Science & Engineering.13(2): 104–116.doi:10.1080/17480272.2017.1396622.ISSN1748-0272.
- ^MacLeod, Ian."I'm concerned about toxic offgassing from OSB subflooring and roofing".Green home guide.Archived fromthe originalon 2016-06-05.Retrieved2015-11-14.
- ^"Oriented Strand Board Educational Bulletin, Frequently Asked Questions"(PDF).OSBGuide.TECOTested.com. Archived fromthe original(PDF)on 4 March 2016.Retrieved2 May2016.
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| Engineered wood | |
| Fuelwood | |
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