# Oriented strand board

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Engineered wood particle board

OSB is easily identifiable by its characteristic wood strands.

**Oriented strand board** (**OSB**) is a type of [engineered wood](/source/Engineered_wood), formed by adding [adhesives](/source/Adhesive) to layers of [wood](/source/Wood) strands (flakes) laid in specific orientations and compressing them. It was invented by Armin Elmendorf in California in 1963.[1] OSB may have a rough and [variegated](/source/Variegation) surface 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 with *chipboard*, a synonym for [particle board](/source/Particle_board), whose "chips" are of a size that a lay person would likely describe as "particles".

## Uses

OSB is frequently used in light [steel frame](/source/Steel_frame) house construction.

OSB's mechanical properties make it suitable for load-bearing applications in [construction](/source/Construction).[2] In North America, it is more popular than [plywood](/source/Plywood), commanding 66% of the structural panel market in 2016.[3] The most common uses are as [sheathing](/source/Siding_(construction)) in walls, flooring, and roof decking. For exterior walls, panels are available with a [radiant-barrier](/source/Radiant_barrier) layer laminated to one side; this eases installation and increases energy performance of the [building envelope](/source/Building_envelope). OSB is also used in [furniture](/source/Furniture) production.

## Manufacturing

OSB in production before pressing in a thermal press

Oriented strand board is manufactured in wide mats from cross-oriented layers of thin, rectangular wooden strips [compressed](/source/Compression_(physical)) and bonded together with [wax](/source/Wax) and synthetic [resin](/source/Resin) [adhesives](/source/Adhesive).

The adhesive resins types used include: [urea-formaldehyde](/source/Urea-formaldehyde) (OSB type 1, nonstructural, nonwaterproof); [isocyanate](/source/Isocyanate)-based glue (or [PMDI](/source/PMDI) poly-methylene diphenyl diisocyanate–based) in inner regions with [melamine-urea-formaldehyde](/source/Melamine-urea-formaldehyde) or [phenol formaldehyde resin](/source/Phenol_formaldehyde_resin) glues at surface (OSB type 2, structural, water resistant on face); phenol formaldehyde resin throughout (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 or [wire-mesh caul](https://en.wikipedia.org/w/index.php?title=Wire-mesh_caul&action=edit&redlink=1) (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, and is limited by the equipment used. 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](https://en.wikipedia.org/wiki/Wikipedia: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. Individual panels are then cut from the mats into finished sizes. Most of the world's OSB is made in the United States and Canada in large production facilities.

## Related products

**Waferboard** belongs to the subset of reconstituted wood panel products called [flakeboards](/source/Flakeboard).[7] It is a structural material made from rectangular wood flakes of controlled length and thickness bonded together with waterproof [phenolic resin](/source/Phenolic_resin) under extreme heat and pressure. The layers of flakes are not oriented, which makes it easier to manufacture. Waferboard is used as a material to build cheap furniture. This type of furniture is usually laminated.

Materials other than wood have been used to produce products similar to OSB. [Oriented structural straw board](/source/Oriented_structural_straw_board) is an engineered board made by splitting straw and formed by adding P-MDI adhesives and then hot compressing layers of straw in specific orientations.[8] Strand board can also be made from [bagasse](/source/Bagasse).

## Production

In 2005, Canadian production was 10.5 million square metres (113 million square feet) (3⁄8 in or 9.5 mm basis) of which 8.78 million square metres (94.5 million square feet) were exported, almost entirely to the United States.[9] In 2014, [Romania](/source/Romania) became the largest OSB-exporting country in Europe, with 28% of the exports going to [Russia](/source/Russia) and 16% to [Ukraine](/source/Ukraine).[10]

## Properties

OSB, closeup of corner

Adjustments to the manufacturing process can affect thickness, panel size, [strength](/source/Strength_of_materials), and [rigidity](/source/Stiffness). OSB panels have no internal gaps or voids, and can be water-resistant, although they do require additional [membranes](/source/Artificial_membrane) to achieve impermeability to water and are not recommended for exterior use. The finished product has properties similar to [plywood](/source/Plywood), but is uniform and cheaper.[11] When tested to failure, OSB has a greater load-bearing capacity than milled wood panels.[12] It has replaced plywood in many environments, especially the North American structural panel market.

All wood-based structural use panels can be cut and installed with the same types of equipment as for solid wood.

### Health and safety

The resins used to create OSB have raised questions about their emission of [volatile organic compounds](/source/Volatile_organic_compounds) such as [formaldehyde](/source/Formaldehyde),[13] although industry trade groups assert that formaldehyde emissions from North American OSB are "negligible or nonexistent".[14] [Urea-formaldehyde](/source/Urea-formaldehyde_resin) is more toxic and should be avoided in home use. [Phenol-formaldehyde](/source/Phenol_formaldehyde_resin) products are considered to be relatively hazard free. Some newer types of OSB, so-called "new-generation" panels, use [isocyanate resins](/source/Isocyanate_resin) that contain no formaldehyde and are considered nonvolatile when cured.[15]

Some manufacturers treat the wood chips with various [borate](/source/Borate) compounds that are toxic to [termites](/source/Termite), wood-boring [beetles](/source/Beetle), [molds](/source/Mold_(fungus)), and [fungi](/source/Fungi), but not [mammals](/source/Mammal) in applied doses.

In 2024, a hotel in [Dublin](/source/Dublin), Ireland, lost its [fire safety certificate](/source/Fire_safety_certificate) after an inspection found fault with the composition of OSB in its flooring and walls.[16]

### Types

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

## See also

- [Medium-density fibreboard](/source/Medium-density_fibreboard), engineered board with much smaller flakes

## References

1. **[^](#cite_ref-1)** ["Dokument US000003164511A"](https://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&docid=US000003164511A) (PDF). *DEPATISnet*. Deutsches Patent- und Markenamt. [Archived](https://web.archive.org/web/20231213033059/https://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&docid=US000003164511A) from the original on 13 December 2023. Retrieved 2 May 2016.

1. ^ [***a***](#cite_ref-osb-info1_2-0) [***b***](#cite_ref-osb-info1_2-1) ["Technical Information"](https://web.archive.org/web/20160509234841/http://www.osb-info.org/technical.html). Osb-info.org. Archived from [the original](http://www.osb-info.org/technical.html) on 2016-05-09. Retrieved 2016-05-02.

1. **[^](#cite_ref-3)** Marotte, Bertrand (19 July 2016). ["Toronto's Norbord riding the rising wave of OSB sales"](https://beta.theglobeandmail.com/report-on-business/forest-products-firm-norbord-riding-the-rising-wave-of-osb-sales/article30985989/). *[The Globe and Mail](/source/The_Globe_and_Mail)*. [Archived](https://web.archive.org/web/20190812215615/https://beta.theglobeandmail.com/report-on-business/forest-products-firm-norbord-riding-the-rising-wave-of-osb-sales/article30985989/) from the original on 12 August 2019. Retrieved 20 September 2017.

1. **[^](#cite_ref-4)** Oldhand, Tony (25 Apr 2017), ["Types of Glue Used in OSB"](https://sciencing.com/types-glue-used-osb-8615640.html), *sciencing.com*, [archived](https://web.archive.org/web/20180801190656/https://sciencing.com/types-glue-used-osb-8615640.html) from the original on 1 August 2018, retrieved 1 August 2018

1. **[^](#cite_ref-5)** Koch, Peter (1985). *Utilization of hardwoods growing on southern pine sites*. Washington, DC: U.S. Dept. of Agriculture, Forest Service. p. 2423. [OCLC](/source/OCLC_(identifier)) [13459178](https://search.worldcat.org/oclc/13459178).

1. **[^](#cite_ref-6)** Hedges, Keith E. (2017). "Oriented Strand Board". *Architectural Graphic Standards* (12 ed.). Hoboken, NJ: [Wiley](/source/Wiley_(publisher)). [ISBN](/source/ISBN_(identifier)) [9781119312512](https://en.wikipedia.org/wiki/Special:BookSources/9781119312512).

1. **[^](#cite_ref-7)** ["AP-42: 10.6.1 Waferboard/Oriented Strandboard Manufacturing"](https://web.archive.org/web/20111216021325/http://www.epa.gov/ttnchie1/ap42/ch10/final/c10s06-1.pdf) (PDF). epa.gov. Archived from [the original](http://www.epa.gov/ttnchie1/ap42/ch10/final/c10s06-1.pdf) (PDF) on 2011-12-16. Retrieved 2013-10-08.

1. **[^](#cite_ref-8)** 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"](http://www.ncsu.edu/bioresources/BioRes_07/BioRes_07_3_2986_Han_CME_Zn_Borate_OS_Straw_Bd_Termite_Trial_2741.pdf) (PDF). *BioResources*. **7** (3): 2986–2995. [doi](/source/Doi_(identifier)):[10.15376/biores.7.3.2986-2995](https://doi.org/10.15376%2Fbiores.7.3.2986-2995). [Archived](https://web.archive.org/web/20151225074421/https://www.ncsu.edu/bioresources/BioRes_07/BioRes_07_3_2986_Han_CME_Zn_Borate_OS_Straw_Bd_Termite_Trial_2741.pdf) (PDF) from the original on 2015-12-25. Retrieved 2015-09-23.{{[cite journal](https://en.wikipedia.org/wiki/Template:Cite_journal)}}: CS1 maint: multiple names: authors list ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_multiple_names:_authors_list))

1. **[^](#cite_ref-9)** ["Review of the Canadian structural panel market"](http://www.fordaq.com/fordaq/news/Canadian_structural_panel_market_13586.html). Fordaq.com. 24 August 2006. [Archived](https://web.archive.org/web/20160406190234/http://www.fordaq.com/fordaq/news/Canadian_structural_panel_market_13586.html) from the original on 2016-04-06. Retrieved 2016-05-02.

1. **[^](#cite_ref-Fordaq_10-0)** ["Romania has become the largest OSB exporting country in the EU"](http://www.fordaq.com/fordaq/news/Romania_OSB_exports_EGGER_Kronospan_36635.html). *Fordaq*. Fordaq S.A. 7 April 2014. [Archived](https://web.archive.org/web/20160603054915/http://www.fordaq.com/fordaq/news/Romania_OSB_exports_EGGER_Kronospan_36635.html) from the original on 3 June 2016. Retrieved 1 August 2014.

1. **[^](#cite_ref-11)** ["UMass Amherst: Building and Construction Technology » Choosing Between Oriented Strandboard and Plywood"](http://www.umass.edu/bmatwt/publications/articles/osb_vs_plywood.html). Umass.edu. 2015-09-04. [Archived](https://web.archive.org/web/20090410144456/http://www.umass.edu/bmatwt/publications/articles/osb_vs_plywood.html) from the original on 2009-04-10. Retrieved 2016-05-02.

1. **[^](#cite_ref-12)** Chaya Kurtz (2010-05-12). ["Experts Talk About Engineered Wood - Articles"](http://www.networx.com/article/experts-talk-about-engineered-wood). Networx.com. [Archived](https://web.archive.org/web/20160601213122/http://www.networx.com/article/experts-talk-about-engineered-wood) from the original on 2016-06-01. Retrieved 2016-05-02.

1. **[^](#cite_ref-13)** [Mantanis, George I.](/source/George_Mantanis); 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](/source/Doi_(identifier)):[10.1080/17480272.2017.1396622](https://doi.org/10.1080%2F17480272.2017.1396622). [ISSN](/source/ISSN_(identifier)) [1748-0272](https://search.worldcat.org/issn/1748-0272).

1. **[^](#cite_ref-14)** ["Oriented Strand Board Educational Bulletin, Frequently Asked Questions"](https://web.archive.org/web/20160304041656/http://osbguide.tecotested.com/pdfs/en/el814.pdf) (PDF). *OSBGuide*. TECOTested.com. Archived from [the original](http://osbguide.tecotested.com/pdfs/en/el814.pdf) (PDF) on 4 March 2016. Retrieved 2 May 2016.

1. **[^](#cite_ref-15)** MacLeod, Ian. ["I'm concerned about toxic offgassing from OSB subflooring and roofing"](https://web.archive.org/web/20160605121604/http://www.greenhomeguide.com/askapro/question/i-m-concerned-about-toxic-offgassing-from-osb-subflooring-and-roofing-are-safer-products-available). *Green home guide*. Archived from [the original](http://www.greenhomeguide.com/askapro/question/i-m-concerned-about-toxic-offgassing-from-osb-subflooring-and-roofing-are-safer-products-available) on 2016-06-05. Retrieved 2015-11-14.

1. **[^](#cite_ref-16)** ["Operators of Dublin hotel with fire safety issues seeking order for €4.2m remedial works"](https://www.irishtimes.com/business/2025/11/03/dublin-hotel-potential-fire-danger-after-original-construction-issues-discovered/). *The Irish Times*. Dublin. 3 November 2025. [Archived](https://web.archive.org/web/20251103204932/https://www.irishtimes.com/business/2025/11/03/dublin-hotel-potential-fire-danger-after-original-construction-issues-discovered/) from the original on 3 November 2025. Retrieved 3 November 2025.

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Adapted from the Wikipedia article [Oriented strand board](https://en.wikipedia.org/wiki/Oriented_strand_board) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Oriented_strand_board?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.