Jan 31 , 2019
Plywood vs OSB
There is often a debate on which is better- plywood or oriented strand board (OSB). Both can be used in structural applications for roofs, walls and floors. Let’s take a look at which one might be the better choice for you and your projects.
OSB is more resistant to moisture absorption but also takes longer to dry out. When OSB gets wet for extend periods of time the edges swell and can telegraph through materials that will later be installed over it. This problem occurs most often on roofs and flooring and can lead to production delays as well as additional costs for sanding or material replacement. Being diligent in keeping material dry prior to installation and getting it covered as soon as possible can help mitigate these issues.
Plywood absorbs moisture faster but also dries out much faster, but extended moisture exposure can cause plywood to delaminate. Both materials have an exposure rating that should allow them to survive the normal time it takes to get a project buttoned up. Because subfloor doesn’t shed water like sheathing or roof decking, it is most susceptible to water. Specialty panels that can be exposed for long periods of time are probably the best solution for rainy regions of the country.
From a structural perspective OSB and plywood sheathing are comparable. The Engineered Wood Association (APA) doesn’t really distinguish between these two materials in most structural applications and building codes generally recognizes the two as the same. When tile or hardwood flooring is to be installed over the subfloor, plywood may be a better choice. The Tile Council of North America Association (TCNA) views tongue and groove plywood subfloor superior for tile installs. When hardwood flooring is the choice, some of the previously discussed moisture issues can come into play with OSB. Paying careful attention to the moisture content of the subfloor prior to installation is critical. When the differential is too high it can cause the flooring to cup or buckle.
Each of the two materials have advantages when it comes down to actually working with it. Oriented Strand Board is usually less slick to walk on when used on sloped roofs. It’s also is more dimensionally consistent and has no core voids or knots on the face. Plywood is a bit stiffer and lighter than OSB and less prone to dishing out nasty splinters.
Price is always a consideration when selecting which building material to use. OSB is generally less expensive than its plywood counterparts. This can make a significant difference in the final cost of a large addition or new home. Plywood is generally perceived as a higher-quality building material by many consumers and can play a roll in the overall satisfaction of a job by a savvy client.
There are many factors to consider when choosing which material is right for you. At the end of the day it may come down to personal preference, regional or trade norms.
Brian Carpenter has been involved in the construction industry for over 15 years, in the field and through material distribution and sales. He has had the opportunity to work with and learn from many different trades and manufacturers over the years.