Dallas Roofing: Article About Plywood VS Oriented Strand Board (OSB)
When a homeowner compares two roofing bids, one might list plywood as the decking substrate while another might list oriented strand board. This minor different can make a significant difference to the roofing quote since oriented strand board can cost up to $3 less per sheet. Dallas roofing experts should be able to explain the pros and cons of both products to a homeowner's satisfaction.
Plywood is made of multiple sheets of thin wood (or plies) that are glued together. Each layer of plywood is rotated between 45 and 90 degrees, altering the direction of the grain. This is what gives plywood its strength. The cross-graining makes plywood less likely to warp, expand or shrink under normal weather conditions and makes it less likely to split when nailed around the edges.
Oriented Strand Board is a wood particleboard created by compressing layers of wood strips and adhesive. OSB derives its strength from layering as well. With OSB, the outside layers have the board have wood stripes that run along the board's axis while the internal layer has strips running perpendicular.
The roofing companies experts at Total Roofing of Dallas can assist you with any questions regarding residential roofing or roof maintenance.
Although some homeowners prefer plywood simply because it looks more like wood and some contractors insist that OSB sags over time, the use of OSB for flooring, walls, and decking is far outpacing that of plywood. No doubt, that is due to the lower price and the advantages of OSB.
OSB panels are water resistant since they have no internal gaps or voids. Where plywood may have up to 5 or 7 plies, OSB can be up to 50 strand layers compressed to the same thickness. However, water resistant is not waterproof. To truly protect OSB, a waterproof membrane needs to be added. In fact, prolonged moisture exposure is where plywood out preforms. Although OSB is slower to absorb water, it is also slower to dry. This can be a problem during construction or if the roof develops a leak. OSB will be more prone to decomposition due to water damage.
Plywood also has a slight advantage when it comes to stiffness. Because knotting in the veneer plies in each panel can cause weak spots, plywood is often overbuilt to accommodate any of these weaknesses. This makes plywood about 7 percent stiffer than OSB. Plywood is also lighter than a similar size OSB since OSB undergoes so much wood flake compression.
In the final analysis, it comes down to a personal choice. Both plywood and OSB have the same exposure durability for interiors (Exposure 1) and for exteriors (Exposure 2), and both share the same performance standards and span ratings.