Madison Roofing: Article About Plywood Roofing
Oriented Strand Board, or OSB, as it is more commonly called, is plywood's greatest rival in the home construction market. OSB is used more than any other material for wall sheathing and floor underlayment. However, many Madison roofing contractors do not recommend OSB for the roof decking of their client's homes. They recommend plywood instead.
OSB is engineered wood made of shredded, long strands of wood that have been bonded together with resins, heat and pressure. Plywood, on the other hand, is made of several layers of wood that are glued together. Plywood is very durable and flexible, but can cost as much as $5 more per sheet than OSB.
One of the reasons for OSB's huge surge in popularity is because it is cheaper. Due to its lower cost, it can cut the price of the average house by approximately $700 to $1000.
Another reason OSB has become such a favored building material is because it is made from several fast growing species of trees. These trees are grown on farms and harvested when young, eliminating the need to deforest large areas for older, lumber producing trees.
The roofing contractors at Hustad Companies of Madison can assist you with any questions regarding commercial roofing or windows.
OSB can be made into much larger sheets than plywood, which is better for large building applications. OSB is denser and more uniform in structure and appearance, and there are no knotholes or cracking in the surface. Also, OSB does not warp like wood does.
However, OSB board is not superior to plywood in regards to resisting the effects of moisture. The constant presence of moisture on a roof from rain and snow is a very important factor to consider when choosing the best materials for a roof. OSB will swell with water just like plywood, but will not return to its original dimensions like the plywood. The OSB will remain swollen even when completely dry, especially along the edges. These swollen edges will cause ridges to appear under the shingles, marring the smooth appearance of the roof. The potential problem with moisture and swelling is the main reason experienced professional roofers do not like to use OSB board as roof decking.
Another problem with moisture is that OSB has a tendency to stay wet longer than wood, encouraging rot of the roof decking. In addition, Madison contractors report the OSB board has an unfortunate tendency to sag between the rafters or trusses, giving the roof an undulating or wavy look that is not smooth or attractive.