Osb Vs Plywood For Shed Roof

2x greater shear strength than similar sized plywood source.

Osb vs plywood for shed roof.

The lower the slope the more weight for snow load but less wind force. While a sheet of plywood might be 5 to 7 plies thick a sheet of osb is made from as many as 50 strand layers packed and compressed into the same thickness. Osb is now used for about 70 percent of all floor wall and roof sheathing in north america. Osb is made by combining glue resin and wood chips and pressing them into the shape of a plywood sheet then baking everything together.

Secondly osb panels have a higher shear rating than plywood panels and are thus often installed with greater spans than plywood of the same thickness. Both cdx plywood and osb tend to come in standard sheets of four foot by eight foot 4 8. This can result in visible deflection of the panels between the supports and can telegraph through causing a wavy appearance to the roof. Building codes the engineered wood association architects and most builders rate plywood and oriented strand board obs sheathing equal in strength and durability.

Compared to cdx oriented strand board osb is made very differently. Oriented strand board isn t plywood nor is it a type of particleboard fiberboard or wafer board and although it is a newcomer to a plywood dominated market its use for exterior sheathing is. Osb boasts a more consistent density. However you might find that osb can better suit your needs than plywood for the roof.

University of massachusetts meets most building codes for roof and wall sheathing. Plywood is better than osb for subfloors. New homes will usually see a few rainfalls before a roof is on and as noted above osb doesn t handle moisture well. Because of this manufacturing process osb is at least half the cost of cdx plywood.

Even though plywood is more expensive and osb stronger my recommendation for a shed roof is 5 8 or 3 4 construction grade exterior rated cdx t g plywood. The higher the slope the more quickly the snow and rain will be shed but also the greater the wind force. Because of its construction some manufacturers actually make larger sheets of osb. Today you can find osb in thickness from 7 16 to 1 1 8 for different applications from roof wall subfloor i joists and everything between.