2 Layers Of Plywood On Roof

On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing.

2 layers of plywood on roof. It is typically made in 4 by 8 foot sheets although longer panels are available for special purposes. However 3 4 th inch plywood is also used for a roofing system that has a heavier load. This particular type of plywood is crafted from layers of wood stacked on top of one another with alternating grain patterns in each layer. For the less standard 20 inch apart rafters plywood with inch or 5 8 th inch thickness can be used.

Roof deck is the roofing material that sits on top of the roof trusses. 3 8 plywood roof sheathing. Steep sloped roof products such as tile slate metal and shakes only allow one layer. Most roof decking is made from sheets of plywood.

Nailing new shingles over existing ones is less expensive and faster requiring less labor but it also means you lose the chance to assess the sheathing for signs of water damage. Asphalt shingles typically can have one more layer added over the top two roofs total. Also was the plywood in 1960 defective. Most roof decking is made from sheets of plywood.

For many years it was acceptable to put even the third layer. Wood structural panel sheathing or siding used to resist combined shear uplift. The main issues are that you can hear the plywood cracking and feel it give under you as you walk around. Plywood is made with three or more layers of thin wood glued together with the grain alternating.

Water shield is the next roofing layer that creates a water proof barrier where ice or water can buildup near the roof eaves. Both osb and plywood for the roof have been approved for use so it. The deck is not rotting out except for a few spots along the drip edge which we are cutting out to replace. The alternating grain gives the plywood a system of checks and balances that allow it to expand and contract evenly across the sheet.

Most building codes allow for two layers of asphalt shingles on a house so stripping off everything down to the plywood sheathing may not be your only choice.