2 Layers Of Plywood On Roof

The deck is not rotting out except for a few spots along the drip edge which we are cutting out to replace.

2 layers of plywood on roof.

This particular type of plywood is crafted from layers of wood stacked on top of one another with alternating grain patterns in each layer. Even though 2 roof layers are legal we do not like covering over any old roofing materials with another layer because we don t believe in covering up problems. 2000 sf of 1 2 cdx ply went on the roof before i had a chance to take a look at it and it is really sorry stuff. The alternating grain gives the plywood a system of checks and balances that allow it to expand and contract evenly across the sheet.

But unlike an asphalt shingle roof. The attic was well vented with gable vents so i dont think it is a heat issue. The roof deck turned out to be 3 8 plywood which is starting to break down due to the number of times the roof has been replaced. Can you double up plywood roof sheathing without inviting disaster.

Every house in the neighborhood is being redone and havent seen any other 40 contractors in the neighborhood doing all the plywood installation. It got nailed over 2 x 12 joists 24 o c. And plywood or osb roof decking thus ultimately into the attic space. Wood structural panel sheathing or siding used to resist combined shear uplift.

On 4 12 or greater slopes the balance of the roof shall be one layer of 15 felt. 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. Both osb and plywood for the roof have been approved for use so it. It is typically made in 4 by 8 foot sheets although longer panels are available for special purposes.

On roof slopes of 2 12 to 4 12 the remainder of the roof shall be two layers of 15 felt applied in shingle fashion or 1 layer of ice dam protection. 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. Also was the plywood in 1960 defective. The roof in question is my neighbors roof i just had seen the contractor putting the second layer of plywood on over the tarpaper and thought it was kind of strange so i thought i would ask.

I urge you to remove both layers of roofing so that the new roof investment will last as long as its intended to and that you have peace of mind that your roof is sound from top to bottom inside and out. The main issues are that you can hear the plywood cracking and feel it give under you as you walk around.