Roof Sheathing Over Old

I have it under contract to resheath and reroof.

Roof sheathing over old.

This guide was developed and edited for old homes from original material in the u s. Attic ventilation comprises of a poorly installed ridge vent with no soffit vents. Walking on the roof feels very spongy. Because the plywood roof sheathing under the shingles has become brittle and weak he plans to install new plywood as well as new shingles.

The roof is sheathed with either 3 8 or 7 16 inch plywood. Over time shiplap fir wood resin dissipates causing the boards to shrink crack form knot holes and become extremely brittle. The contractor has asked if it is possible to leave the old sheathing in place and install the new 5 8 inch sheathing over the top of it. Roof sheathing the material nailed to your trusses or rafters to which your roofing is attached is your roof s workhorse.

The keyword here is solid it used to be standard to use shiplap 1 boards tongue groove or other boards for the roof deck. Roof shingles are to be replaced. Today a shiplap roof is usually 60 years old. Question 1 which is preferable from a quality perspective cost is secondary.

Sheathing is installed over multiple trusses rafters so it essentially turns them into one cohesive unit instead of individual structural members. Two questions about replacement of roof sheathing. Roof sheathing provides an area where the surface material can be attached but it also helps keep the trusses and or rafters properly spaced. But can he simply install new plywood over the old.

There does not appear to be any roof leaks but from poking at the sheathing from below there appears to be dry rot. Sheathing works with other components of the roof as well. It is now warped and wavy. 50 year old house with 3 8 plywood sheathing on trusses spaced at 24.

As roofing contractors in seattle we are often asked why do we need plywood over our old solid sheathing. It is in your best interest to apply solid sheathing over the existing shiplap for your roofing system to securely fasten to.