Roof Sheathing Over Old

As roofing contractors in seattle we are often asked why do we need plywood over our old solid sheathing.

Roof sheathing over old.

50 year old house with 3 8 plywood sheathing on trusses spaced at 24. It is in your best interest to apply solid sheathing over the existing shiplap for your roofing system to securely fasten to. 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. Question 1 which is preferable from a quality perspective cost is secondary.

Because the plywood roof sheathing under the shingles has become brittle and weak he plans to install new plywood as well as new shingles. Over time shiplap fir wood resin dissipates causing the boards to shrink crack form knot holes and become extremely brittle. But can he simply install new plywood over the old. Attic ventilation comprises of a poorly installed ridge vent with no soffit vents.

Roof sheathing the material nailed to your trusses or rafters to which your roofing is attached is your roof s workhorse. The anchor of the system that keeps. Apply new roof sheathing osb directly over old sheathing sagging inch plywood or rip the old sheathing off and apply new sheathing to the trusses. The roof is sheathed with either 3 8 or 7 16 inch plywood.

This guide was developed and edited for old homes from original material in the u s. Walking on the roof feels very spongy. Today a shiplap roof is usually 60 years old. Sheathing is installed over multiple trusses rafters so it essentially turns them into one cohesive unit instead of individual structural members.

Housing and urban development hud rehab guide. It is now warped and wavy. Roof sheathing provides an area where the surface material can be attached but it also helps keep the trusses and or rafters properly spaced. Two questions about replacement of roof sheathing.

I have it under contract to resheath and reroof. The keyword here is solid it used to be standard to use shiplap 1 boards tongue groove or other boards for the roof deck.