Plywood Over Plank Roof

Use decking screws to secure squeaking planks through 1 4 ply to joists.

Plywood over plank roof.

But the spacing should not be more than quarter inch. Over time shiplap fir wood resin dissipates causing the boards to shrink crack form knot holes and become extremely brittle. We resheet with 1 2 osb right over top of the old all the time be it 3 8 ply or old t g boards in the case of the old t g boards it makes for a flatter surface plus greatly lessons the chance of nailing into the gap between boards. Plywood is layers of wood plywood is made.

As roofing contractors in seattle we are often asked why do we need plywood over our old solid sheathing. Take time to make sure your existing planks are well secured in place. Plywood used for roof decking is typically called sheathing and carries a grade stamp indicating its load and span ratings and other performance factors. Things to take into account when laying ply over plank subfloors.

Personally i like plank spaced decking. The keyword here is solid it used to be standard to use shiplap 1 boards tongue groove or other boards for the roof deck. Install a layer of at least or preferably 5 8 ply over the existing planks. Why re sheet over shiplap.

Its really common here too to see 3 8 plywood used on roofs from the 70 s. In the first half of the 20th century roofs in missouri were built with wood shingles over planks spaced about 1 apart. On older homes planks were often spaced for wood or slate roofs with wider exposures than the standard 5 inch tab on asphalt shingles. After the 1960s the predominant residential roofing substrate became 1 2 cdx plywood.

This is particularly important if your old sub floor has lumps and bumps in it. It was common practice to have a clause in the contract that once the roof was stripped down depending on what was found plank roofs that were not already covered with plywood would then need to be covered in order to do a good job and provide a solid warranty. Plank sheathing usually 1 6 or 1 8 was used as a roof deck before plywood. Use door skins to raise dips to 1 8 use contact cement to secure to existing 1 4 ply secure 17 32 plywood to the planks with 1 5 deck screws avoiding the joists to allow slip install engineered hardwood over the new subfloor w underlayment if needed.

The issue guertin explains is the gaps between boards. These 8 to 12 inch wide boards were nailed together tight. Open spaces form between the once tightly fitted shiplap boards. Most western washington residential homes during this time were built with shiplap roof decks rather than plywood.

Today a shiplap roof is usually 60 years old. In that case they could whe replacing shingles fill the larger gaps with firring.