Plywood Over Plank Roof

Take time to make sure your existing planks are well secured in place.

Plywood over plank roof.

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. Today a shiplap roof is usually 60 years old. The issue guertin explains is the gaps between boards. Install a layer of at least or preferably 5 8 ply over the existing planks.

In the first half of the 20th century roofs in missouri were built with wood shingles over planks spaced about 1 apart. Personally i like plank spaced decking. Plywood used for roof decking is typically called sheathing and carries a grade stamp indicating its load and span ratings and other performance factors. 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.

Its really common here too to see 3 8 plywood used on roofs from the 70 s. Plank sheathing usually 1 6 or 1 8 was used as a roof deck before plywood. After the 1960s the predominant residential roofing substrate became 1 2 cdx plywood. Most western washington residential homes during this time were built with shiplap roof decks rather than plywood.

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. On older homes planks were often spaced for wood or slate roofs with wider exposures than the standard 5 inch tab on asphalt shingles. Over time shiplap fir wood resin dissipates causing the boards to shrink crack form knot holes and become extremely brittle. Repair any broken planks.

This is particularly important if your old sub floor has lumps and bumps in it. In that case they could whe replacing shingles fill the larger gaps with firring. Use decking screws to secure squeaking planks through 1 4 ply to joists. The keyword here is solid it used to be standard to use shiplap 1 boards tongue groove or other boards for the roof deck.

Things to take into account when laying ply over plank subfloors. These 8 to 12 inch wide boards were nailed together tight. As roofing contractors in seattle we are often asked why do we need plywood over our old solid sheathing. Or they could place osb or plywood over current planking.

Plywood is layers of wood plywood is made. But the spacing should not be more than quarter inch.