Replacing Roof Boards Plywood

Screw the rafter to the chimney cleat as well.

Replacing roof boards plywood.

Cdx plywood is a construction grade type of plywood that is designed for exposure to the elements. Rotted plywood cannot support the weight of a roof the way healthy wood can nor can it safely grip the nails put into the roof and keep them held firm. As roofing contractors in seattle we are often asked why do we need plywood over our old solid sheathing. Moisture causes wood to rot and rotten wood absorbs water even more readily than fresh wood.

Clamp a 1 by backing board in place and screw the new rafter to it. Most construction sites will consider the use of either osb or plywood for the roof. Today a shiplap roof is usually 60 years old. Open spaces form between the once tightly fitted shiplap boards.

Now it s time to replace the roof plywood and any other damaged wood in the roof area. These 8 to 12 inch wide boards were nailed together tight. The keyword here is solid it used to be standard to use shiplap 1 boards tongue groove or other boards for the roof deck. Make minor repairs on the roof if it is in good condition.

Protect the edges of the plywood soffit from water penetration with a waxy sealer such as anchorseal. If not replace bad wood with new plywood sheathing or 1 x 6 sheathing boards whichever is applicable to your type of roof. Select plywood or oriented strand board that is the same thickness as the wood you are replacing. Over time shiplap fir wood resin dissipates causing the boards to shrink crack form knot holes and become extremely brittle.

If not climb the roof and measure the opening so you can cut the replacement piece to be a perfect fit. Rotted plywood can cause a number of issues. I ll be on the road for a few months and won t have time to complete these posts until after but for those of you who ve written wanting to see the rest of the project hopefully this is better than nothing. The tear off gets a lot more complicated if you have something other than asphalt up there.

If you were able to keep the removed section in one piece measure it. If you can see original wood shingles on the underside of your roof when you re up in the attic you ll need not only to tear everything off but also to install new plywood decking all of which likely adds 5 000 or more to your costs. After the 1960s the predominant residential roofing substrate became 1 2 cdx plywood.