Roofing Do You Need To Use Treated Plywood

Where to use pressure treated wood while many homeowners wonder if they should use pressure treated wood for a specific project the answer is simple.

Roofing do you need to use treated plywood.

For rafters spaced 20 or more inches apart 1 2 or 5 8 inch plywood is recommended. Perry mastrovito design pics getty images. Note that this requirement is only for exterior walls as these may wick moisture onto the lumber. The most common rafter spacing is 24 inches and 5 8 inch plywood is recommended for that.

If plywood is not dealt with properly it can swell and create major problems with roofing flooring or siding. Interior walls are within a climate controlled environment and are presumed to be free of moisture. The sawdust from pressure treated wood is an irritant to the eyes skin and nose. It will support roof.

Osb and plywood come in thicknesses ranging from 5 16 to 3 4 inch and the thickness needed for a particular roof depends on several factors including rafter spacing expected load and roof design. Use pressure treated wood in any situation where there s direct contact between the wood and anything that could supply moisture. These tips cover plywood characteristics and proper installation of plywood. I do remember decades ago when us steel and kaiser aluminum were big metal panel roofing suppliers and aca cca which are salts treated wood was first commonly available they did recommend but not insist for warranty coverage that narrow strips of roofing felt be put across the top of the firring strips to avoid direct contact and possible corrosion.

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. While metal roofing doesn t require plywood underlayment there are circumstances in which you may wish to install plywood to anticipate future roofing needs or to offer additional soundproofing. Moisture causes wood to rot and rotten wood absorbs water even more readily than fresh wood. Wood for indoor projects should be left as is.

This means posts in contact or buried underground obviously but it also includes any lumber touching concrete or masonry since it s porous and wicks water like a sponge. Wood for any outdoor project should be pressure treated. Modern metal roofs are expected to last 30 years or longer. If there is rotten decking the shingles are most likely letting moisture in.