Plywood Over Shiplap Roof

Shiplap doesn t have any gaps in the boards and can be roofed over as is usually.

Plywood over shiplap roof.

Thanks for the heads up. Open spaces form between the once tightly fitted shiplap boards. Shiplap roof decking was widely used in the 50 through 80 s era when plywood hadn t yet made its way into new construction. If it is a hot roof and the design assumes airtight sheathing it would be easy at this point to install plywood zip sheathing and tape it.

Shiplap is now considered an enemy of asphalt shingles. Today a shiplap roof is usually 60 years old. At one point in time it was standard to use shiplap tongue and groove one inch boards or other boards for your roofing deck. There is another issue whether the shiplap is aiding your household air infiltration.

In most cases if it is a cold roof shiplap will be fine. The shiplap does look like its in good condition however i haven t put nails into it or given it any other test of strength. I was low balling it to see if indeed as the roofer said low slopes necessitate adding plywood over shiplap. If you have roofers that don t know the difference between shiplap skip sheathing find a roofer that does.

Over time shiplap fir wood resin dissipates causing the boards to shrink crack form knot holes and become extremely brittle. After the 1960s the predominant residential roofing substrate became 1 2 cdx plywood. Whenever your roof was first installed the nails were put into the solid wood. As for slope i haven t actually measured it.

I m building a solid patio roof and was planning on using 1 2 plywood over the rafters 24 oc for the roof with spruce shiplap over the eaves to match existing house look. Being ideal for asphalt shingles in the early days of its creation shiplap sits beneath the roof of many homes about thirty years old. These 8 to 12 inch wide boards were nailed together tight. I am sure i am not the only one that has been deceived by what looked like venting but wasn t.

The keyword here is solid it used to be standard to use shiplap 1 boards tongue groove or other boards for the roof deck. These wider boards were all nailed tightly together. Plywood will eliminate the buckling problem completely but still needs to be properly vented. Shiplap does work but requires good intake exhaust.

As roofing contractors in seattle we are often asked why do we need plywood over our old solid sheathing. Remember the keyword is solid. Sometimes on older houses they have had so many different roofs that the deck is all shot up splintering in this case a redeck is in order.