Plywood Over Shiplap Roof

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.

Plywood over shiplap roof.

As for slope i haven t actually measured it. 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. Open spaces form between the once tightly fitted shiplap boards. Being ideal for asphalt shingles in the early days of its creation shiplap sits beneath the roof of many homes about thirty years old.

Plywood will eliminate the buckling problem completely but still needs to be properly vented. However that isn t the case. In most cases if it is a cold roof shiplap will be fine. The keyword here is solid it used to be standard to use shiplap 1 boards tongue groove or other boards for the roof deck.

After the 1960s the predominant residential roofing substrate became 1 2 cdx plywood. I am sure i am not the only one that has been deceived by what looked like venting but wasn t. Thanks for the heads up. But since the rafters will be open this plywood will be visible from the patio.

At one point in time it was standard to use shiplap tongue and groove one inch boards or other boards for your roofing deck. These wider boards were all nailed tightly together. Shiplap is now considered an enemy of asphalt shingles. Whenever your roof was first installed the nails were put into the solid wood.

There is another issue whether the shiplap is aiding your household air infiltration. Shiplap roof decking was widely used in the 50 through 80 s era when plywood hadn t yet made its way into new construction. Remember the keyword is solid. 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. 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. Today a shiplap roof is usually 60 years old.

These 8 to 12 inch wide boards were nailed together tight. Shiplap doesn t have any gaps in the boards and can be roofed over as is usually. If the roofing underlayment is applied directly on top of the shiplap it will sag into the spaces and eventually leak.