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Roofing Plywood Repairs

Posted by WhiteKnight on

Plywood Repair for Roofing

There you are in the attic putting away another box of stuff. You don’t know what to do with it, so for now it goes in the attic until you figure out what to do with it. You happen to look up and you notice the bottom side of the plywood decking is discolored from water stain and some of it is rotting. How bad is this? And what should I do about it?

There are a number of reasons how the plywood could have gotten wet. A thunder storm with high winds may have loosened some of the shingles and allowed rain to be blown up under the shingles.  A tree limb may have fallen on the roof causing damage to the shingles and decking. Or the roof may have just gotten old and deteriorated. It may have simply reached its life span.  Unfortunately all of these reasons lead to a costly roofing repair job.

To repair the damaged plywood ( or OSB ) you must first determine how much of the plywood is damaged, and how much that you want replace. Be sure you plan to replace all the damaged plywood. Otherwise you will probably be repeating your repair job again as the part of the plywood that you didn’t replace continues to rot. Remove the shingles in the damaged area by lifting one shingle at a time and rocking it back and forth while pulling down until it releases. You will have to determine how many shingles you need to remove in order to replace however much of the plywood you want to remove and replace.

Next you will need to remove the nails with a pry bar. There will be some nails under the top row of shingles that you will need to gently remove without damaging them.  A flat pry flat pry bar should be used rather than a hammer. Next remove the underlayment. The underlayment should be easily removed since it is being held down by only a few nails with plastic caps.

Now you are ready to remove the old damaged plywood. Remove the nails holding the plywood in place with a hammer and pry bar. Being careful not to loose your footing lift the old plywood out and place it safely away from your work area. Next cut your new plywood, if necessary, to fit the opening and securely nail it down. Once the plywood has been installed replace your underlayment using roofing nails with nail caps.

Now it’s time to replace your shingles. Start at the bottom and work your way up fitting each shingle in place covering up the row of nails below it. Use 6 nails per shingles to insure the shingle will hold. The last row of old shingles will need to be held up so the last row of new shingles will fit up under them. Once the last row of new shingles has been nailed down apply a dab of roofing caulk over each nail and then lay old shingles back down over them.

And there you are. A job well done. Now get back to filling that attic up with more stuff.