After a tear-off is done on your roof, you’re left with bare decking and all the original wood is exposed. The next thing that needs to happen is a thorough roof deck inspection to check the plywood for potential problems. Skipping this step could mean losing big money down the road if there is a plywood failure.
DANGERS OF NOT DOING A ROOF DECK INSPECTION
Your new roof will be attached with thousands of nails to your roof decking. Plus it will hold the weight of the roofing, roofers walking around, and any snow that accumulates in the winter. If there is even one point of plywood failure it will be very expensive to fix, especially when compared to the cost of replacing when the roof is torn off.
If the plywood is de-laminated or compromised in some way, the nails used to hold the roofing on will not stay in the damaged wood. Instead, they will start to back out and ruin the shingles above. Then, since the shingles aren’t attached well, they are at risk of blowing off and leaving the roof exposed for damage to occur.
To repair this kind of thing, a big area of shingles have to be removed. usually at least 50 sq. ft. depending on the size of damaged plywood found. Obviously if your entire roof decking failed and started having problems like this even 4 years after your roof was replaced, you would need to get your entire roof replaced again. There’s no other way to get at the plywood than to remove the roofing.
WHAT NEEDS TO BE CHECKED DURING A ROOF DECK INSPECTION?
During the deck inspection every square foot of the plywood needs checked for problems. These problems could show up in the form of water damage, dry rot, de-lamination (if plywood), cupping (if ship-lap or 1 inch boards), and general damage. Roofing over any of these problems is asking for trouble later on in your home’s life.
Other places that should be checked during this inspection is anywhere there was flashing installed. At this point all your wall flashings should be removed so you can get a good look at everything.
After the inspection is done, any damaged or compromised plywood needs to be replaced to make the deck strong and ready for the installation of shingles. When replacing plywood, new pieces should never be smaller than half of a sheet of plywood (4’x4′). If just a 2’x4′ area is replaced it makes that spot weak since it’s not spanning across a truss.
Because a thorough roof deck inspection is so important, be sure that the roofing contractor you hire says he will do one (in writing!). If not, he may just blast through your project and you could be left holding the bag a few years down the road. REMEMBER: A “workmanship warranty” is only going to cover things that the contractor said he would do in writing, if there’s no mention of it, you can’t go after him for not checking.