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What are the roof sheathing requirements for a roof replacement in Florida?
Monday, August 6, 2018
When you replace a roof on a home that was built before the implementation of the statewide Florida Building Code on March 1, 2002, the nailing of the roof sheathing (decking) must be brought up to current standards for hurricane resistance as part of the installation of the new roof. The requirement became effective on October 1, 2007.
The roof sheathing (plywood or OSB) has to be be nailed with 8D (eight penny) ring-shank round head nails at six inches on center. If it was originally secured using staples or 6D nails, it must be completely re-nailed to the new standard. In wind zones of 110 mph or less (such as Alachua County), if the roof was secured with 8D nails (but not ring-shank) at a lesser spacing, additional ring-shank round head nails must be added where necessary to meet the six-inch spacing. Wind zones of 120 mph and up require complete re-nailing if the existing 8D nails are not ring-shank.
A home inspector doing a wind mitigation form for insurance verifies the 8d ring-shank nail by looking for a “shiner”—a nail that missed the top of the truss or rafter. There’s always one or two around the attic. An 8d nail is 2.5” long and protrudes though the roof sheathing a little less than 2”, as shown below.
Your contractor must fill out and sign an affidavit stating that the roof deck upgrade requirements have been met and submit it to the local building department as part of the requirements for a final roof inspection. They only apply for “roof replacement,” where the previous roof is completely removed down to the sheathing. If your roofing contractor is doing a “reroof,” which is where the new roof is applied over the existing roof, the upgrade of the sheathing is not required. But it’s just a one-time reprieve. When you need a new roof again, it all has to come off and the sheathing upgrade done, because you are only allowed to reroof over one layer of roofing.
Also see our blog posts When did Florida start requiring re-nailing of roof deck sheathing for a roof replacement? and What are the different roof deck attachment discount categories for a wind mitigation inspection? and When did the Florida code start requiring roof sheathing nails to be ring-shank instead of smooth? and How can I find out the age of a roof?
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To learn more about roofs and attics, see these other blog posts:
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