Tip of the Month

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December 2009

How should new roof sheathing be installed?

When a cedar shake roof is removed and replaced with composition shingles, new solid panel roof sheathing is typically installed over the existing spaced plank sheathing. Regrettably many roofers fail miserably to install new sheathing properly and when sheathing is not installed properly it will most often buckle-up over the years to come. To avoid unsightly sheathing problems, quiz the contractor you are considering for the job to see if they know how sheathing should be installed & see if they propose to have the sheathing installed properly "before" you select your contractor! Per building code when OSB (oriented strand board) or plywood sheathing is installed over spaced sheathing the following guidelines are to be followed: *Ends of sheathing are to be fully supported by the structural framing (i.e. ends of sheathing must align with the rafters, not terminate between rafters). *Sheathing is to be fastened with a minimum of 8D common nails. *Fasteners are to be spaced at a maximum of 6-inches on center at supported ends and edges. *Sheathing is to be fastened at intermediate supports a maximum of 12-inches on center. *A 1/8-inch space is to be maintained between sheets at all ends and edges of sheathing to allow for expansion and contraction of sheathing. *New sheathing is to be fastened to the rafters with fasteners of sufficient length (equivalent to that designated per International Residential Code Table R602.3) to pentrate into structural framing adequately. If not fastened properly new roof sheathing could buckle or could lift completely off of the underlying spaced sheathing in high winds. Worst of all, problems attributable to poorly installed sheathing seldom become apparent until several years have passed. Once the problem does become apparent the warranty has typically expired & the contractor is often unwilling to correct the problem. Installing roof sheathing correctly is just one of the many aspects of roof installation that Larry Vaught Roofing routinely provides. And from what we have observed during our 42+ years in business, there simply aren't many companies that truly pay as close attention to detail as Larry Vaught Roofing does. If in doubt, just ask a contractor what they know about sheathing installation & you just might discover you know more than they do after simply reading our December Tip of the Month!