High-Wind Nailing Deficiencies on a New Hip Roof
Your crew is installing 5,200 sq ft of laminated architectural shingles on a new 6/12 hip roof designed for a 115 mph basic wind speed. The manufacturer's printed instructions require six nails per shingle for this wind zone and specify 12-gauge, 1¼-inch roofing nails with 3/8-inch heads. The crew is using pneumatic coil nailers set at 110 psi. During a mid-morning inspection you find that the first 12 squares have four nails per shingle, many nails are driven so deep that the nail heads cut into the shingle mat, and some nails are placed 2 inches above the exposure line. Several nails protrude through the 7/16-inch OSB deck. The crew says the coil nails are 1¼ inch and that the gun pressure is 'what we always use.' The starter course is made from inverted three-tab shingles, and hip and ridge caps are being nailed with two nails per cap.
1. Identify the nonconformances and explain why each one matters in a 115 mph wind zone.
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The primary nonconformance is four nails per shingle where the manufacturer requires six. Wind uplift loads are transferred through the fasteners, and missing nails reduce both withdrawal resistance and the shingle's ability to resist peeling from the eave and rake. The second is high nailing: nails placed 2 inches above the exposure line are outside the manufacturer's nail zone, so the shingle can lift and tear around the nail instead of being held at the bond line. The third is overdriving. Nails driven through the mat cut the reinforcement and create a path for tear-out; adding another nail nearby does not restore the damaged shingle.
The protruding nails through 7/16-inch OSB are not automatically a defect if the nails achieve full penetration through the deck and the heads seat properly, but they are a warning sign that depth control is poor. The inverted three-tab starter and two-nail hip/ridge pattern must be checked against the same manufacturer's instructions: some allow an inverted starter, many require a proprietary starter strip, and high-wind details may require more fasteners at hips and ridges. Any deviation from the printed instructions is a potential wind-warranty and code issue.
2. What corrective action should you take before the roof is closed in?
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Stop production and inspect the installed area methodically. For shingles with cut mats or overdriven nails, remove and replace them with new shingles; do not simply drive a second nail through the face. For shingles with only missing nails and an intact mat, add the required nails in the manufacturer's nail zone if the manufacturer permits supplemental fastening. Set the nailer depth and pressure using a test board or scrap deck, then verify that heads are flush with the shingle surface, not below it, and that nails are in the nail line.
Retrain the crew on the six-nail pattern and the nail zone, and assign one person to check each completed square before the next course covers it. Replace the inverted starter if it is not an approved method, and confirm the hip/ridge fastening schedule. Document the corrections with photographs and a written punch list. Because the roof is still open, this is the cheapest time to fix the work; after the ridge caps are installed, the same defects are much harder to find and much more expensive to correct.
3. How would you explain the wind-uplift mechanism to the crew so the fix sticks?
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Use a simple load-path explanation. Wind flowing over the roof creates negative pressure that tries to lift the shingle from the eave upward. The sealant strip bonds the shingle to the course below, but before the sealant cures or when it is cold, the nails carry the load. Six nails spread that load across the shingle; four nails concentrate it and allow the shingle to flex and peel. A nail placed high above the exposure line gives the shingle a long lever arm to tear around the head, and an overdriven nail cuts the mat so the shingle fails at the hole.
Show them a failed shingle from a previous job if available, or demonstrate on scrap: drive one nail correctly, one high, and one overdriven, then pull or flex the shingle. Explain that the manufacturer's wind warranty is conditional on the fastening pattern, so the crew's speed today creates callbacks and claim denials later. Post the nail pattern at the staging area and make the depth check part of the morning setup, not an after-the-fact correction.