Concrete Tile Uplift and Broken Tiles in a High-Wind Zone
A coastal house has a 5:12 concrete tile roof at a 30 ft mean roof height. The tiles are 24 in. by 16 in. and were installed with one nail per tile through the headlap, without battens. The underlayment is a single layer of 30-lb felt. Hip and ridge tiles are set in mortar. After a tropical storm with estimated 100 mph gusts, about 40 field tiles are cracked or displaced, mainly at the eave, ridge, and hip corners. The homeowner reports leaks at the hip and near the eave. The local code requires a wind-uplift design for the site, and the tile manufacturer lists a mechanical attachment pattern for this wind speed. The owner wants to replace only the broken tiles and re-mortar the hips.
1. Is replacing only the broken tiles and re-mortaring the hips an adequate repair? Explain the likely failure mode.
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It is not adequate. The failure pattern, concentrated at the eave, ridge, and hip corners, points to wind uplift rather than random breakage. One nail per tile through the headlap is a minimum attachment for low wind, not for a 100 mph gust in a coastal zone. Without battens, the tile system relies entirely on the nail and the tile bearing; uplift can crack tiles at the nail hole and lift them. Mortar at hips and ridges is brittle and cracks under movement, so re-mortaring alone will not restore wind resistance.
Replacing only visible broken tiles leaves adjacent tiles with the same inadequate attachment. The repair must evaluate the entire roof area for loose or cracked tiles, verify the underlayment, and upgrade attachment to the manufacturer's pattern for the design wind speed. The hip and ridge should be mechanically fastened in addition to mortar or set with approved adhesive. The eave and perimeter need enhanced attachment because those zones see the highest uplift.
2. What inspection and repair sequence would you specify, including underlayment and attachment?
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Inspect the roof systematically: sounded and walk the field to find loose tiles, check for cracked tiles and broken corners, examine the eave and ridge, and probe the underlayment at the leak locations. Remove the damaged tiles and hip/ridge tiles in the affected areas. Inspect the felt for tears and deterioration; because it is a single layer of 30-lb felt, any breached area should be repaired or the underlayment replaced in that area with a compatible underlayment.
Reinstall tiles using the manufacturer's high-wind attachment pattern, with fasteners placed in the correct location and not overdriven. Use battens or approved tile clips if the manufacturer requires them for the design pressure. Mechanically fasten hip and ridge tiles and set them in approved mortar or adhesive, maintaining weep paths. Replace all cracked tiles, not only displaced ones. At the eave, verify the drip edge and closure. After repair, have the attachment verified by a qualified inspector and document the fastener pattern for the code official.
3. How should the owner evaluate whether the existing underlayment and tile attachment meet the code wind requirement?
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The owner should obtain the design wind speed and exposure category from the code official, then compare the installed system with the manufacturer's published uplift-resistance assembly for that speed. The key variables are tile weight and profile, fastener type and penetration, attachment pattern, and whether battens or clips are required. One nail per tile with no battens is unlikely to match a high-wind assembly unless the manufacturer specifically allows it.
A qualified inspector should verify the fastener pattern and embedment, check that the tile is not nailed too high or too low, and confirm that the underlayment is appropriate for the tile system. If the assembly cannot be documented, the owner has two choices: upgrade the attachment to the manufacturer's high-wind pattern or have an engineer evaluate the existing system. Because the roof already failed at the perimeter, the conservative approach is to upgrade the eave, ridge, and hip zones first, then evaluate the field. The repair should be permitted and inspected if required.