Roof Buckling: Causes, Solutions and Prevention

A structurally sound Houston roof will protect your house and possessions from rainwater or melting snow that has accumulated during the winter months. A roof should look smooth if it is in good condition. Ripples or waves on the roof surface are a sure sign that the shingles or decking has probably buckled. Roofs buckle because either the roofing underlayment has wrinkled or the wood deck itself has shifted for some reason. Occasionally, the buckling is caused by poor workmanship, wrong materials or possibly by a problem with the structure itself. A Houston roofing contractor can assess the severity of the buckling and take care of the problem for you.

Causes of Buckling

Several factors can cause buckled shingles, especially if you had a Houston roof replacement during the hot, humid months of a Houston summer. When an old roof is removed, moisture is absorbed by the wooden deck. This could make the deck shift due to the increase in moisture content.

Nowadays, homes have more insulation and tighter building tolerances, so they might not have adequate ventilation. That results in moisture becoming trapped in the roof system, which causes the felt underlayment, commonly called tar paper or felt, to absorb the moisture and wrinkle. Your Houston roofing company should check the recommendations from each manufacturer to make sure that additional ventilation is added when necessary. Buckling can also occur if the tar paper was stretched and applied to your roof improperly.

Expansion and contraction in the decking happens if spacers were not used. Spacers are placed between the decking boards that absorb any expansion from excessive heat. The decking can also buckle if it is not fastened to the framing correctly or if water leaks beneath the roof’s shingles. The decking will rot from continuous exposure to water, which would seriously damage your home.

Sometimes, new shingles are applied directly on top of old, uneven shingles. A “roof-over” or “re-roof” is not recommended because it will certainly lead to buckling.

Buckling can occur if the wrong type of nails were used to connect the sheathing to the rafters. The nails slip out of the sheathing and create small visible bumps on the surface of your roof. A broken, sagging rafter will also cause a dip in the roof’s surface.

Solutions to Roof Buckling

  • By removing the affected shingles, the wrinkled tar paper can be repaired by cutting and reattaching it so that it is flat. Then, existing or new shingles can be replaced.
  • Excess moisture must be allowed to exit the roofing system. After it dries, the roof should be flat again. As long as it stays dry, the buckling will not come back.
  • Properly vent the attic. For every 150 square feet of attic floor space, there should be at least 1 square foot of free vent area. If your vapor barrier has a perm rating of 1 or less, you can reduce the ventilation area to 1 square foot per 300 square feet of attic floor space as long as you allow 50 percent of the ventilation at the eaves and 50 percent at the top of the roof.

How to Prevent Roof Buckling

  • Only use wood decking materials that are at moisture equilibrium with the local environment. They should also be approved by the roofing manufacturer.
  • Keep all decking materials dry before and after installation.
  • Use an asphalt-saturated felt shingle underlayment to cover the decking materials before applying the shingles.
  • Follow the manufacturer’s recommendations for ventilation requirements. You might have to add exhaust fans to adequately ventilate the attic space and remove built-up moisture.
  • Install the shingles according to the manufacturer’s guidelines.
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