Why Are My Roof Shingles Buckling? Causes & Fixes

Shingle buckling shows up as ridges or waves running across your roof surface, making the shingles look wavy or distorted rather than lying flat. Unlike curling shingles, which is a problem with the shingle material itself, buckling is almost always caused by something going wrong beneath the shingles — moisture in the roof deck, wrinkled underlayment, or boards that were not spaced properly during installation.

That distinction matters because it changes the repair approach entirely. Replacing the visible shingles without fixing the underlying cause is a waste of money — the new shingles will buckle the same way. Effective repair means identifying and correcting the root cause first, then addressing the shingles on top.

In the Myrtle Beach area, buckling is more common than in drier climates because of our persistent humidity. Moisture finds its way into roof decking through inadequate ventilation, vapor drive, and the daily humidity cycling that comes with coastal living. Repairs typically run $200 to $2,000 depending on the cause and scope, though extensive deck damage can push costs higher.

What Shingle Buckling Looks Like

Buckling is easy to spot once you know what you are looking for. Instead of lying smooth and flat, affected shingles form visible ridges or waves that typically run vertically (from eave to ridge). The distortion usually spans multiple shingles in a line because the problem underneath — a swollen deck board edge, a wrinkle in the underlayment, or a gap between boards — runs in a continuous line beneath several shingle courses.

From ground level, buckling looks like the roof surface is rippled or has bumps. In the right light (early morning or late afternoon when shadows are long), the raised ridges become especially visible. Buckling can appear on new roofs within weeks of installation or develop gradually on older roofs as moisture accumulates in the decking.

Buckling is sometimes confused with the normal factory crease line that runs across the center of each shingle. The difference is that factory creases follow individual shingle lines uniformly, while buckling creates irregular ridges that cross shingle boundaries and are noticeably raised above the surrounding surface.

Top 5 Causes of Shingle Buckling

1. Moisture in the Roof Decking

This is the most common cause of buckling in coastal South Carolina. Plywood and OSB (oriented strand board) roof decking absorb moisture from humid attic air, from condensation, or from small leaks that have not yet shown up inside the home. When the decking absorbs moisture, it swells. Since the sheets are fastened tightly to the rafters, the swelling pushes upward at the edges and joints, creating the ridges that show through the shingles above.

In Myrtle Beach, where humidity regularly exceeds 80% in summer months, even properly vented attics can see enough moisture cycling to cause decking edges to swell slightly. Attics with inadequate ventilation, bathroom fans venting into the attic space, or missing vapor barriers are especially vulnerable. OSB is more susceptible to moisture-induced swelling than plywood, and many homes built in the 1990s through 2000s used OSB decking as a cost-saving measure.

2. Improper Shingle Installation

Shingles nailed too tightly (overdriven fasteners) cannot accommodate normal thermal expansion and contraction. As the shingle material heats up and expands during the day, it has nowhere to go and buckles upward. Similarly, shingles that are not properly offset (staggered) from course to course can create alignment issues that manifest as buckling. Poor nailing patterns — nails placed too high on the shingle, at angles, or in inconsistent positions — also contribute to buckling by creating uneven tension across the shingle surface.

3. Poor Attic Ventilation

Ventilation connects directly to the moisture problem. A properly ventilated attic allows hot, humid air to exhaust through ridge vents while drawing drier air in through soffit vents. Without this airflow, moisture-laden air sits against the underside of the roof deck, condensing on cooler surfaces and gradually saturating the wood. The result is swollen decking that pushes shingles upward. Ventilation-related buckling often appears first in the center of the roof (farthest from eave-to-ridge airflow) and during the hottest months when the temperature differential drives the most condensation.

4. Wrinkled or Misaligned Felt Paper (Underlayment)

Roofing underlayment (felt paper or synthetic) is installed over the decking before the shingles go on. If the underlayment is wrinkled during installation — from being rolled out in hot sun, walked on before it relaxes, or not pulled taut — those wrinkles telegraph directly through the shingles above as visible ridges. This type of buckling is purely an installation problem. It usually appears immediately after a new roof is installed and does not worsen over time because the underlayment wrinkle is a fixed-position issue. The fix requires stripping the shingles in the affected area, smoothing or replacing the underlayment, and reinstalling the shingles.

5. Thermal Expansion of Deck Boards

Roof decking sheets need a small gap (typically 1/8 inch) between them to allow for thermal expansion. When decking is installed tight with no gap — either due to installer error or because the lumber was very dry at installation time and later absorbed ambient moisture — the expanding sheets push against each other and buckle upward at the joint. This creates a straight-line ridge that follows the decking seam beneath the shingles. The problem is most visible during the hottest months when expansion is greatest and may partially recede in cooler weather, though it never fully flattens if the spacing is inadequate.

Buckling vs. Curling: When Each One Matters

Both buckling and curling make your roof look wrong and create vulnerability to leaks and wind damage. But they are different problems requiring different solutions.

The most important thing to understand is that buckling repair must address the cause underneath the shingles. A contractor who proposes to simply replace the buckled shingles without investigating the decking or underlayment beneath them is not solving the problem. New shingles installed over swollen decking or wrinkled underlayment will buckle the same way. For a detailed guide on curling specifically, see our complete curling shingles guide.

Repair Options and Costs

Buckling repair costs depend almost entirely on what is causing the problem. Here is what Myrtle Beach homeowners typically pay for each type of repair in 2026.

Underlayment Wrinkle Correction: $200 - $600

If wrinkled felt paper is the cause, the roofer strips the shingles in the affected area, smooths or replaces the underlayment section, and reinstalls the shingles. This is the simplest and cheapest buckling repair. The labor is straightforward and the material cost is minimal. If the shingles are in good condition (relatively new), they can often be reused, keeping costs lower.

Deck Board Spacing Repair: $400 - $1,200

When decking was installed without adequate expansion gaps, the repair involves removing shingles and underlayment in the affected area, trimming the deck board edges to create proper spacing (1/8 inch between sheets), reinstalling underlayment, and reshinging. If the boards have buckled severely or delaminated from the expansion pressure, some sheets may need full replacement rather than just trimming.

Moisture Damage Repair: $800 - $2,000+

Moisture-related buckling is the most expensive to fix because it involves replacing waterlogged or delaminated decking sections, correcting the ventilation or moisture source that caused the problem, and then reshinging the area. The decking replacement itself ($40-$80 per sheet of plywood or OSB installed) adds up quickly when multiple sheets are affected. Adding ridge vents, soffit vents, or correcting bathroom fan ducting adds $300 to $1,500 to the total but is essential to prevent recurrence.

For any roof repair in the Myrtle Beach area, always get a written estimate that specifies what the roofer will do underneath the shingles, not just what the visible repair looks like from outside. The underlying fix is where the real value is.

When Buckling Means You Need a New Roof

Targeted repair works well when buckling is limited to a specific area with an identifiable cause. But there are situations where full roof replacement is the smarter investment.

• Widespread deck damage. If moisture has compromised decking across large sections of the roof, the cost of stripping shingles, replacing decking, and reshinging area by area approaches or exceeds the cost of a full replacement done all at once.
• Buckling combined with other damage. When buckling appears alongside curling, granule loss, cracked shingles, or flashing failures, the roof is failing on multiple fronts. Fixing one problem while others worsen is not cost-effective.
• The roof is older than 20 years. Decking moisture problems on an aging roof suggest the whole system is reaching end of life. Replacement allows you to upgrade decking, ventilation, underlayment, and shingles all at once.
• Structural concerns. If buckling is severe enough that you can see visible sagging or feel soft spots when walking on the roof, the decking may be compromised beyond spot repair. A licensed roofing contractor should inspect the full deck structure before proceeding.

Why Myrtle Beach Homes Are More Prone to Buckling

The coastal South Carolina climate creates a uniquely challenging environment for roof decking that directly contributes to higher rates of shingle buckling compared to inland areas.

Persistent Humidity

Myrtle Beach averages 73% relative humidity year round. In summer, it regularly exceeds 80%. That moisture-saturated air infiltrates attic spaces and is absorbed by roof decking, especially OSB, which swells more readily than plywood. Even homes with adequate ventilation experience moisture cycling that stresses decking over time. Homes with inadequate ventilation, sealed soffits, or attic-vented bathroom fans face accelerated decking deterioration that leads to buckling years earlier than expected.

Thermal Cycling

The daily temperature swing from cool mornings to hot afternoons drives a constant expansion-contraction cycle in roof decking. Summer roof surface temperatures in the Myrtle Beach area can reach 150-170°F during the afternoon and drop to 70-80°F overnight. That 80-100 degree daily swing pushes deck boards against each other during peak heat and contracts them overnight. Over years, this cycling loosens fasteners, widens board joints unevenly, and creates the conditions for moisture intrusion and buckling. Homes with dark-colored shingles experience even more extreme thermal cycling.

Frequently Asked Questions About Shingle Buckling

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