How to Fix Curling or Buckling Shingles
Curling and buckling shingles are more than a cosmetic problem—they create gaps where wind-driven rain can penetrate the underlayment and reach the roof deck. Understanding why your shingles are deforming is essential to choosing the right fix, because gluing down a symptom of poor ventilation without addressing the root cause means you'll be back on the roof within a year.
Quick Summary
Time Required
30–60 minutes per area
Difficulty
Moderate
Cost
$10–$50 (DIY materials)
Understanding Curling, Cupping, and Buckling
Shingle deformation takes three distinct forms, and each one tells you something different about what is happening to your roof. Correctly identifying the pattern determines whether a simple repair will work or whether you need to address a systemic issue first.
Cupping (edges curl upward)
The edges of the shingle tab turn upward while the center remains flat, creating a concave shape. This is most commonly caused by moisture absorption from below—often due to inadequate attic ventilation—or by natural aging as the asphalt dries out and contracts from the exposed top surface faster than the protected bottom surface.
Clawing (center rises, edges stay flat)
The center of the shingle tab pushes upward while the edges remain adhered to the roof. Clawing is typically caused by excessive heat from poor ventilation, age-related shrinkage of the fiberglass mat, or a manufacturing defect. Clawed shingles are highly vulnerable to wind uplift.
Buckling (visible wave or ridge)
A distinct wave or ridge runs across multiple shingles, usually in a vertical line. Buckling is almost always caused by movement in the deck sheathing beneath—plywood that was not properly spaced for expansion, wrinkled underlayment, or a second layer of shingles installed over an uneven first layer.
Diagnosing the Root Cause
Before you repair the shingles themselves, check these common underlying issues. Fixing the surface without addressing the cause guarantees the problem will return.
- Attic temperature check: On a sunny afternoon, go into your attic. If it feels significantly hotter than the outside air, your ventilation is likely inadequate. Attic temperatures should track within 10–15 degrees of the outside temperature when ventilation is working properly.
- Moisture assessment: Look for condensation on the underside of the roof deck, damp insulation, or water stains on rafters. Trapped moisture accelerates shingle deterioration from below and is the primary driver of cupping.
- Shingle age: If your shingles are within five years of their rated lifespan (typically 20–30 years for three-tab, 30–50 for architectural), widespread curling is a natural end-of-life symptom. Individual repairs make less economic sense at this stage.
- Installation history: Check whether shingles were installed over a previous layer. Double-layered roofs are more prone to buckling because the uneven surface beneath prevents the new layer from lying flat.
Repairing Curled Shingles with Roofing Cement
For shingles that are still pliable and have retained most of their granules, a roofing cement repair can extend their life by several years. This technique works best for cupped edges and mildly clawed shingles. Work on a warm day when shingles are most flexible—ideally between 50 and 80 degrees Fahrenheit.
- Prepare the surface: Gently lift the curled edge and brush away any loose granules, dirt, or debris from both the underside of the curled shingle and the surface beneath it. Clean surfaces bond much better than dirty ones.
- Apply roofing cement: Using a caulk gun, apply a generous bead of roofing cement (also called roof sealant or plastic cement) to the underside of the curled area. Cover the full area that needs to be re-adhered—do not just spot-apply.
- Press and weight: Firmly press the shingle flat into the cement. Place a brick, sandbag, or other weight on top of the repaired area and leave it for at least 24 hours. This sustained pressure ensures a strong bond as the cement cures.
- Remove weight and inspect: After 24 hours, remove the weight and check that the shingle is lying flat. Press on the edges to confirm they are securely bonded. Apply additional cement to any spots that did not adhere fully.
When Replacement Is the Better Option
Not every curling shingle can be saved. Attempting to flatten a brittle shingle will crack it, creating a worse problem than the original curl. Here are the signs that replacement is the right call:
Shingle cracks when flexed
If the shingle snaps or develops new cracks when you try to press it flat, the asphalt has dried out beyond repair. Replace it with a new shingle using the technique from the previous step in this checklist.
Severe granule loss on the curled area
If the underside of the curl or the exposed area shows bare asphalt with little granule coverage, the shingle has lost its UV and weather protection. Gluing it flat will stop wind damage but will not restore its waterproofing ability.
More than a third of visible shingles are affected
When curling is widespread rather than isolated, it signals a systemic issue—usually end-of-life aging or a chronic ventilation problem. Patching dozens of individual shingles is neither cost-effective nor a long-term solution. Consult a roofing contractor about full replacement.
Pro Tips
- •Time repairs for warm afternoons: Shingles are most pliable between 60–80°F. Attempting repairs in the early morning cold risks cracking the shingle when you press it flat.
- •Use a heat gun carefully on stubborn curls: A heat gun on low setting can soften a stiff shingle enough to flatten it without cracking. Keep the gun moving to avoid melting the asphalt or damaging the granule coating. Never use an open flame.
- •Fix ventilation before fixing shingles: If your attic is poorly ventilated, adding soffit vents or a ridge vent is a higher priority than gluing down individual shingles. Proper airflow prevents new curling from developing on both repaired and unaffected shingles.
- •Document widespread curling for insurance: If curling appeared after a major weather event, photograph it extensively before making repairs. Some homeowner's insurance policies cover wind or hail damage to shingles, but they require documentation of the damage before any repair work begins.
Frequently Asked Questions
What causes shingles to curl or buckle?
The most common causes are age-related drying of the asphalt, inadequate attic ventilation trapping heat and moisture, improper installation over wrinkled underlayment, a second layer of shingles installed over an uneven first layer, and moisture absorption in the shingle mat. Poor ventilation is the most frequent culprit in homes less than 15 years old.
Can curling shingles be repaired or do they need to be replaced?
Mildly curled shingles that are still flexible can often be repaired by gluing them flat with roofing cement. However, if the shingle is brittle, cracked, or has lost significant granules, it should be replaced. If curling is widespread across the roof, it usually indicates the shingles are near the end of their useful life and a full re-roofing is the most practical solution.
Will fixing attic ventilation stop my shingles from curling?
Improving attic ventilation can slow or stop further curling by reducing the trapped heat and moisture that accelerate shingle deterioration. However, it will not reverse damage that has already occurred. Shingles that have already curled will need to be repaired or replaced individually, but correcting the ventilation issue will help prevent the same problem from recurring with new shingles.
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