You pull into your driveway, look up at your house, and notice something unsettling. Your roof, which used to look flat and uniform, is starting to look textured—and not in a good way. The edges of the shingles are turning up, or the centers are humped.

Curling and cracking shingles are the roofing equivalent of wrinkles; they are a sign of aging, stress, and environmental wear. But unlike wrinkles, you can’t just use a good moisturizer to fix them. Understanding why this happens is the first step in deciding whether you need a repair or a full replacement.

The Anatomy of Curling

First, let’s get the terminology right. There are two main ways shingles distort:

1. Cupping: This happens when the edges of the shingle turn upward, creating a cup-like shape. This exposes the edges to wind and rain.
2. Clawing: This is the opposite. The middle of the shingle bubbles up while the edges stay flat or curl under.

Both are bad news. They mean the shingle is no longer lying flat, which compromises the water-shedding ability of the roof.

Cause #1: Poor Attic Ventilation

This is, without a doubt, the most common culprit. Your attic needs to breathe. It requires intake vents (usually at the soffits) and exhaust vents (at the ridge or roof face) to cycle air through.

If your attic is poorly ventilated, heat and moisture get trapped. In the Texas summer, attic temperatures can soar to 150°F or higher. This intense heat bakes the shingles from the bottom up. Over time, the asphalt dries out and shrinks, causing the edges to curl. If you are unsure about your ventilation, checking it is a key part of our roof repair services in Katy, TX.

Cause #2: Improper Installation

Sometimes, the problem starts the day the roof is nailed down.

☑ High Nailing: If the installer places the nails too high on the shingle, the bottom edge isn’t secure. Over time, wind and thermal cycles will cause it to lift and curl.

☑ Misaligned Tar Lines: Shingles have a strip of adhesive tar that seals them to the row below. If this doesn’t line up correctly, the bond fails, and the shingle is free to move and warp.

Cause #3: The Phenomenon of “Thermal Shock”

roofs go through extreme temperature cycles. In the morning, they might be cool. By 2 p.m., they are scorching hot. Then a summer thunderstorm rolls in, dumping cold rain on the hot asphalt. This rapid cooling causes the material to contract quickly.

Over years of expanding and contracting, the structural integrity of the asphalt mix breaks down. The shingles lose their flexibility and begin to crack or curl under the stress. This is one reason understanding the average lifespan of an asphalt shingle roof is important; eventually, physics just wins.

Cause #4: Layering (Reroofing over Old Shingles)

To save money, some homeowners opt to install a new layer of shingles directly over the old one. While legal in some jurisdictions, it is rarely a good idea for longevity. The second layer doesn’t seal as well as the first, and it traps even more heat. The added heat stress almost guarantees the new top layer will curl and crack faster than if you had done a complete tear-off.

Cause #5: Defective Materials

While less common today, there have been historical batches of “organic” shingles (made with a cellulose mat rather than fiberglass) that were notorious for absorbing moisture and curling prematurely. If your roof was installed roughly 15-20 years ago, you might be a victim of inferior manufacturing standards from that era.

Can You Fix Curled Shingles?

This is the million-dollar question.

• The hard truth: Once a shingle has curled, it cannot be flattened back out. The material has physically deformed.
• The solution: If the curling is limited to a small area (perhaps near a vent where heat escapes), you can replace just those specific shingles.
• The reality: If the curling is widespread across the roof, it is a systemic failure. The shingles are brittle and will likely break if you try to manipulate them.

If you see widespread curling, your roof has lost its ability to waterproof your home effectively. It is time to look into a new roof installation in Houston, TX before the water starts coming in.