Why are my shingles curling and cracking?

Heat, UV, and age: the Gardena combination

Asphalt shingles age fastest where they are hottest and sunniest, and Gardena offers both for months at a time. Summer sun breaks down the asphalt binder, granules loosen and wash into gutters, and the shingle mat underneath becomes brittle. Once a shingle is brittle, normal thermal movement, the daily expansion and contraction of the roof, is enough to crack it instead of flexing with it.

Age multiplies the effect. Gardena's median year built is 1964, and many of the city's 1950s and 1960s houses have had one or two shingle roofs already. A shingle roof near the end of its service life does not fail all at once; it curls and cracks slope by slope, usually starting on the sunniest, south- and west-facing slopes.

Lifespans are discussed in general market terms only, and any number a contractor gives for your roof should be tied to its actual condition, not to a citywide average.

Cupping, clawing, and cracking: what each means

• Cupping. The edges of a shingle curl upward, forming a shallow cup. This is usually the top surface ageing and shrinking faster than the underside, and it is often worse on sun-exposed slopes.
• Clawing. The middle of the shingle lifts while the edges stay down, the reverse of cupping. Clawing often points to moisture or heat trapped from below, and it is a reason to check attic ventilation rather than just the shingle.
• Cracking. Splits through the shingle, sometimes in a pattern following the mat. Cracking means the shingle has lost flexibility, and cracked shingles no longer seal reliably against wind-driven rain.
• Granule loss. Bare patches, or heavy granule build-up in gutters and at downspout outlets, mean the protective surface is going. Granule loss on its own is ageing; granule loss plus curling is a roof nearing replacement.

Ventilation and installation factors

Attic ventilation is the second half of the heat story. When hot air cannot escape, the roof deck stays hotter for longer, and shingles bake from both sides. Poor ventilation does not create curling on its own, but it accelerates every other ageing mechanism, and it is one of the first things checked when curling appears well before a roof's expected life. See our roof ventilation page for how vents work as part of the roofing assembly.

Installation history matters too. Shingles laid over an old layer, or over decking that was already uneven, curl sooner because they cannot lie flat. Gardena sources note two-layer tear-offs over older stock as a real cost driver here, which is a reminder that what lies under the shingles affects how long the new layer lasts.

Repair or replace: an honest call

A handful of curled or cracked shingles on an otherwise sound roof is a shingle roofing repair: replace the damaged shingles, check the flashing and ventilation around them, and monitor the slope. Widespread curling across a whole slope, cracking combined with granule loss, or curling that has already let water in, points the other way. Patching a slope that is failing everywhere is money spent twice, and at that point roof replacement is the honest recommendation, not an upsell.

A roof inspection can document how much of the roof is affected before that call is made, and roof maintenance can slow further ageing on a roof that still has life in it. Homes in Hollypark and Moneta show both ends of this story: 1960s tract roofs ageing together, and older houses where one slope has been replaced and another has not, so the honest answer is always slope by slope, never a single rule for the whole city.

Get help with curling or cracking shingles in Gardena

If curling or cracking is widespread, or if shingles are already leaking, call Nexo Xpert Roofing at +1 (562) 600-4041 to discuss an inspection and an estimate. A few curled shingles can be a repair; a whole slope of them usually is not.