New Orleans is hard on roofs. Between the year-round humidity, summer storms that blow through with almost no warning, and temperatures that push materials to their limits, an asphalt roof here lasts 10 to 15 years — not the 20-year lifespan you’ll see on the manufacturer’s packaging. That number assumes a mild climate. We don’t have one. If your roof is getting up in age or you’ve been through a few hurricane seasons without an inspection, here are the signs that tell you it’s time to act.
Those dark streaks running down your roof aren’t dirt — they’re Gloeocapsa magma, a type of blue-green algae that feeds on the limestone filler in asphalt shingles. It thrives in warm, humid conditions, which means New Orleans roofs are basically an all-you-can-eat buffet. With humidity averaging above 75% year-round, algae takes hold fast and spreads across the entire roof surface if left alone.
Algae itself won’t destroy your roof overnight, but it holds moisture against the shingle surface. Over time, that accelerates granule loss and shortens the shingle’s useful life. If your roof has gone from gray to streaky black in the last couple of years, that’s worth a closer look.
Shingles curl in two ways: the edges lift up (cupping) or the middle pushes up while the edges stay flat (fishmouthing). Both are signs that the shingle is losing its flexibility and its ability to shed water properly.
In New Orleans, thermal cycling drives this faster than in cooler climates. Materials expand in the daytime heat and humidity, then contract overnight as temperatures drop. That constant push-and-pull loosens nails and cracks the sealant strips that hold shingle tabs down. Once the seal breaks, wind gets underneath, and things go downhill from there.
Finding a shingle or two in the yard after a thunderstorm might seem minor, but it’s a sign your roof’s wind resistance is failing. Properly installed architectural shingles are rated up t
By Big Easy Roofing 
Apr 19, 2023