If you’ve got Atlas shingles and live somewhere humid (I’m in Georgia, so yeah, algae is basically a neighbor), here’s something that’s worked for me: Scotchgard. I know, sounds like something for your couch, but the version for roofing actually helps keep those ugly black streaks away. I had my roof done two years ago with the Scotchgard protection, and honestly, it still looks way cleaner than my neighbor’s—he skipped it and now his roof looks like a science experiment.
It wasn’t a huge upcharge either, which surprised me. I just made sure to ask the installer for the Scotchgard option when picking out my shingles. Not saying it’s magic or anything, but it does seem to slow down the grossness.
Anyone else tried this or found other ways to keep algae at bay? I’ve heard copper strips work too, but haven’t tested that myself. Curious what’s working for folks in other climates.
- Scotchgard is definitely getting more popular, but I’ve seen mixed results across different properties. Some roofs look great, others still get streaks after a couple years—maybe installer technique matters?
- For multi-unit buildings, we’ve had better luck with copper strips at the ridge. They’re not the prettiest, but rainwater carries the copper down and it really does slow algae growth. The upfront cost is higher than a spray-on treatment, but you don’t have to reapply anything later.
- One thing to watch: if you’re in an area with a lot of tree cover, even Scotchgard or copper won’t stop everything. Shade + humidity = algae magnet. We ended up trimming back branches and that helped more than any product.
- Maintenance-wise, pressure washing is tempting but can damage shingles. We tried a soft wash (low pressure + cleaning solution) on one building and it worked without voiding the warranty—worth looking into if you’re dealing with older roofs.
- I’d be careful about relying only on chemical treatments long-term. Some tenants are sensitive to runoff, especially if you have gardens or pets around.
- For what it’s worth, our insurance adjuster mentioned that visible algae doesn’t affect coverage or claims, but it does make the place look less cared for... which can matter for curb appeal.
Not knocking Scotchgard—if it’s working for you, awesome—but I wouldn’t call it a set-it-and-forget-it fix everywhere. Sometimes a combo of things works best, especially in these muggy southern climates.
Sometimes a combo of things works best, especially in these muggy southern climates.
That’s been my experience too. I’ve seen folks swear by Scotchgard, but I’m not convinced it’s a universal fix—especially under big oaks or in those deep-shade spots. Installer technique definitely matters, but even with a good application, you’re still fighting nature if the roof never dries out.
Copper strips are solid for long-term control, though yeah, not winning any beauty contests. The upfront cost stings, but not having to reapply anything every year is a plus in my book. I’ve even seen folks use zinc strips as a cheaper alternative, though they don’t last as long.
Honestly, nothing beats just letting the sun hit the shingles. We trimmed back a ton of branches last year and suddenly our north side stopped looking like a science experiment. Soft washing is great as long as you’re careful about runoff—those chemicals can do a number on veggie gardens if you’re not watching where the water goes.
Bottom line, there’s no magic bullet. Just gotta use a mix of tactics and keep an eye on things... especially once the humidity ramps up.
Honestly, nothing beats just letting the sun hit the shingles.
I hear you on the sunlight, but I’ve seen plenty of roofs still go green even after a good trim—especially if you get those endless afternoon thunderstorms. Ever try using those algae-resistant granule shingles? They claim to help, but I’m not totally sold... seems like after a few years, nature finds a way.
They claim to help, but I’m not totally sold... seems like after a few years, nature finds a way.
That’s been my experience too. I put on the algae-resistant shingles about six years back, and honestly, they looked great for maybe three summers. After that, the streaks started creeping in again—especially on the north side. I’ve tried zinc strips near the ridge, and those seem to slow things down a bit, but nothing’s foolproof. Maybe it’s just the Florida humidity, but I’m starting to think regular cleaning is just part of the deal.