Keeping algae off Atlas shingles: My quick hack

- 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.

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.

Interesting to hear zinc strips helped a bit - I've always wondered if those are worth the hassle. I’m in the Carolinas, and it’s a similar story with algae, especially on the shaded side. I do like the idea of less chemicals (even if Scotchgard is “roof safe”), but honestly, I’m not sure if any of these treatments really last more than a few years. Has anyone tried just letting the roof “go natural” and seen if it stabilizes, or does it just keep getting worse? I keep seeing mossy roofs in Europe that look kind of cool, but maybe that’s just me...

Letting it “go natural” sounds kind of tempting, but I’m not sure it ever really stabilizes, at least around here. I’ve seen a few roofs where folks just left the algae and moss, and after a while, the shingles started curling or breaking down faster than usual. Maybe the climate in Europe is different, or maybe their roofs are built to handle it? I do wonder if there’s a sweet spot between constant cleaning and just letting nature take over... but so far, I haven’t seen it work out long-term on asphalt shingles.

I’ve wondered about that too, honestly. Around here (Pacific Northwest), if you let moss and algae go, it just seems to get worse every year. My uncle left his roof alone for a while, thinking it’d just “blend in,” but after a couple of winters, the shingles started cracking and lifting. Maybe it’s the constant damp? I’m curious if anyone’s actually had luck with those copper or zinc strips - do they really slow down the growth, or is it just a temporary fix?

I’m curious if anyone’s actually had luck with those copper or zinc strips - do they really slow down the growth, or is it just a temporary fix?

I’ve tried zinc strips on my own roof (asphalt, mid-slope, Seattle area) and honestly, they do help, but only right below where the strip sits. The runoff carries those ions down and inhibits growth, but areas farther down the roof still get algae. It’s not a total solution, more like a partial defense. The Pacific Northwest dampness just keeps feeding moss and algae... I think regular cleaning plus those strips is about as good as it gets unless you want to re-roof with something less prone to growth.

That lines up with what I’ve seen on a lot of inspections around here. Those strips definitely help, but only in the path of the runoff - anything outside that zone still gets the green fuzz, especially in shaded spots. I’ve noticed some folks try to run wider strips or even double up, but it doesn’t seem to make a huge difference once you get a few feet down the roof.

Curious if anyone’s tried those newer algae-resistant shingles? Some manufacturers claim they’ve got copper granules baked in, but I haven’t seen enough roofs with them to say if it’s worth the extra cost. Wondering if that’s a better long-term fix than just adding strips and scrubbing every year. Anyone had experience with those, especially in wetter climates?

I put those algae-resistant shingles on my shed a couple years back, mostly as an experiment since the north side always turned into a science project by midsummer. Honestly, they’ve held up better than I expected - still get a little bit of green in the deepest shade, but nothing like before. The upfront cost was higher, but I haven’t had to mess with strips or scrubbing since. If you’re in a really damp area, I’d say it’s worth considering, especially if you’re tired of climbing up there every spring.

Yeah, those algae-resistant shingles are a game changer for the north side. I’ve seen folks try copper strips, but honestly, they only do so much if you’ve got big trees nearby. Paying more upfront stings a bit, but not having to haul out the ladder every spring? Worth it in my book. Just wish they made gutters that resisted moss too…

That’s a good point about the copper strips - seems like they help a bit, but if you’ve got a lot of shade and debris, algae still sneaks in. I totally get the sting of paying more upfront, but not having to scrub the roof every year sounds like a win. Have you tried any gutter guards for the moss? I’ve heard mixed things, but maybe there’s something out there that actually works...

I’ve wondered the same thing about gutter guards - seems like every neighbor has a different story. My buddy swears by those foam inserts, but I tried them and just ended up with a soggy mess full of pine needles. Has anyone actually seen less moss on their roof after putting in guards, or is it just wishful thinking? I’m in the Pacific Northwest, so moss basically thinks my house is an Airbnb.

I hear you on the foam inserts - tried those a couple years back and they just turned into a pine needle sponge. I’m in Olympia, so moss is basically my roof’s permanent roommate. Here’s what I’ve figured out after a lot of trial and error (and a few questionable purchases):

First off, gutter guards themselves don’t really do much for moss on the shingles. They’re more about keeping the gutters clear, which helps with drainage and can reduce some moisture around the eaves, but moss is stubborn and loves our damp PNW weather. If anything, I noticed the guards made it easier to clean the gutters, but didn’t see any less green fuzz up top.

What actually helped me was installing zinc strips along the ridge line. It’s not magic, but when rain hits those strips, it releases a bit of zinc that runs down the roof and makes life harder for moss and algae. Here’s how I did it:

1. Picked up a roll of zinc strip from the hardware store (wasn’t too pricey).
2. Loosened the bottom edge of my ridge cap shingles - just enough to slide the strip underneath.
3. Nailed it down every couple feet with roofing nails (galvanized so they don’t rust).
4. Let nature do its thing.

It took a few months to notice a difference, but now there’s a visible line where the moss stops about halfway down each slope. Not perfect, but way better than before.

One thing: if your roof is super shaded or you’ve got overhanging branches, you’ll still get some moss no matter what. Trimming back trees helped me more than any product ever did.

If you’re dealing with Atlas shingles specifically, just double-check their warranty before messing around up there - some brands are picky about “modifications.” But honestly, between zinc strips and keeping debris off as much as possible (leaf blower works wonders), my roof looks way less like a chia pet these days.

Hope that helps someone else avoid buying another set of useless foam noodles...

Zinc strips are definitely the way to go in our climate. I tried the chemical moss killers a couple times, but they just made a mess and didn’t last through the winter. The zinc takes a while, but it’s low effort and you don’t have to keep reapplying anything. I’ve got Atlas Pinnacle Pristine shingles and checked with their warranty folks before putting up the strips - turns out as long as you’re not prying up whole shingles or using weird adhesives, they’re fine with it.

One thing I’d add: if you’ve got a really steep roof, be careful up there. I nearly slid off trying to nail in the last section... not my brightest moment. Also, if you’re dealing with a ton of tree debris, those leaf blowers are a lifesaver, but I’ve found a soft broom works better for stuck-on stuff after a dry spell.

I still get some moss on the north side where it never dries out, but it’s way less than before. Haven’t found anything that totally stops it, but between zinc and keeping things clear, it’s manageable.

Zinc strips have definitely saved me a ton of headaches, but I swear, every time I’m up there, I start questioning my life choices. Last fall, I tried to sweep off a patch of moss on the north side and ended up with half a pinecone in my shoe and a bruised ego. Anyone else notice the moss just laughs at you if you don’t keep up with the debris? I’ve got Atlas shingles too, and while the zinc helps, I still get those stubborn green patches in the shadiest spots. Ever tried copper strips instead? I heard they work faster, but I’m not sure if it’s worth swapping out what’s already up there.

I’ve got Atlas shingles too, and while the zinc helps, I still get those stubborn green patches in the shadiest spots.

Honestly, I’m starting to think moss is just part of the package deal with these shingles. I tried copper strips on my shed roof (way smaller, way less scary to climb), and yeah, it cleared up faster, but the price tag was a bit much for a full house. Plus, copper turns green too, right? At this point, I’m just hoping my roof doesn’t start growing mushrooms next...

Does anyone else wonder if the algae is just inevitable with these Atlas shingles, especially on the north side? I’ve tried both zinc and copper strips - copper definitely worked faster, but like you said, it’s not exactly cheap. Plus, the green patina just makes me laugh... am I fighting algae or just trading it for a different shade of green? Has anyone actually seen mushrooms up there, or is that just an urban legend?

I’ve actually climbed up on a few roofs with Atlas shingles in shaded spots, and yeah, algae seems almost unavoidable on the north side here in Georgia. Copper strips worked better for me too, but like you said, the cost adds up fast and that patina is kind of its own eyesore. Never seen mushrooms myself - just a lot of black streaks and some lichen. I guess if you had a ton of organic debris up there, mushrooms aren’t impossible, but I’d be surprised. Sometimes it feels like you’re just picking your battles with roof stains...