You’re not alone—keeping a roof clean down here is a losing battle most of the time. I’ve had the same luck with zinc strips; they just make weird lines and don’t really stop the algae. For copper, I tried a short run over my porch roof and honestly didn’t notice much difference after one season, maybe because of our rain patterns or just not enough copper up there. Trimming back the limbs helped more than anything. Maintenance really is the name of the game, even if it’s a pain. At least you’re staying ahead of it—beats dealing with a mini forest up there again.
Trimming back the limbs made the biggest difference for us too. I used to get those black streaks every spring, no matter what I tried—zinc strips, that spray from the hardware store, you name it. Like you said, “
.” I noticed the same thing. The only time I saw a real improvement was after we took out a couple of big branches that shaded the roof all day.they just make weird lines and don’t really stop the algae
I’m not convinced copper is worth the price either, unless you’re doing a long run along the ridge. Even then, with our humidity and all the pollen, it’s still a constant battle. I’ve started hitting the trouble spots with a pump sprayer and some diluted bleach once a year—cheap and does the trick for a while, just gotta be careful with runoff. Not perfect, but better than nothing.
Honestly, I think it’s just about keeping up with it and not letting it get out of hand. Like you said, beats having to scrape off a layer of moss every fall...
- Agree on limb trimming—it’s the first thing I recommend, especially with north-facing slopes. Shade plus moisture is just asking for algae.
- Zinc and copper strips can help, but like you said, they’re not a cure-all. I see a lot of folks disappointed after spending money on those. Unless you’ve got a really steep pitch and good runoff, they mostly just leave stripes.
- Bleach mix works, but be careful—too strong and it’ll eat at your gutter hardware or drip into landscaping. I usually suggest 1:3 bleach to water, and only on overcast days to avoid quick evaporation.
- Maintenance is key. Once a year seems about right unless you’re in heavy tree cover.
- One thing I’ve seen make a difference: switching to algae-resistant shingles when it’s time to re-roof. Atlas has some with Scotchgard that seem to hold up better, at least in my area (humid summers, lots of pollen). Not perfect, but less streaking over time.
Curious if anyone’s tried those newer roof wash products—not the big box stuff, but the pro-grade ones? Wondering if they’re worth the extra cost or just marketing...
I’m with you on limb trimming—makes a bigger difference than most folks realize, especially if you’re in a spot that stays damp. I’ve seen those zinc and copper strips work okay, but like you said, they’re not magic. Sometimes they just leave weird streaks and don’t really stop the algae from coming back.
On the pro-grade roof wash stuff, I’ve tried a couple brands (Roof-A-Cide and Spray & Forget Pro). They’re definitely pricier, but I noticed less regrowth for about a year compared to bleach. Still, you gotta be careful with runoff—some of those chemicals are rough on plants. If you’re already doing annual maintenance, I’m not sure it’s worth the extra cost unless you’ve got a real stubborn case.
That lines up with my experience—those pro washes do seem to slow things down, but I always worry about what’s dripping onto my shrubs. Have you found any way to protect plants when you use that stuff? I’m with you on the cost, too. I just stick to bleach and a brush most years, but maybe I’m missing out on something longer-lasting...
