Interesting you mention the zinc strips—I've seen mixed results with those, especially if the roof pitch is low or the rain doesn't wash down evenly. Did you notice any difference after a heavy storm, or was it pretty much the same? Also, curious if you ever tried any of those spray-on treatments folks talk about. I always wonder if they're worth the hassle or just a temporary fix.
I get where you’re coming from with zinc strips—honestly, on a low-pitch roof, I’ve seen them barely make a dent unless you get a real downpour. Sometimes the runoff just doesn’t spread out enough to do the job. As for those spray-on treatments, I tried one about two years back after a stretch of heavy rain left my north-facing shingles looking green. It knocked back the algae for maybe a season, but by the next spring it was creeping back. In my experience, nothing beats a good manual cleaning and keeping trees trimmed back for airflow. The quick fixes always seem to be just that—quick, but not lasting.
In my experience, nothing beats a good manual cleaning and keeping trees trimmed back for airflow. The quick fixes always seem to be just that—quick, but not lasting.
That’s been my take too, especially with north-facing slopes. I’ve seen folks get their hopes up with zinc strips or copper wire, but unless you’ve got a steep pitch and regular rain, it’s like expecting a garden hose to clean your whole driveway. Ever tried those “algae-resistant” shingles? Atlas markets theirs pretty hard, but I’ve been back on jobs five years later and still spotted the green stuff creeping in.
Manual cleaning is a pain though—climbing up there every spring isn’t everyone’s idea of a good time. I had one customer who swore by using a leaf blower every couple weeks to keep debris off, and honestly, his roof stayed cleaner than most. Not sure if it was the airflow or just luck.
Curious if anyone’s had luck with those longer-lasting spray treatments? I know you said yours only lasted a season, but I keep seeing new brands pop up claiming “multi-year protection.” Is that just marketing fluff, or has someone actually seen them work for more than a year or two?
Also—does anyone bother with gutter guards for this? I’ve noticed when gutters are clogged and water backs up, the algae seems worse right along the eaves. Maybe it’s just coincidence, but it makes me wonder if keeping water moving helps at all.
And yeah, tree trimming is huge. Had one job where we took out two big maples overhanging the roof and suddenly the moss/algae problem basically vanished. Makes me think shade is half the battle... or maybe more like 80% of it.
Anyone ever try those “roof washing” companies that promise not to damage shingles? I’m always skeptical about pressure washing asphalt, but maybe there’s a gentle way to do it without blowing off granules.
I’ve seen those “multi-year” spray treatments in action, and honestly, most of the time it’s wishful thinking. Maybe you get a year, tops, before the algae starts showing up again—especially on the shady side. Gutter guards do help a bit, mostly by keeping leaves out and letting water flow, but I haven’t noticed a huge difference with algae itself. As for those roof washing companies, I’ve watched them work—if they’re using low pressure and lots of rinse water, it seems pretty gentle. Still makes me nervous seeing someone up there with any kind of power washer, though... one bad move and your shingles are toast.
I get the hesitation with power washers—seen too many roofs get trashed by someone getting a little too aggressive. But have you ever tried installing zinc or copper strips near the ridge? I’ve seen those make a real difference, especially on north-facing slopes where algae loves to hang out. The rain washes tiny amounts of metal down the shingles and it seems to keep the green stuff at bay for a couple years, at least in my area. Curious if anyone’s had luck with that approach, or if it’s just a regional thing...