I’ve wondered the same thing about composite shingles. My neighbor got them a few years back and honestly, they still look pretty clean, but he’s got less tree cover than me. I’m not convinced they’re immune to moss—maybe just a little less grungy? As for synthetic underlayment, I used it on my shed roof and it definitely feels tougher than felt, but I doubt it helps with drying. Seems like if the sun can’t get in, nothing’s really drying out fast anyway...
I had composite shingles put on our place about six years ago, mostly because our old asphalt ones were getting chewed up by moss under the maples. They do seem to resist the green fuzz a bit longer, but after a few wet springs, I still had to get up there with a broom. The synthetic underlayment felt sturdier during install, but honestly, once the moss starts, it doesn’t really matter what’s underneath—it’s all about sunlight and airflow in my experience.
it doesn’t really matter what’s underneath—it’s all about sunlight and airflow in my experience.
That lines up with what I've seen, especially in shaded spots under big trees. Composite shingles do hold up a bit better against moss, but yeah, if the roof never dries out, nature finds a way. I switched to a lighter color composite a few years back and it helped a bit—less heat for moss to thrive on, maybe? Still, nothing beats trimming back branches for real airflow. Synthetic underlayment is great for leaks, but moss... that's a whole other battle.
I totally get what you’re saying about airflow—trimming back branches made a bigger difference for me than any shingle swap ever did. Still, I’ve always wondered if the lighter color really helps with moss, or if it’s just that it hides it better? I tried composite on my last place and yeah, less moss, but it still crept in where the sun never hit. Synthetic underlayment’s great for leaks, but like you said, moss is just relentless. At least you’re not alone in the fight...
Yeah, I’ve wondered about the color thing too. It seems like lighter shingles just don’t show the moss as much, but I’m not convinced they actually stop it from growing—especially on the north side where the sun barely hits. Where I live (Pacific Northwest), moss is just part of life. I switched over to a green roof setup on my shed last year—sedum and some native plants. No joke, zero moss issues so far, though obviously that’s a whole different thing from composite or asphalt.
I’ll agree with you about airflow though. Trimming back those overhanging branches made more of a difference than any shingle brand or color swap ever did for my main roof. The synthetic underlayment is solid for leaks, but if there’s no sun and lots of shade, moss will find a way... always does. I guess the only real “solution” would be moving somewhere with less rain, but that’s not happening for me anytime soon.
Funny enough, when I had asphalt shingles, they seemed to get ugly faster, but at least they were cheap to replace. Composite looks better longer, but still needs attention if you don’t want it taken over by green fuzz.
