- Not sure hardware cloth + flashing is enough long-term. Critters here (squirrels, mostly) chew right through sealant after a season or two.
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— That’s my main worry with sedum mats. Saw a neighbor’s porch roof sag after a wet spring.“that weight can stress older rafters if you’re not careful...”
- I stick with plain old shingles. Less “green,” but fewer surprises, especially on older houses.
- Drainage is always the weak spot, no matter the system. If you can’t see under the mat, you won’t know there’s a problem until it’s too late.
Seen this plenty—sedum mats look great at first, but I’ve inspected a few roofs where the extra weight (especially after a wet winter) led to sagging joists. Not worth the risk on anything built before the 80s, in my book. Shingles might not be “green,” but they’re predictable. And yeah, drainage always tells the real story... if you can’t see it, you won’t spot trouble until you’ve got rot.“that weight can stress older rafters if you’re not careful...”
Seen a lot of folks get seduced by those green roof pics online, but yeah—older rafters just aren’t built for that kind of load, especially once the mat soaks up a few weeks’ worth of rain. I’ve crawled through more than one attic where the joists looked like spaghetti noodles after a wet winter. Not exactly confidence-inspiring.
I get the appeal of going “eco,” but sometimes predictable is better, especially if you’re dealing with 60-year-old lumber that’s already seen a few decades of snow and ice. Shingles might not win any beauty contests, but at least you know what you’re getting into.
Drainage is the sneaky villain here. You can have the fanciest roof in the neighborhood, but if water’s pooling up there, it’ll find its way in eventually. Ever try explaining to someone that their “living roof” is now living in their living room? Not fun.
Curious if anyone’s tried retrofitting extra support under an old roof for this kind of thing? Or is it just asking for trouble?
Curious if anyone’s tried retrofitting extra support under an old roof for this kind of thing? Or is it just asking for trouble?
You’re not wrong about drainage being the real troublemaker. I’ve seen a few folks try to beef up old rafters for green roofs—sistering joists, adding posts, that sort of thing—but honestly, it’s rarely straightforward. Sometimes you end up chasing one weak spot after another. If the lumber’s already tired, you might just be delaying bigger issues. Still, with the right structural engineer and a realistic budget, it’s not impossible... just rarely cheap or simple. I get the eco appeal too, but sometimes “predictable” is underrated.
I hear you on the “predictable” part—sometimes boring is good, especially when it comes to roofs. I tried reinforcing my old shed roof a few years back, thinking I could save some cash and get a few more years out of it. Ended up spending more than I planned, and honestly, it still creaks every time we get heavy rain. If your roof’s already showing its age, sometimes patching just buys you time, not peace of mind. Still, if you’re handy and don’t mind a project, it can be worth a shot... just keep your expectations realistic.