"Personally, I'd say slope and drainage are your first priorities, then insulation and sealing."
Couldn't agree more on this point. I've seen too many flat roofs turn into mini swimming pools after a heavy rain—definitely not the kind of rooftop pool anyone dreams about, haha. Seriously though, slope and drainage are critical. Even the best insulation won't hold up if water's constantly pooling above it.
Rigid foam is solid (pun intended), but like you mentioned, prep is everything. I've had to rip out foam boards that weren't sealed right, and trust me, it's not fun. One thing I'd add is to consider a cover board over the insulation layer. It adds durability and protects the foam from foot traffic or accidental punctures during maintenance.
Ventilation channels can be helpful, but honestly, if your sealing and drainage are dialed in properly, they're usually just extra insurance. Still, if you're in a humid climate or have had moisture issues before, they might be worth the peace of mind.
Good points all around. I've seen cover boards save insulation from some pretty careless foot traffic, so that's definitely worth considering.
"Ventilation channels can be helpful, but honestly, if your sealing and drainage are dialed in properly, they're usually just extra insurance."
True enough—though I've come across a few roofs with solid sealing that still had moisture issues down the line. Makes me wonder...have you found any particular membrane or sealing method holds up best long-term with modified bitumen?
From what I've seen, torch-applied SBS membranes tend to hold up pretty well long-term...provided the installer knows their stuff. Still, even the best sealing won't fix underlying moisture issues—like you said:
"I've come across a few roofs with solid sealing that still had moisture issues down the line."
Always worth double-checking drainage and flashing details before relying solely on membrane choice.
Good points all around. I've dealt with a similar issue on my place—had a modified bitumen roof put in about 8 years ago. Membrane's held up great, but we still had condensation problems until we sorted out ventilation and insulation. Ended up adding rigid foam insulation boards above the deck, which made a huge difference. Just make sure to get the detailing right around edges and penetrations or you'll still get moisture sneaking in... learned that the hard way.
"Just make sure to get the detailing right around edges and penetrations or you'll still get moisture sneaking in... learned that the hard way."
Yeah, that's always the tricky part. I've seen rigid foam boards work well, but I'm still skeptical about their long-term durability—especially around HVAC units or skylights. Did you use any special flashing or sealants to keep moisture out? Curious if anyone's had luck with spray foam insulation instead... seems like it might handle irregular surfaces better.
