- Spray foam under mod bit? Yeah, seen that go sideways a few times myself. Moisture trapping is no joke—once it's in there, good luck drying it out without tearing everything apart.
- Mineral wool's decent from what I've seen, but honestly, installation quality makes or breaks it. Had a job a couple years back where the crew wasn't familiar with it... ended up compressing the insulation too much, killed the R-value. Owner wasn't thrilled when winter rolled around.
- Polyiso is usually my go-to as well, despite the quirks you mentioned. It's predictable and most crews know how to handle it. Just gotta watch out for storage issues—leave it sitting outside uncovered for a week in rain and you're asking for trouble.
- One thing I haven't seen mentioned yet is cover boards. Whatever insulation you pick, throwing down a good cover board (like gypsum or HD polyiso) can save you headaches later on. Seen plenty of roofs survive hailstorms just because they had a solid cover board layer underneath.
- Bottom line: no insulation type is bulletproof. It mostly comes down to proper detailing, good workmanship, and regular maintenance checks. And yeah, keeping an eye on flashing details—seems like that's always the weak spot, no matter what insulation you're using...
Totally agree on the cover boards, they're underrated. When we redid ours, adding gypsum board underneath was a lifesaver—hailstorm hit last spring and neighbors had leaks everywhere, but ours held up fine. Worth every penny in my book.
Interesting point about gypsum boards—I've been researching insulation options myself, and I'm leaning towards polyiso foam boards for their higher R-value. But now you've got me thinking about durability too, especially with hailstorms being common around here. Did you install the gypsum directly under the membrane or sandwich it between insulation layers? Curious how that affects moisture control and overall roof longevity...
I've been wondering about gypsum placement too, especially since moisture buildup can be a real headache. If you sandwich it between insulation layers, wouldn't that trap moisture more easily? Or does the gypsum actually help wick moisture away somehow? I'm trying to balance cost and durability myself, and the last thing I need is hidden water damage down the road...
"If you sandwich it between insulation layers, wouldn't that trap moisture more easily?"
That's exactly what I thought initially. A few years back, I renovated my flat roof and went with gypsum cover boards between insulation layers, thinking it'd add durability. Turned out, moisture did become an issue—nothing catastrophic, but enough to cause concern. After consulting a roofing specialist, I learned gypsum doesn't really wick moisture away; it's more about fire resistance and structural stability. Proper vapor barriers and ventilation ended up being key to avoiding hidden moisture problems down the line.
