Interesting points here. I've been leaning toward EPS myself mainly because of budget constraints, but now you've got me thinking twice. Did you have any vapor barrier installed along with the EPS, or was it just the insulation itself? Wondering if adding a barrier might've helped with the moisture issue... seems like climate plays a bigger role than I initially thought.
I had a similar moisture issue when I first went with EPS on my flat roof. Initially, I skipped the vapor barrier to save a bit, but ended up regretting it. After adding a proper vapor barrier later, the moisture problems pretty much disappeared. So yeah, climate definitely matters, but a barrier can make a huge difference. You're on the right track thinking about that... better to tackle it upfront than deal with headaches later.
Had a similar experience on a job a few years back—client insisted on skipping the vapor barrier to cut costs. Told him upfront it was risky, but he wanted to roll the dice. Sure enough, moisture issues popped up within a year. Ended up having to tear off sections and redo it properly with a barrier. Climate matters, yeah, but honestly, I've seen moisture problems even in drier areas without proper vapor control. EPS is decent insulation, but it's not foolproof on its own. Better safe than sorry... learned that lesson the hard way myself.
"Climate matters, yeah, but honestly, I've seen moisture problems even in drier areas without proper vapor control."
You're spot on with this—I've encountered similar issues even in regions you'd least expect moisture to be a problem. EPS is solid insulation, but like you said, it's not a standalone solution. One thing I've found useful is combining EPS with a cover board like gypsum or densdeck for added protection and durability. Curious if anyone here's had good experiences using cover boards alongside EPS on modified bitumen roofs?
"EPS is solid insulation, but like you said, it's not a standalone solution."
Totally agree with this point... EPS alone can leave you vulnerable. I've seen gypsum cover boards really help with durability, especially on mod-bit roofs. Haven't tried densdeck yet though—worth the extra cost?
