the real issue isn’t just the air temp, but the surface temp of the TPO itself
That’s spot on. I tried patching a seam on my garage roof last August, and even at 8am, the TPO was already roasting. I thought I could tough it out, but my knees were practically sizzling. I’ll admit, I cheaped out and skipped the infrared thermometer—bad move. Ended up redoing half the welds because they just peeled up later. Next time, I’m waiting for a cloudy day or at least spring temps. Not worth the hassle (or the sunburn).
I’ll admit, I cheaped out and skipped the infrared thermometer—bad move.
Yeah, skipping the temp gun bites later. Even if air feels fine, I’ve seen TPO hit 140°F by mid-morning in summer. Welds just don’t hold right when the membrane’s cooking. I usually shoot for early morning in spring or fall, or like you said, cloudy days. And kneepads... not optional when it’s hot.
I’ve definitely been there, thinking I could just “feel” if the TPO was too hot, but yeah, that surface temp sneaks up fast. I’ve had welds look perfect, then peel right up a week later—super frustrating. Curious if anyone’s tried those reflective tarps or temporary shade setups to keep things cooler? I’ve only messed with them a couple times, but not sure if it really made a difference or just felt like wishful thinking...
Curious if anyone’s tried those reflective tarps or temporary shade setups to keep things cooler? I’ve only messed with them a couple times, but not sure if it really made a difference or just felt like wishful thinking...
I’ve tried using a reflective tarp once when we were working on a school roof in July. Honestly, it felt cooler under there, but I’m not convinced it actually kept the TPO much cooler—maybe just made it less miserable for us. The welds still seemed tricky. I did notice the seams didn’t get as glossy, though, so maybe it helped a bit? Hard to say if it was worth the hassle dragging that thing around all day.
I get the appeal of those tarps, but honestly, I’ve never seen a huge difference in the actual TPO temp—maybe a few degrees, tops. What’s helped me more is starting super early and keeping the material shaded until right before welding. Once the membrane gets over 120°F, it’s just a pain no matter what you do. The seams can get weirdly glossy or even bubble if you’re not careful. If you’re stuck working midday, I’d say focus on keeping your tools and rolls out of direct sun as much as possible. The tarps are a hassle unless you’ve got a big crew.
