- 130°F seems about right, but I’ve seen some crews push it up to 140°F without disaster—depends a lot on the membrane brand and color.
- IR thermometers are a game changer, but I still do the “back of the hand” test out of habit.
- Shade tarps... yeah, those are more trouble than they’re worth if there’s any wind. Nearly lost a clipboard once.
- Early mornings definitely help. I’ve also noticed welds hold better if you can avoid direct sun glare, not just the heat.
- For anyone tracking warranty claims, I’d document surface temps before starting—manufacturers love that kind of detail if there’s ever an issue down the line.
Had a job last July where the roof temp hit 138°F by 10am—white TPO, but the sun was just relentless. We tried to push through, but the seams got a little sketchy. The welds looked fine at first, but a couple days later, we had some fishmouths pop up. Ended up redoing a section. Since then, I’m a lot more cautious about that upper limit. I’ll use the IR gun, but honestly, I still trust the back of my hand more than any gadget. If it feels like you can’t keep your hand on it for more than a second, it’s probably too hot for a good weld.
Shade tarps are a joke in Oklahoma wind—one gust and you’re chasing tools across the parking lot. I’ve had better luck just starting at sunrise and calling it quits by noon. And yeah, documenting temps is a lifesaver if the manufacturer ever comes sniffing around about a warranty. Learned that the hard way after a claim got denied because we didn’t have proof of surface temps.
That’s wild—138° by 10am is brutal. I’ve had similar issues with welds looking fine at first, then failing after a couple days, especially when the surface temp gets up past 130°. Have you ever tried using a temp log sheet or even snapping a quick photo of the IR gun reading for documentation? I’ve heard some folks swear by those little temp stickers you slap on the membrane, but I’m not sure how reliable they are in direct sun. Curious if anyone’s found a method that actually holds up for warranty claims without slowing the crew down too much.
We’ve run into the same issue with TPO welds not holding when it’s pushing 135° or more on the surface. I’ve tried those temp stickers, but honestly, they tend to turn black in direct sun and aren’t always accurate. What’s worked best for us is snapping a photo of the IR thermometer right before welding—quick, easy, and it timestamps everything for the file. It’s not perfect, but it’s saved us on a couple warranty claims when things got dicey with the manufacturer. Still haven’t found a method that doesn’t slow down the crew at least a little, though.
What’s worked best for us is snapping a photo of the IR thermometer right before welding—quick, easy, and it timestamps everything for the file.
I’ve done the same thing with my little $30 IR gun—honestly, those temp stickers are useless in direct sun, like you said. I get nervous when the surface temp creeps past 130°, especially on white TPO. Even with the photo backup, I still end up waiting for clouds or hosing down the area to cool it off. Slows things down, but I’d rather have a solid weld than redo it later. Never found a magic fix for the heat issue... just gotta work with what you’ve got sometimes.
