Once that TPO gets up over 120°F, it’s a struggle to get a decent weld and not just make a mess.
I hear you on the early starts—by noon, my roof felt like a frying pan. I tried the silver tarps too, but they only helped a little. Has anyone tried using a temp gun to check the surface before welding? I’m wondering if there’s a sweet spot for surface temp, or if it’s just about working fast and hoping for the best.
I’ve used a temp gun a few times, mostly out of curiosity, and yeah—once it’s over 120°F, things get dicey. I found that aiming for early morning or late afternoon helps, but honestly, sometimes you just have to pause and wait for a cloud. The tarps never did much for me either. If you can keep the surface under 110°F, the welds seem a lot cleaner and less prone to bubbling.
If you can keep the surface under 110°F, the welds seem a lot cleaner and less prone to bubbling.
Couldn’t agree more—surface temp makes all the difference. I’ve had jobs where we’d start at sunrise, but even then, the membrane would spike past 120°F by mid-morning. Sometimes I’ll use a light mist of water on the surface before welding, just to knock temps down a bit. Not perfect, but it helps when clouds aren’t cooperating. Tarps never did much for me either... they just trap heat underneath half the time. Your approach sounds spot on.
I get the whole misting trick, but I’ve actually had mixed results with it. Sometimes the water flashes off so fast it feels like it makes the membrane even stickier, especially if there’s any humidity in the air. I’ve had better luck just dialing back the welder temp and slowing down a bit, even if it takes longer. Not sure if that’s just my setup, but for me, trying to fight the sun with water always felt like a losing battle.
Yeah, I hear you on the misting. I’ve tried it a few times and got pretty much the same results—just made the seam gummy and didn’t really help when it was blazing out. Slowing down and dropping the temp is what’s worked best for me too, even if it means babysitting the welder longer than I’d like. Honestly, fighting midday heat feels like trying to outsmart Mother Nature... she usually wins. Maybe there’s a sweet spot with timing jobs early or late, but that’s not always practical.
