Good points here, but honestly, I'd be careful about leaning too heavily on ambient temps alone. Sure, cloudy days can help with glare and even out surface temps a bit, but I've seen guys struggle just as much on overcast days if their welder settings aren't dialed in right.
In my experience, the real key is to regularly check your welds as you go—especially when it's hot out. If you're welding TPO and the surface temp is pushing 160°F or higher, you're probably gonna have issues with overheating and inconsistent seams. A quick tip: keep an infrared thermometer handy and spot-check the membrane every now and then. If it's getting too hot, adjust your welder speed or temperature accordingly.
Weather definitely plays a role, no doubt...but technique and equipment calibration usually make or break the job. I've had perfect welds on blazing sunny days just by slowing down a bit and tweaking the heat settings.
"keep an infrared thermometer handy and spot-check the membrane every now and then."
Yeah, totally agree—checking temps on the fly is a lifesaver. I've found even slight shade changes can swing surface temps pretty quick. Curious, do you adjust welder speed first or temp settings when things get dicey?
I've found that tweaking welder speed usually gives me a quicker fix when things start getting sketchy. Temp adjustments can be helpful, but they take longer to stabilize, and by then you might already have a compromised seam. If you're working in an area with patchy shade or clouds rolling through, it's easier to dial back your speed slightly and keep the heat consistent rather than constantly fiddling with temperature settings.
One thing I've noticed—especially on bright sunny days—is that the membrane can heat up way faster than you'd expect. Even if your infrared thermometer shows you're within range at the start, it doesn't hurt to check again after you've welded a few feet. I've seen guys get complacent because their first reading was good, only to realize later they've scorched the membrane halfway down the run.
Also, don't underestimate how much ambient heat from surrounding surfaces (like parapet walls or HVAC units) can affect your weld temps. Had a job last summer where we were welding near some reflective metal panels—temps shot up crazy fast, and we had to slow way down just to keep from overheating the TPO.
Speaking of which, what temp range are you guys typically aiming for? I know manufacturers usually recommend around 900-1000°F at the nozzle, but surface temps seem trickier to pin down consistently...
"Even if your infrared thermometer shows you're within range at the start, it doesn't hurt to check again after you've welded a few feet."
Yeah, good call on the repeated checks. I'm pretty new to this roofing stuff, but I've already noticed how quickly things can shift, especially midday. Honestly though, is surface temp really that critical if your nozzle temp is dialed in? Seems like there's a lot of variables at play here...but maybe I'm just overthinking it. Either way, appreciate the heads-up about reflective surfaces—hadn't even considered that yet.
Surface temp definitely matters, even if your nozzle temp is spot-on. Learned that the hard way a few summers back—thought I had everything dialed in perfectly, but it was one of those blazing July afternoons. The membrane was so hot you could practically fry an egg on it, and I figured my nozzle settings would compensate. Nope. Ended up with seams that looked decent at first glance but started peeling up after a couple weeks. Had to go back and redo a whole section...not fun.
Reflective surfaces are sneaky too. Had a job once where the building next door had these shiny metal panels, and they bounced sunlight right onto the roof I was working on. Temps shot up way faster than expected, and I had to keep adjusting my speed and heat settings on the fly. So yeah, checking surface temps regularly isn't just being cautious—it's saving yourself from headaches down the road.
