"ambient temperature plays a bigger role than you'd think"
Definitely agree with this. I've done a fair bit of TPO welding myself, and ambient conditions can really mess with your settings. A few quick thoughts from my experience:
- Glossy spots usually mean you're running too hot or moving too slow. But like you said, if it's already hot outside, your usual settings can suddenly become too aggressive. I learned this the hard way too—had a perfect setup dialed in during spring, then summer hit and suddenly my seams were shiny and brittle.
- A good rule of thumb I've found is to start around 900°F to 1000°F on the heat gun and adjust from there. If it's a scorching day, I'll drop it down closer to 850°F and speed up slightly. It's all about balancing heat and pace.
- The airflow guide idea is solid. I rigged one up last year using some scrap aluminum flashing and it made a noticeable difference in consistency. Just make sure it's sturdy enough not to wobble around—otherwise, you'll be fighting it more than it's helping.
- Marking test strips is smart. I usually keep a few scraps handy and run quick tests whenever conditions change significantly (morning vs afternoon, sunny vs cloudy). Takes an extra 5 minutes but saves headaches later.
One other thing—don't underestimate the effect of wind either. Even a slight breeze can cool your weld area faster than you'd expect, forcing you to bump up the heat or slow down your pace slightly. It's subtle but noticeable.
Anyway, sounds like you're on the right track. Good luck with the airflow guide—let us know how it turns out.
"don't underestimate the effect of wind either"
Yeah, wind's sneaky like that... I've had days where everything seemed dialed in perfectly, then a random gust hits and suddenly my weld looks like amateur hour. Learned pretty quick to keep an eye on the forecast and set up some makeshift windbreaks if needed—plywood sheets or even parking the truck strategically can help.
Also, humidity can throw you off more than you'd expect. On muggy days, I've noticed seams sometimes come out weirdly inconsistent, even if temps are stable. Usually means tweaking heat settings slightly lower and moving a bit quicker to compensate.
And totally agree about marking test strips—saved me more times than I care to admit. I usually scribble notes right on the scraps with a sharpie (temp, speed, weather conditions). Looks messy but beats guessing later.
Anyway, sounds like you've got a solid approach already. Curious how that airflow guide holds up over time... aluminum flashing is clever but might bend easily if you're not careful.
Wind definitely caught me off guard the first time I tackled a TPO roof at home. Thought I had everything dialed in, but one unexpected gust and suddenly my seam looked like I'd done it blindfolded. Ended up rigging some old tarps as windbreaks—cheap and effective enough for DIY. Haven't tried aluminum flashing yet... seems smart, though I'd worry about durability long-term. Curious if anyone's tried heavier gauge flashing or another affordable alternative?
"Ended up rigging some old tarps as windbreaks—cheap and effective enough for DIY."
Tarps can definitely save your sanity in a pinch, but they flap around too much for my liking. I tried heavier gauge flashing once on a commercial property—held up surprisingly well against wind and general wear. Bit pricier upfront, but worth it if you don't want to redo seams every few years. Curious though, has anyone noticed a significant difference in weld quality between hotter and cooler days? Seems like temperature swings might affect adhesion more than we think...
I've noticed hotter days definitely make the welds feel a bit "stickier," but honestly, proper prep seems to matter way more. I had guys welding TPO in 90+ heat, and as long as we kept surfaces clean and consistent pressure, seams held up great.
