Expansion of metal roof sheets

[Blr243]

On Saturday I installed insulated roofing panels on a deck ...this is maybe the 7 th or 10 th time working with this product I can’t remember , not necessarily the same manufacturer each time. 4100 mm span between support points ...I’m confident of the strength of this 50 mm foam product. All hesitation of walking on it fades the first time it’s installed Today when fitting the guttering in the midday heat I noticeD sighting along the top Of the sheet/ ribs ( it’s the trimdek style profile) and it’s not straight. It’s curved. Not bowing down. It’s bowing up. Wtf Bowing down would be worse. It would look like the product is not up to the task. I never seen this before Only thing I can think of is the tropical Brisbane temps are heating up the top and as it expands it grows in length and somehow bows up. Remember the bottom tin sheet is cool What do u reckon. Why is it bowing up ? I intend trying to get a look at it early one morning when it’s cool. Otherwise the customer is very happy and it looks great

[Ziege]

Ive seen it bow out a tiny bit but nothing a customer would notice and ive done hundreds of them. my assumption is the better the foam is sealed to the colourbond or baked enamel the more it bows, foam like in Styrofoam is 90+% air, so makes sense that it can expand.

[Die Judicii]

It's a no brainer.
Being cool on one side and flaming hot on the other side, it's got no other option but to expand and bow.

If the roof iron didn't have the insulation sheets attached to it you wouldn't see it move so much.
Being Trimdeck profile,, (large flat areas) as opposed to constant curves as in conventional roof iron,,, it'll "move" much more so than the latter.

I would surmise that maybe just trimdeck on its own, then airspace, then insulation seperately attached might be the only way to stop it completely from bowing.

[Blr243]

It would be interesting to measure one at night vs one at midway to check it’s growth. But I can’t now that flashing is in the way. I have other sheets at home I can try. I’ll do it now

[Blr243]

I had another look at that roof this morning and it was still cool and only a very small bow. So it’s definitely the heat causing the bow