Filling non expanding foam into poly roof sheets

[diynob]

So an idea creeped in my head these past couple of days, might be the dumbest thing to creep up, might be something...

I have a conservatory with 25mm polycarbonate roof sheets on self supporting beams, classic conservatory kind of a thing. Tried to look online to change it to foam panels with aluminium or plastic coating, they cost two arms and three legs, so I started thinking: what if I fill the voids in the poly sheets with non expanding foam? Has anyone done it or tried doing it?! In my mind the foam is light enough to be worth considering (?) but it also plays out as a nightmare, probably with lots of small and long tubes it can be done...

Just lay it to me straight.

Thanjs.

 

[cdbe]

Bad idea, just underboard with PIR and clad with PVC cladding.

 

[diynob]

I've actually put on the multi layered foil and cladded on top, but the difference is not that massive. Thanks for the reply, PIR might just have to do, was just worried about weight though.

Presumably the PIR boards can be glued in place with some low modulus sealant/adhesive to make up for movement.

 

[cdbe]

I would screw timber battens to the rafters, friction fit the PIR then screw the cladding to the battens to hold the PIR up. It's generally held that the foil doesn't do much.