Insulating conservatory with Celotex - advice please

[ClareG1964]

Hi,
I have a bit of Celotex left over from a previous project and am thinking of using it to insulate our conservatory roof (the Celotex is only 25mm thick but I'll probably double it up). The roof is polycarbonate, with timber rafters. I'll cut the Celotex to fit snugly into the shapes made by the rafters.
Just wondering whether condensation would be an issue? Do I need to leave a gap between the Celotex and the polycarbonate? Or does the foil covering on the Celotex prevent any moisture passing through?
In case it's relevant, this is a small conservatory (10' x 9'), and I've never noticed any condensation in there at all (it never gets warm enough at the moment I guess!) We usually leave the small windows very slightly open.
Thanks.

 

[SittingBull]

Would it not look strange from the outside?

 

[UnluckyInBuyingHouses]

I HATE conservatorys. I have one on this house and its days are numbered! Some idiot wanted it, and maybe it was the same idiot that removed the doors between it and the house. I assume they where brain dead!

I have put 100mm celotex in the opening, and next year I will be removing the pointless conservatory and replacing it with a proper extension.

Maybe you should look at the replacement warm roofs for conservatorys that all the upvc companys are offering now. Its basically a light weight roof, 100mm polystyrene, 50mm celotex, and a plastic roof tile, all supported by an aluminium frame.

I gaurentee though, that if you get a quote for one it will make a certain lower opening in your body clench hard enough to turn coal into diamond!

 

[Time proved]

Thinking of doing the same to my hardwood framed glazed roof conservatory. Because the the supporting beams are a substantial depth I can cut and insert Celotex panels between them, and if need be, clad the foil surface with thin ply rather than us the plaster finish type. The point I would mention is the need for ventilation between insulation and glass but also to prevent infestation from flies, which is a real problem in summer. My solution is to fit flush fitting vents and on the back surface of the Celotex attach pieces of plastic fly screen to cover the vent apertures. These slim vents will need to be fitted both at the lower and upper sections (in the peak ) of the gabled roof between each set of rafters.

 

[Mike13]

When we had the conservatory I also used 100mm of celotex between the rafters in most of the roof, left a bit as is. It did help a lot.