Conservatory roof

[mikew]

Would it be possible for TB to explain more please. ie vent size, what insulation cellotx/the stuff in a roll, foil back plasterboard/plain.
Thanks

[The Builder]

If you go for cross-ventilation, Mike, it may be difficult if you have glass walls (you need to cut a through vent in two opposing walls....... it depends on how the conservatory is built.) I can't remember the size right now, but I can look it up if you decide to go that way.

Venting is only needed if water vapour (breathing etc) gets up through the plasterboard and the insulation, and condenses on the cold glass ....... which it certainly will.
Personally, I would avoid this by using the vapour check method that I mentioned earlier.

Tell me which you'd be happier with, and I'll get back to you.

[The Builder]

Also............... with the "sealed" method, you could use the existing roof rafters (beefed-up to carry the extra load.) This would mean that the top (hidden) face of the ceiling would be visible through the glass from outside............ so you may want to "blind" the glass in some way, to prevent this.

To create a vented void, you would have to fix a suspended, or an independent ceiling which could be flat i.e. non-slopey.