PeelsJohn

Way too late! Any way that wouldn't work as the roof skin is an essential part of the structure's rigidity. How harmful would it be to have the insulation up to the roof skin along side the rafters? Or would it be better to have the air space and some, but less than recommended, ventilation.

My conservatory has a lean to roof of plywood and EPDM. I am at the stage of fitting the insulation into the roof, and while I can keep an air gap open at the lower side, it will be nigh on impossible to have an opening at the top side for air circulation over the insulation. If I don't have air flow over it will I be better to have the insulation tight up to the plywood skin? I feel that with an air gap the air is going to fluctuate in temperature significantly, and there is potential for 'breathing' in plenty of hot moist air and condensing it overnight. If I have minimal air gap then I will have minimal moisture in there. I need some advice from someone with some experience of these matters, as all the advice seems to just say leave an air space and ventilate.

I am still building my conservatory, using hardwood and glass, the project is likely to continue for some time due to lack of same.