Fred

In the wake of the changes to Part L of the UK Building Regs insulation manufacturers are making all sorts of claims and counter-claims about their products - just do a search for "Roof Insulation" Archisearch.co.uk to see what I am talking about. Some people claimed that the foil type insulations were only effective if they were kept clean to enure that they reamin effective and the BBA held back on issuing certificates for this type of system for some time, however the first certificate has now been issued, see http://www.bbacerts.co.uk/certs/43/4379.html I'm not greatly reassured by BBA certificates myself (they seem to issue them to anyone who sends them £30,000 these days). However as this type of product has been a hot topic of debate I'd imagine that the'd have done their homework on this one.

I've been considering a similar project - except that I want to dig a completely sunken cellar in the garden and top it off with a green roof. I am assuming that if I insulate it enough the temperature fluctuations will be low enough to allow me to store wine(I am looking to purchase a property near Tours so it can still get quite cold in the winter). I have found a detail (Example 1) on this basement waterproofing site which is obviously intended for a much larger basement. I could probably get away with some more rudimentary waterproofing as a little damp in the cellar won't harm the wine. Another website that I have found useful is the British Earth Shetlering Association.Although it doesn't have much technical info it gives some good ideas about what can be done.