Hi everyone, I have recently moved house and found a fairly clear gap in my insulation under an extension. (Hence a freezing extension and kitchen.) The photos are of a log store under a bathroom and utility room, which seems to have no thought about insulation and exposed floorboards. From the looks of it, the larger space has never has any insulation and the other, smaller gap has some mineral wool stuffed under the floor, but nothing holding it up and another 2 foot of airspace to the ground. The joists are pretty much 400mm centres, and 120mm high. My plan for the large space is to fit Celotex from underneath and board it up with some ply. For the smaller gap I was thinking of putting more mineral wool in, where I can reach and put a vertical board over the wall with some air holes. Some questions: 1 - Should I go with 100mm (GA4000) or 120mm (XR4000)? 2 - Can I use 12mm Ply to panel it all off or should I be using 18mm everywhere? 3 - Should I attempt to re-fit all of the pipework up internally or use some pipe covers where they are? 4 - (And finally) for extra insulation, should I add something around or to the back of the door? Any advice would be great! Answers on a post(card) please. Thanks, Simon