Hi, Converting my loft into a room, had all plans drawn up with calculations by a structural engineer.on floor joist size, spacing etc. No dormer windows, just velux windows.Had building inspector round before I started today, he is saying height at from top of stairs to roof has to be 2m min, I have looked at guidance notes on other local authorities and they state 1.9m acceptable. Is that correct? I have a pitched roof, building inspector states there needs to be 50mm gap between tiles and celotex then celotex which would then be 50mm . Then a further 80mm celotex and then platerboarded, which is drastically reducing the headheight of the loft. Does this sound right? How do I work out the U value which would then tell me what insulation I require? The bloke who did my plans stated 70mm celotex then Triiso then platerboard. I know he is incorrect as ventilation gap would be 30mm and through reading guidance notes from other councils states 50mm. Any guidance would be much appreciated. Thanks
