OK, daft question coming up. I think the optimum depth of insualtion would be deeper the beams in the loft. I want to floor the loft for additional storage. I think if I just get the flooring sheets from B&Q and lay them accross the beams compressing the insulation that will at least partially negate the effects of the insulation. So how do I easily lay the flooring without compressing the insulation? Thanks.

batons on the beams to raise them ? – i hope thats the correct method as thats what i wanted to do !

I only had 100mm depth in my loft joists. So I boarded the loft over glass wool. Then put down celotex / kingspan, then another board over the top.

The total insulation is now greater than the equivalent of 270mm of glass wool.

Joists running at 90deg to the existing ones tied to the existing joists with some of these then lay the floor sheets on the new joists.

you could even fill the void beneath the flooring boards with extra insulation if there is room

compressing the ins will make it work roughly the same as ins at the reduced thickness

b&Q do stilts to raise the boarding up;

http://www.diy.com/nav/build/insulation/loft-insulation/loft_storage_stilt/Diall-Loft-Storage-Stilts-12-Pack-11837507

cheap, light – what’s not to like?

wwaswas – they look like something a rubbish DIYer like me could manage.

Thanks everybody.

Toolstation do some more substantial legs if you want to go that way, but I used this for the part of the loft I wanted to use for storage.

I had a question like this recently that I posted on mybuilder.com. They this an ‘Ask a Tradesman’ section which is quite helpful because tradespeople are the ones who answer your questions (instead of people like us that actually don’t have a clue :/).

http://www.mybuilder.com/questions

cellotex sheet over the joists then screw your board through cellotex into joists.

be careful with your ventilation.