What is the best way to improve loft insulation

jimjames

We've just had an extension and I've had to sort the insulation for that to meet the 300mm building regs. The joists only allowed 200mm to sit between them so I've done a mix of using loft legs and additional joists at right angles to the existing ones. That gave me the total of 300mm with some air gap below the boarding that I then put on top.

Loft legs weren't too badly priced. I think I used 2 packs of them at £12.99 to do an area of around 3m x 2.5m. I'll see if I can get some photos of it to show setup.

I've also needed lots of Celotex as there's a room above the garage that needed insulating. I found an online supplier that delivered and beat any other price. It was http://www.insulationgiant.co.uk/ and the 50mm Celotex came out at £15.25 per sheet

Kernel_Sanders

I believe using polystyrene as insulation is illegal, because of its potential to poison firefighters.

Oneday77

I'm glad I stumbled in here. My loft is very similar.


The whole loft is about 64m2, with 32m2 of that floored with tongue and groove, nailed down. The sides that run into the eves have about 250-300mm of wool, so pretty insulated. The floored area has 50mm of old wool under it at best.
I'd considered Insulated loft boards on top of the flooring as the way the joists run, the ends are capped with the wool. The gable ends, I'd cut the boards back and fill to a decent level.
The loft boards though would get pretty expensive @ £12 each and I need 83 of them so I may consider the Kingspan with ply over the top now (thanks for the great tip)
My thinking is insulation is all about trapped air. If my floor is sealed, all the pipes, cables etc under it are left with breathing room, though still air but then the area above provides a more encapsulated insulation layer. All edges would be overlapped with an additional 100mm.


The loft has brick walls meaning the joist run is never more than 3m from support to support, so I don't think weight is an issue. However I want to avoid the upheaval of ripping up 32m2 of wooden flooring, to then have to buy more too.