I've managed to put this off for a year now but it looks like it's finally caught up with me and I'll be boarding the loft this weekend. Just had a thought though, do I need to leave expansion gaps between the boards in a 5 x 7 m loft?

Just approx 10mm around the perimeter, not between the boards

Just be careful not to compress the insulation (assuming there is any). Recommended thickness for insulation is now 300mm.

Cheers guys. I know there should by 300 mm of insulation but it's not going to happen. It's going to stay at 200. I think when I did the maths, putting the extra in would save about £15 a year. Considering how long we're likely to stay here, it doesn't pay for the timber! Still, the boards will have some insulating effect. No one every gives any credit to that.

Anyone got any idea what equivalent the boards offer? I had my loft boarded when we moved in two years ago, and although the guy doing it did say that the effect was 'substantial', I have often thought that he was talking out of his @rse. I've been toying with the idea of topping it up by laying an extra level of these or these.

What type of boarding have any of you used? And what price if you can remember?

i hate boarding lofts and mine needs doing. loads of insultation up there at the moment. Will have to be compacted to get the boarding down.

Its definately going to affect the insulation but I need the space.

Ho Hum.

If you're going to be compressing the insulation, then putting a sheet of Thermawrap under the boards could be useful.

Thermawrap from Screwfix

I used it to add insulation to my kitchen ceiling (and plaster-boarded it afterwards) and it is effective.

R = (1/K-Value) x (Thickness of material in mm/1000)

K for mineral wool = 0.04
K for chipboard = 0.15

18mm chipboard is equal to approx 5 mm of rockwool.

So boarding makes **** all difference!