Flooring a Loft

[Jacka]

Hi all

I'm just after a little advice.

I have a 1960s Semi detached house, which had an extension built over the garage 10 years ago. As it's separate from the main loft and an unused space, I would like to convert it into either a storage area or play room for kids. There's not loads of head room but it would be enough. It has 2 layers of thick insulation and that covers the joists, but I don't wish to strip any of it out as it's a cold house and I plan on tackling the main loft from an insulation point of view next year (it's boarded with 2/3 inches of insulation).

My question is.... could I replace the insulation with say an insulation board and would that give the same thermal qualities as the insulation that I have? By doing this I could use existing joists

or if I can't and have to make a suspended floor, would I get away with 4 x 2 inch joists?

Any help would be appreciated

Thanks

David

 

[endecotp]

For light storage, it's possible to have mineral wool between the joists and then lay solid insulation panels across the top of them, then chipboard / ply. See e.g. http://www.celotex.co.uk/download/b35a44bf-dbb4-46b8-aae0-23cde298e605

Celotex is approximately 50% better thermally for a given thickness than mineral wool.

 

[JohnD]

lay solid insulation panels across the top of them, then chipboard / ply.

Knauf (I think) issued a how-to-do it video for that, but then they discontinued the product. I thought it a very good method. Will see if I can track down the video.

edit
can't find it but here is a DIYer doing it

edit again

I did mine by cross-battening at right angles to the original joists, and laying mineral wool between both lots to give me a total wool thickness of about 220mm, but I think the foamed board is better, and saves carrying and cutting the timber.

The batten method does spread your weight better and add stiffness, when all tightly screwed together.

 

[Jacka]

Thanks for that! I didn't know the boards were thermally better than Rockwool!

It won't give me the flexibility if I want to make it into a playroom. May have to rethink strategy!

 

[Jacka]

Cheers John