Suspended floor insulation

[df55555]

I have a suspended timber floor - onto which is being laid an engineered wood floor, probably one of the 15mm deep types and the skirtings are being fitted after the floor is laid.

Under the floor is quite a deep void and I am considering laying rigid foam insulation between the joists whilst I can still take up sections of the floor.

The question is how effective this would be for the amount of effort/cost involved. After the floor and skirtings are laid there should be no draughts coming through - so would the insulation be effective in making the floor feel warmer - ie would cold from under the floor have any imapct on making the wooden floor feel cold.

I guess I'm asking whether anyone has carried out this work and felt a major difference in heat loss of floor temperature.

 

[chuckalicious]

Can't answer your question but would like to add that I would also like to know the answer to this question (was just about to post the same thing!).

Would something like this product do the job, without increasing the risk of damp on the joists/boards?

http://www.diy.com/diy/jsp/bq/nav.j...efview=lister&ts=1249984016615&isSearch=false

 

[huw169]

Hi
I am doing the same thing at the moment. All my floor boards are up on the ground floor and I am clearing the crap from under the floor. I have about a 1.5ft gap under the joists which is full of builders crap.

If this sand & muck holds water, it will not dry out - especially if your wall vents are full off crap like mine were - 1930's built.

I will then lay in the radiator pipes with wrapped insulation, lay in the electrical cables, fix mesh to the underside of the joists and then drop in 100mm thick rockwool insulation (non-itchy stuff). This makes it easier to fill inconsistent spaces and the small gap between joists and the wall when they run parallel.

I can't comment on how much it will effect the 'comfort' of the house, but the cost and ease of rockwool make it more appealing to do. The solid Kingspan, or Celotex have more effective insulating properties, but the cost is prohibitive for me, and to try and cut every block so you get a good seal is not my idea of fun.
I think Wicks do a cheaper 100mm thick Polystyrene though.

Good luck - post up what you decide to do as my idea is not cast in stone yet....

 

[chuckalicious]

Since posting my bit in this thread, I read on the English Heritage site that when insulating under floors, between joists, you shouldn't use solid sheets as this is more likely to trap moisture and cause problems. Always use something like rock or glass wool. So, looks like you're doing the right thing.

Lifting the floor isn't an option for me so I'll need to lie on my back under the floor doing it. Bloody miserable job!