I am having the floorboards replaced downstairs as I am having t+g chipboard installed. The floorboards were quite badly damaged by woodworm. As I am taking up the boards, are carpenter recommended we insulate between the joists we celotex. We have insulated above we Rockwool. Is insulating under the floor common? I have never heard of it before. If it will help keep the house warm, guess it makes sense to do whilst the boards are up. Any advice would be appreciated. Thanks IM
Yep. I've used GA4050 to insulate the entire downstairs suspended timber floor in my house. It's an easy task and the floor level feels much warmer underfoot in winter. The insulation should be no more than 50% of the depth of the joists to allow decent airflow to the wood in order to avoid rot.
Thanks fella. I am thinking of using celotex. They have the 100mm option. So I have to ensure the insulation is wedged halfway up the joist? Do you wedge it in like you do with Rockwool?
No. Level it flush with the top of the joists (so that your flooring will sit directly on top of it with no gap). How deep are your joists? The thickness of the insulation should be no more than half the thickness of the joists. As an example, 100mm depth joists should have 50mm depth insulation between them.
I prefer to set the the insulation about 30mm - 40mm below top of joist so you got space to run electric cables,etc, but other peeps like insulation flush.
I use tile batten cut into short lengths about 300mm - 350mm & fixed to side of joists, with a 12' joist I would use usually four pairs for Celotex to sit on.
Thanks KIAB. My preference is to attach it the most simple way. I am guessing applying an adhesive then putting the celotex between the joists would be the most simple strategy. Have also seen some people use tape.
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