Clearance beneath floor joists

[honeymonster1986]

Hi, first post to the forums, but reading them has already been a massive help!
Looking to insulate beneath a suspended timber floor and wondering how much clearance there should be beneath the joists. We've got about 24cm clearance at the moment, but considering draping netting to hang beneath the joists so we can fit more insulation in.

Will the insulation affect the air flow beneath the floor significantly and cause problems. There should still be about 17 cm space between the netting and the subfloor.

Thanks

 

[stuart45]

150mm min.

 

[HERTS P&D]

Just insulate the depth of the joists, anything else would be a nightmare to do unless you could crawl under the floor.

Andy

 

[honeymonster86]

Thanks both for your replies. Was keen to get 170mm in for the extra insulation values, 100mm would give 2.25 R-value. i guess dropping it into the gap would provide perfect cover as there would be gaps between the joists.

 

[maltaron]

Apart from the clever b*****s who write the building regs, who would have thought it necessary to insulate under floors. Simple physics says "heat rises" The only advantage in insulating floors is to stop drafts if the floor is to be left as boards, otherwise carpets will be more than enough. Also any insulation under the floor will restrict air flow around the joists which could result in dry rot.