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Is it ok to insulate the ground floor, floor meaning under the fllor boards, job done under the house, in order to stop any drafts.

3 Answers from MyBuilder Insulation Installers

Best Answer


Hi you can put it in, but you also need ventilation for the ground floor joists, otherwise you can create the ideal conditions for dry rot. So it tends not to work well in that application or for stopping drafts. Heat rises, hardly any escapes a building down wards.

You'd be better off filling the gaps in the boards, to stop the drafts and make the building warmer!

Hope this helps


Answered 16th Jan 2012

Guessing it's an older building?

Any carpenter that went to college, will have been taught that insulation isn't a good idea in ground floors, because ground floor joists need ventlation to stop dry rot/wet rot(insulation causes condensation). So if you do put it in, you still need adequate ventilation, which won't stop your draft or insulate much.

Heat rises out of a building, hence the reason the goverment has jumped on fill your walls/ loft insulation doesnt travel down and out the ground floor, otherwise they'd soon jump on that as well. Anything to make people waste money basically.

Better off to fill the gaps in the floor or put carpet down etc.


Answered 23rd Nov 2011

Yes you can insulate between the floor joist, use kingspan solid insulation boards.
Check if you have vents under floor, that they are clear and you have a good air flow.


Answered 23rd Nov 2011

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