Insulating under carpet

[b21playa]

Hi all

I’m wondering if someone can help/advice me please.

I have a 1920s house with suspended timber flooring. A lot of work needed to be done but with the cold starting to set in I’m looking to sort one of the rooms downstairs temporarily for my elderly mum due to go through treatment shortly…she is really feeling the cold and only to get worse with her treatment.

I have old rubber underlay with cheap carpet from previous owner on top. The rubber has disintegrated and the room is very cold, so looking to replace the underlay (I have some 11mm cloud 9 left over) and relay the carpet on top. The question is, can I or is it worth adding a foil type underlay under the cloud9 to provide additional insulation properties? Plan was to empty the room, foam around the perimeter between skirting and floorboards to stop cold, foil back the entire floor, then lay the grippers and underlay before putting the carpet back.

Is it worth adding a foil product underneath or would it be a waste of time?

Many thanks in advance for any advice or suggestions…it is much appreciated.

 

[JohnD]

Heat loss from a wooden floor is mostly by cold draughts, which are worst through the gap under the skirting, especially against external walls.

The other draughts between floorboards are easily blocked by any kind of carpet or underlay.

If you are handy, you can take up the floorboards against the wall, and pack the space between the joists and against the wall with mineral wool loft insulation, which is very easy to use as it does not need to be accurately cut. Sometimes the boards will previously have been taken up for cables or radiator pipes and are easier to lift. Screws are easier than nails. You must not block airbrick ventilation.

If not, you can clean out the gap under the skirting boards with a stiff brush and hoover, and pack it. I have seen cork strips and silicone sealant used.

If the skirtings are coming off, you can run expanding foam in the gap, but you must trim it for the carpet.

It is possible to lift the entire floor and insulate fully, but this is a lot more work unless the floor is coming up for some other reason.

 

[b21playa]

Heat loss from a wooden floor is mostly by cold draughts, which are worst through the gap under the skirting, especially against external walls.

The other draughts between floorboards are easily blocked by any kind of carpet or underlay.

If you are handy, you can take up the floorboards against the wall, and pack the space between the joists and against the wall with mineral wool loft insulation, which is very easy to use as it does not need to be accurately cut. Sometimes the boards will previously have been taken up for cables or radiator pipes and are easier to lift. Screws are easier than nails. You must not block airbrick ventilation.

If not, you can clean out the gap under the skirting boards with a stiff brush and hoover, and pack it. I have seen cork strips and silicone sealant used.

If the skirtings are coming off, you can run expanding foam in the gap, but you must trim it for the carpet.

It is possible to lift the entire floor and insulate fully, but this is a lot more work unless the floor is coming up for some other reason.

Thanks John.

Unfortunately don’t have the time to lift up all boards to insulate; that’s would be my ideal but not possible at the moment. I have about a day or two to get this job done in between other commitments.

Skirting boards are being kept but there does seem to be gaps around the edge (well above air bricks) so this is where I thought the expanding foam might help with the drafts. The foil idea was just something I thought could help and would be easy enough to lay while the room was empty

 

[big-all]

i really really would be reluctant for any claims for insulation as most in this country seem to be based on approval for one situation extrapolated to a near match or similar to another and called approved without further test then extrapolated again for another situation and again approved as several cladding "experiments " getting more and more remote and wildly different have proved over the last probably 20 years pre Grenfell and since no insulation information can be trusted unless the original manufacturer has his name on the pass and compliance certificate and then can we believe it fully ??
may seem a heavy comment but profit seem to be worth more than lives over the last at least 15 years perhaps longer and yes i know flammable foam is different to foil so know the fire danger is not there but the dodgy claims may be there ??so would expect foil wont work well without high levels off heat like a hot radiator or body heat so pointless on a floor where other insulation will exclude draughts