Draughty floor

[Twofingertyper]

Hi all,

I have a 1930s house with air-bricks around the base for air-flow purposes; when I bought the house these were blocked up by what I assumed was an error that the owner wasn't aware of.

Turns out he knew exactly what he was doing! Although stopping air-flow would have led to damage in the long-term, it did keep the house warmer and that was clearly what his idea was whilst he was attempting to sell! I am not going to cover up the air-bricks (I've read enough to know that this is a bad idea) but wondered about stopping the draught.

The carpet and underlay are both thick in attempt to keep the warmth, so he clearly knew it was an issue - but I wondered if there was something else that I could do stop the draught, I thought that a breathable membrane laid on-top of the boards and plush to the skirting, but below the underlay and carpet would be an option? A lot of what I've read talks about going under the floorboards; which is something that I'd really like to avoid if possible.

Advice appreciated!

TFT

 

[JohnD]

the draught won't be getting through underlay and carpet. it can get between bare floorboards though.

Is there a big gap under the skirting? Or holes for pipes and cables? Is there an open fireplace sucking air out of the room?

You can buy some joss-sticks and carry one round the room looking for the source of the draught.

 

[Twofingertyper]

Thanks for the response

You can definitely feel cold air around the floor near where the air bricks are - hence why my first thought is that the underlay and carpet are either not sufficient or not fitted properly.

There appears to be a gap under the skirting, but the carpet goes over this (like I said, it's quite thick); there is an open fire but the draughts from there are separate from the ones that I can feel coming from under the walls - not sure how common it is in older houses, but we had a side board against the wall at one point and when we pulled that out there was black mould behind it on the wall - lack of circulation for air?

 

[JohnD]

you could pack the gap under the skirting. If you are very lucky the gap will be even enough to use strips of wood or cork. Some people use expanding foam, but it will glue the wall, skirting and floorboards together. I prefer to take up the boards next to the wall and pack mineral wool between the last joist and the wall, or fabricate a way to stuff it between the ends of the joists but so it will not fall out.

the black mould indicates humidity resulting from poor ventilation.

when a draught blows through a carpet it leaves dark or black marks from the dust blowing in and sticking to the fibres. This is mostly round the edges of a room but if the boards are gappy you may see lines.

There should be air bricks on all sides of the house, so the air goes in one side, and out the other. If you have room to crawl under, you can do a good job.

 

[Twofingertyper]

Thanks - will take a proper look and see about filling the gaps; I was thinking that the membrane would have covered that and any gaps in floorboards (assuming I'd attach it to the skirting - and assumption that could be wrong!)

Semi-detached house, so have air bricks and the front and to one side, however, now slightly concerned as the house has had two extensions since the original build, and I can't see any air vents around the back...

Thanks again,
TFT

 

[AronSearle]

Stopping airflow may increase the risk of mould/condensation. All those gaps that the air blows in through can help if you have poor levels (or no) insulation.

See how you get on, making a significant difference may mean biting the bullet and spending proper time and money upgrading floor/wall insulation.

 

[dazlight]

Happened on a job I did few years back. We took Skirting off then filled the hole at edge of the floorboards to bricks with expanding foam. Worked well. Then used a good underlay for the laminate and full it up the wall 2 inch then skirts back on.