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Draughty walls

tommer71

Hi , I have an issue with draught coming from behind my skirting board, would taking them off and spraying expanding foam into the void behind work ?, it’s dry lined on a 9 inch cavity block wall, the attic is spray foam insulated, also it’s a bungalow,any help would be appreciated

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MicktheMan

No, expanding foam is a filler, not a sealer.

You need to apply air tight tape to the floor to wall junction and refit the skirting. Make sure the surfaces are properly prepped etc (which may involve using a primer or air tight mastic depending on the substrate).

Doing this will have a big impact.

loyatemu

I have the same issue - would filling the gap under the skirting have the same effect?

10-10-20

At the end of the day the expanding foam might be the right solution if you're looking to fill a gap and reduce the air-flow into the livable space and you don't have the resources or finance to address the whole solution. I don't disagree with MicktheMan at all, but air-tight tape isn't the first thing that I'd reach for if I was trying to stop a draft from a skirting board. Basically the drylined wall should have been air-sealed at the point of install.

https://www.boards.ie/discussion/comment/119958952#Comment_119958952

Use a low-expanding foam, otherwise you may encounter other issues.

tnegun

If you do go the expanding foam route have a read of this first https://www.boards.ie/discussion/2057312010/expanding-foam-explosion-house-ruined

loyatemu

https://www.boards.ie/discussion/comment/119959776#Comment_119959776

cheers - I note CharlieDIYte has a video where he uses this product to fill the gaps under his skirting boards. Might be worth a try, I'm not keen on taking them all off.

As for the kitchen cupboards, I've seen suggestions of filling under them with rock-wool type insulation. I'm not sure where the draught is originating from, it could be a gap where the pipes emerge or possibly it is coming down the walls. The room is insulated (it's an extension and it's the only properly insulated bit of the house) but I can see under the cupboards that the plasterboard doesn't come all the way to the ground...

10-10-20

https://www.boards.ie/discussion/comment/119959819#Comment_119959819

That expanding tape is good, cleaner to use and less risk than expanding foam, but it's not going to fill the holes where the cold air is percolating up from.

MicktheMan

The origin of the leak at the floor to wall junction is immaterial, be it from unsealed plasterboard, through unsealed block work, through unsealed stud work in timberframe, through the junction gap around turned up radon / damp proof membranes matters not a whit, it is the stopping of this air from entering / leaving the room that is relevant here.

Using air tightness tape will solve this issue for good and if done properly there should be no sign of the work when the skirting board is put back in place. All other methods such as foams, sealants etc, while okay maybe in the short term, will need to be revisited regularly plus also bear in mind that not only the bottom of the skirting board but also the top needs to be sealed if not using the tape method.

tommer71

Where would I start to look for problem or is a needle in a haystack type of thing

10-10-20

What's the construction of the floor?

tommer71

Would the tape be okay put over a void or would I have to plaster in the voids / uneven slab

MicktheMan

https://www.boards.ie/discussion/comment/119960851#Comment_119960851

Not sure exactly what you are asking here but if it is where to start to tackle heat losses in a meaningful way you won't go wrong with a good heat loss survey which includes a pressure test of the house.

MicktheMan

https://www.boards.ie/discussion/comment/119961485#Comment_119961485

How you tackle it will depend very much on the type of floor and wall you are dealing with but in general:-

When taping, it is important to pay attention to the substrate you are taping onto. It obviously needs to be clean, dust free etc etc but it also needs to be sound so if a void exists you bridge the void with multiple rows of tape or a combination of tape and membrane such that there is a continuous seal between the wall and the floor. If surfaces are rough or uneven then run a continuous horizontal line of air tight mastic on the wall or floor first before applying the tape will help take the undulations out of the equation.

tommer71

Many thanks for your help and knowledge I will get some mastic today as the plaster is cracked at the bottom ,it’s on a engineered floor , the skirting is 7 inch , so I’m going to put 6 inch tape from wall to floor,

tommer71

I have noticed that the plaster slab did not go all the way down to the floor , so I slabbed down to floor level and skimmed it and going to put air tightness tape on when fully dry, also noticed small amount of air coming through the electrical sockets, it’s the house that just keeps giving

MicktheMan

https://www.boards.ie/discussion/comment/119964462#Comment_119964462

Yes sockets, switches will all leak air (any penetration really of your walls, ceilings are likely leakage points, even internal ones depending)

tommer71

Is there anything I need to do in the attic, to try stop the air coming in

MicktheMan

https://www.boards.ie/discussion/comment/119964696#Comment_119964696

No, other than sealing recessed lighting fixtures if present to the ceiling in the attic there is nothing that can be done.

General rule of thumb 1; you deal with air leakage from inside the space / room (the attic is outside the thermal envelope)

General rule of thumb 2; the air tight barrier layer should always be on the warm side of the insulation layer

tommer71

https://www.boards.ie/discussion/comment/119964649#Comment_119964649

On closer inspection of the attic I have seen where the genius of an electrician had cut a 4 inch hole in the spray foam insulation, from the facia board , front and back , so mystery solved, I hope, Micktheman, thank you very much for your time and advice, a gentlemen

loyatemu

https://www.boards.ie/discussion/comment/119959819#Comment_119959819

spurred on by how freezing my kitchen was today I took off the kickboards and went looking for the source of the draught. I reckon this outlet from the sink/dishwasher is the culprit - it just disappears into the exterior wall and there appears to be a bit of a void below it as well. I used my infra-red thermometer on it and it read 11C, the rest of the room is around 20C. The further I go from the hole the higher the temperature is but there's a cold draught blowing out from under the cupboards and skirting all the way around the room and the floor is cold as a result.

I checked where the pipe comes out outside and it is sealed up but I assume the hole in the wall goes outside the insulated layer so air is getting into it anyway. Short of ripping out the kitchen cupboards to seal it up, is there any other solution?

10-10-20

Pack it with glasswool. I know it's not a moisture barrier but at least it's removable and isn't going to attract rodents.

loyatemu

https://www.boards.ie/discussion/comment/119969003#Comment_119969003

Pack around the pipe (it's pretty inaccessible) or under the cupboards?

Anything to be said for expanding foam around the pipe if I could reach it?

10-10-20

https://www.boards.ie/discussion/comment/119969548#Comment_119969548

Around the pipe. Use a blunt rod to push it, you'll find that the rod catches the wool and helps force it in.

A lot to be said about expanding foam, but I don't think it's necessary here as that joint may need to be disassembled and foam can take over. Up to you entirely, but use what you have handy. 👍️

MicktheMan

https://www.boards.ie/discussion/comment/119969548#Comment_119969548

Expanding foam is a filler, not a sealer.

@10-10-20's comment on packing the fibre into the gaps is the one to try. Also, don't forget the other floor to wall gaps under there no matter how small or insignificant looking.

The Continental Op

https://www.boards.ie/discussion/comment/119969548#Comment_119969548

I'd think about filling the whole area with glass fiber insulation then get a 100mm Kingspan type insulation board and cut it down so it fitted just behind the kicking boards all the way around the kitchen. If necessary I'd seal the kingspan in place with foam or you could set it back and seal with tape. Then if you do need to get under there you are cutting away material at the front of the cabinets not the back. But if the draught comes up the back of the cabinets that will only help a bit.

GreeBo

https://www.boards.ie/discussion/comment/119972098#Comment_119972098

Foam is a filler alright, but it will "seal" a large gap enough to prevent wind, it wont be airtight, but it doesnt need to be to stop a draught.

On the original question regarding skirting, a quick and easy approach is to just caulk the boards top and bottom, this just prevents the breeze for entering the room, but its still going somewhere (probably an open cavity wall in the attic) but its a lot simpler than getting into skirting removal etc.

monseiur

If wall are slabbed on 2 x 1'' vertical laths I would hazard a guess that the draught is coming down the channels between laths from the attic, unless of course you have timber floor with a void under them😒

MicktheMan

https://www.boards.ie/discussion/comment/119974502#Comment_119974502

Tho whole point of doing this is air tightness so using a material that inherently will not give an airtight solution (especially after it shrinks over time) is not the best approach I would have thought. Im my experience, using well compacted fibre will give a far better solution especially over the medium to long term and is safe in the sense of no chance of adverse chemical reactions between the foam and cable housing if cabling present.

Using caulk is perfectly fine for one heating season (i.e. very short term) due to the seasonal expansion / contraction of the different elements but will need to be addressed at least bi-annually, if not annually depending. It can also look a tad messy depending on the finishes. I know that if I was doing this I would want to do it once and not have to worry about it again!

MicktheMan

https://www.boards.ie/discussion/comment/119974600#Comment_119974600

.... or coming from the cavity either through where the floor joists upstairs are mounted or through the unsealed blockwork (concrete blocks and mortar joints are porous to air). Or all or some of the above.

The point is that it doesn't really matter whether the path of the air from outside is direct or indirect, what matters is that there is a continuous barrier to prevent it entering the conditioned space.

GreeBo

https://www.boards.ie/discussion/comment/119977385#Comment_119977385

I'd argue that the point of doing it is to avoid draughty walls. You don't need to be air tight to avoid a draught.

The "best" approach very much depends on ones appetite and aptitude. If a good quality caulk + gun and an hour gives the OP 95% of what they want then that is the best solution for them, especially if removing all skirting with the associated making-do will only gets them 5% more.

MicktheMan

@GreeBo "You don't need to be air tight to avoid a draught."

Say what...

What do you think causes draughts?