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Cold air inside the cavity wall


JJ452

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I've recently moved into the a new home during the summer and now as the temperatures are dropping I'm beginning to find the problems...

 

The house was build in 2011 and is brick exterior (cement rendering) and brick interior walls with concrete slab floors. As far as I can tell it has polystyrene beads in the cavity wall (visible in the loft) and has 300mm loft insulation. I have noticed a number of issues which I have mostly addressed already -

 

Window trickle vents leaking significant air
Kitchen extractor fan ducting not properly sealed
Poor door seals

Loft hatch not insulated or sealing well 

 

The house now seems to hold heat reasonably as last night the minimum outside temperature was 6 degrees and over a 10 hour period from 11pm to 9am without any heating the open plan kitchen/dinning room dropped 1 degree (19 -> 18), hall dropped 0.5 degrees (19 -> 18.5) and living room 1 degree (22-> 21). 

 

One thing I can't figure out however is the cold air coming from the electrical sockets. Every single socket which is on a wall facing the exterior of the house is letting in quite a noticeable draft even when it's not what I would call windy outside - but not the sockets for interior walls. I confirmed this by checking the location we removed a sky cable which was drilled through the cavity wall and was sealed on the outside but not yet repaired on the inside and there was a significant amount of cold air coming from the cavity wall. 

 

 

Is this normal? I have read air needs to move within the cavity wall to prevent damp but surely it shouldn't be felt coming out of the sockets? If this is normal do I just seal around the socket with a fire putty pad? 

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Unfortunately it is all too 'normal' for modern houses, especially of the age of yours, before mandatory air testing was introduced. As said above, the walls will be dot and dabbed with plasterboard, and the air will infiltrate from outside. There is no requirement to ventilate this cavity, and doing so will only cause negative issues with regards to insulation and airtightness.

 

Theres not a great deal you can do to permanently fix this issue within taking all the plasterboard off and starting again. One thing you can do is go around the perimeter of the wall (corners, ceilings, and floors), drill holes every 10-15cm or so, and inject some FM330 type expanding foam, elastic, and this should cure some of the air leakage paths, and its wise to do around any penetrations in the wall also, such as sockets to stop air entering the room. Given doing this, it still won't be great but may help somewhat.

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27 minutes ago, crispy_wafer said:

Presuming those walls are dabbed plasterboard?

 

Had to check - it is wet plaster straight onto the block. I took one of the sockets off to see if the cabling was through the block in any way but appears to be going up into the suspended ceiling where I assume the cabling is routed. 

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2 hours ago, JJ452 said:

I've recently moved into the a new home during the summer and now as the temperatures are dropping I'm beginning to find the problems...

 

The house was build in 2011 and is brick exterior (cement rendering) and brick interior walls with concrete slab floors. As far as I can tell it has polystyrene beads in the cavity wall (visible in the loft) and has 300mm loft insulation. I have noticed a number of issues which I have mostly addressed already -

 

Window trickle vents leaking significant air
Kitchen extractor fan ducting not properly sealed
Poor door seals

Loft hatch not insulated or sealing well 

 

The house now seems to hold heat reasonably as last night the minimum outside temperature was 6 degrees and over a 10 hour period from 11pm to 9am without any heating the open plan kitchen/dinning room dropped 1 degree (19 -> 18), hall dropped 0.5 degrees (19 -> 18.5) and living room 1 degree (22-> 21). 

 

One thing I can't figure out however is the cold air coming from the electrical sockets. Every single socket which is on a wall facing the exterior of the house is letting in quite a noticeable draft even when it's not what I would call windy outside - but not the sockets for interior walls. I confirmed this by checking the location we removed a sky cable which was drilled through the cavity wall and was sealed on the outside but not yet repaired on the inside and there was a significant amount of cold air coming from the cavity wall. 

 

 

Is this normal? I have read air needs to move within the cavity wall to prevent damp but surely it shouldn't be felt coming out of the sockets? If this is normal do I just seal around the socket with a fire putty pad? 

They are not really for this purpose but will do a grand job of this, get some intumescent putty pads and fit them to the backboxes. That will seal them up and fire rate your sockets!

 

 

Edited by Carrerahill
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Great thanks, I'll seal the boxes. Should I be concerned about the air in the cavity wall where the sky cable was removed? I guess there isn't much I can do about this other than getting the insulation topped up? 

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3 hours ago, JJ452 said:

 

Had to check - it is wet plaster straight onto the block. I took one of the sockets off to see if the cabling was through the block in any way but appears to be going up into the suspended ceiling where I assume the cabling is routed. 

Are you absolutely sure and not just landed on a dab? I'd be very surprised that a 2011 property wasn't dotted and dabbed. Tap along the wall, it'll sound hollow if it is.

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37 minutes ago, MikeGrahamT21 said:

Are you absolutely sure and not just landed on a dab? I'd be very surprised that a 2011 property wasn't dotted and dabbed. Tap along the wall, it'll sound hollow if it is.

 

Certain - it's solid all round. I also looked into the hole where the sky cable was coming through and it's brick the whole way to the cavity wall. The property is a self-build by the previous owners so not a mass produced new build. 

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15 minutes ago, JJ452 said:

 

Certain - it's solid all round. I also looked into the hole where the sky cable was coming through and it's brick the whole way to the cavity wall. The property is a self-build by the previous owners so not a mass produced new build. 

Ahh fair enough, you've a good one there then!

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