Insulating a single skin brick wall

[Timmyk86]

Hi all,

I need to insulate and plaster a single brick wall that is part of a stairwell up to a loft conversion. 50% of the wall has an unconverted loft on the other side, the other 50% is straight to the elements. Gets bloody cold in the winter. Size is 4.8m x 4.8m - pic attached.

How would you go about insulating and covering this? There isn’t much depth to play with before it starts impeding on the stairwell space and I want to be really sure that no moisture gets stuck in between the brick and the insulation. I don’t mind if it’s not amazingly well insulated - just has to be better than it is now.

Thinking either a small stud wall with insulation and plaster over that, or insulated plasterboard straight on to the bricks.

Thanks for any advice!

T

 

[Wayners]

Watch Charliediy on YouTube as he covers this

 

[Wayners]

Oh. You can also look at sprayed cork which can be applied directly to single skin brick walls for insulation.

 

[Timmyk86]

Oh. You can also look at sprayed cork which can be applied directly to single skin brick walls for insulation.

Thanks. Is that the one with the SWIP insulation? Looks pretty good but I think the minimum is 65mm thick + plasterboard so really encroaching into that stairwell space. In terms of insulation I need it to be better but it doesn’t have to be amazing. Main concerns are avoiding condensation and mould and ease of installation.

Any experience of the spray cork? Is it any good?

 

[Deluks]

Cork slabs direct to wall would be more cost effective and could look quite nice.

30mm SecilVit Cork Board | Insulation Merchant

SecilVit Cork Board insulation is made entirely from natural and renewable cork. Providing natural and sustainable insulation. Cork is a breathable material.

insulationmerchant.com

Aerogel sheets if you want the posh option. ££££
Otherwise screw insulated plasterboard straight on, at a thickness you can bear, without losing space.

 

[Timmyk86]

Cork slabs direct to wall would be more cost effective and could look quite nice.

30mm SecilVit Cork Board | Insulation Merchant

SecilVit Cork Board insulation is made entirely from natural and renewable cork. Providing natural and sustainable insulation. Cork is a breathable material.

insulationmerchant.com

Aerogel sheets if you want the posh option. ££££
Otherwise screw insulated plasterboard straight on, at a thickness you can bear, without losing space.

Thanks. Would the brick need to be waterproofed before fixing cork boards? And can plasterboard then be fixed to the cork?

I was thinking insulated plasterboard may be the easiest option, but was worried about possible damp behind between the brick and the insulation if I did that. Breathable membrane between perhaps?

 

[Deluks]

The cork can be left bare. And it's breathable.

The insulated plasterboard should be foamed around the perimeter.

 

[endecotp]

I was thinking insulated plasterboard may be the easiest option, but was worried about possible damp behind between the brick and the insulation if I did that. Breathable membrane between perhaps?

Areyou imagining dampness coming from the outside through the brick, or from moist air inside that condenses?

 

[Timmyk86]

Areyou imagining dampness coming from the outside through the brick, or from moist air inside that condenses?

Well, either really.
As it’s just a single brick thick I can imagine water can wick through the wall. I didn’t want it getting trapped behind any insulation I put in.
Likewise I suppose warm air could hit that wall fun the inside and condense on it if there are any breaks in the insulation.
Just not sure how to manage it!

 

[Deluks]

Is it literally a single layer of brick or a solid wall made up of two leaves of bricks?

If the first one, yes it will be susceptible to water ingress, but only under certain conditions, have you had any issues with this?
One would wonder how that conversion got past building regs.

Rendering or sealing the outside wall would help.

 

[NorthWest1]

Check out DIY Charlie on YT, he has a couple of posts about insulating a solid wall, its an absolute minefield. In one, he comes back months after fitting insulated plasterboard and looks behind the cavity.....soaking wet. Even the government documents ive read regarding solid wall insulation ( internal ) are full of ifs, but & caveats. I don't think there is a 100% safe solution.

 

[endecotp]

As it’s just a single brick thick I can imagine water can wick through the wall. I didn’t want it getting trapped behind any insulation I put in.

You’re not currently seeing any signs of damp, right? I think the important thing is to keep the outside in good condition, i.e. maintain the guttering, re-point if necessary, maintain any render etc.

Likewise I suppose warm air could hit that wall fun the inside and condense on it if there are any breaks in the insulation.

Sealing the foil-faced insulation boards with foil tape is supposed to address this. It looks like it’s a large single area without holes for electricals or other complications, so you should be able to do this efficiently. BTW people generally prefer putting up insulation boards and then plasterboard over the top separately, rather than using insulated plasterboard.

 

[NorthWest1]

Sorry, someone had already mentioned DIY Charlie.

From what I understand, once the dew point has been moved to the void between the plasterboard and the wall, there are two ways of combating the moisture effects; either try and seal it up or vent it. Sealing it up to the point where no warm vapour can get in from the inside seems difficult to me and then there's moisture coming through the brick from the outside as well. I did read a couplue of articles about venting the void, just like a cavity wall, however, it doesn't seem to get much discussion now.

 

[Harry Bloomfield]

I need to insulate and plaster a single brick wall

The brick pattern, suggest that is a double brick wall, with no cavity.

 

[endecotp]

Sealing it up to the point where no warm vapour can get in from the inside seems difficult to me

As I said above, in this particular case it looks about as easy as it gets.