Sealing gap between windows

[Jblakes]

Morning all,

Onto the next issue (temp fix before we get new windows), we have two windows in main bedroom that are very drafty, not the actual glass but the fact some moron fitted them and I can see day light. Either way when I come sort it, I found the plaster board dabbed and dotted onto the widow insert (not sure what it's called) and I could feel cold air. So knocking it off. I found this.

This is a 25 old extension onto our limestone cottage. As you can see the outside walls are limestone, and breeze blocks inside. It's looks like a damp proof sheet has been inserted vertically with what I assume is loft insulation on the inner side of it, the issue is the limestone brick is damp to touch. It's also looks like a right mess and bodge city.

Can somebody suggest what to do? I was thinking filling the gaps with some lime mortar and lime plastering over, it won't be a brilliant fix but should stop the air leaks and also help reduce the moisture on the bricks, then seal outside with lime mortar, although the limestone bricks looks like they are stuck together with concrete?

Any help would be most appreciated, as another can of worms opened

Kind regards
James

 

[Cubist]

Hi J,
Best to start from the outside and deal with the interior afterwards. I would recommend that you use caulking cotton twisted and pressed/hammered firmly into the gap between the window frame and the external stonework and leaving a channel of approx 0.5-1cm deep. This will form a firm 'bed' for a lime mortar filler, or other sealant to close and finish the gap. Internally, and here I would defer to others, but I would be cautious about 'bridging' the external stone skin and the block-work, but you could use the same technique and materials to close the gap between the window frame and the exterior stonework before finally closing the whole thing up with some plasterboard and skim plaster.

Hope this helps.
Cheers,
Cubist

 

[paulc]

Had similar looking gaps around my front door and window. I used expanding foam to fill the gaps and then reattached timber (1/2" boards, 8" wide) around the reveals. Yes, a bit of a bodge, but it has killed the draughts.

 

[Jblakes]

Should I really be bothered about bridging if I use lime mortar? It's only to cover the gap up to stop cold air coming into the room.

Regards
James

 

[mardinor]

This is one application where I see nothing wrong with careful use of expanding foam

 

[Cubist]

An afterthought - when you've closed the exterior gaps it may be wise to check for excessive draughts coming from the cavity 'between' the stone and block-work skins. Nowt wrong in my view re judicious use of expanding foam.

 

[malcolm]

The inner and outer walls appear to have some sort of waterproofing membrane between them. The edge treatment is poorly thought out. I was going to react to seeing a mention of expanding foam on here but it probably is a fair bodge to terminate the already waterproof membrane.

Don't ever use it against wood. It's waterproof and the wood will rot away.

 

[Jblakes]

So just shove expanding foam both size of the membrane and cover the gaps. Should I care it the foam from both size touch ie bridge the gap?

And yes looks utter bull crap, must had been the same builder whos done all the other crap in the house

 

[malcolm]

Waterproof stuff like expanding foam can bridge the gap and the membrane will still work as intended. What was intended might cause issues in an older building that would otherwise like to be breathable but if it's an extension made the modern way you should be good.

 

[Jblakes]

Cheers, yes it's the modern cowboy way, by the look of it.

What would you put over the expandable foam? I wanted to just put plaster, ideally lime as I've loads left.

That going to cause an issue?

 

[malcolm]

Plaster won't work on expanding foam. You would need plasterboard or woodwool board as a base. Lime would work on either.

 

[Jblakes]

Got some spare wood wool too, problem solved . Cheers everybody

I'm sure I'll be back with the next issue.