Expanding Foam in Cavity Wall Issue

Joined
9 Nov 2020
Messages
8
Reaction score
1
Country
United Kingdom
I am a landlord and my tenants experienced issues with damp on the inside of a bay window and it didn't seem like there was an issue with condensation or ventilation (as is usually the case). I noticed a crack where the bay window render meets the brickwork on the outside of the house and thought it may be causing the issue.

I thought I would fill the gap with an all-weather sealant in case this was the cause of the damp. The gap at the top (just above where the arrow is pointing) was fairly big (around 0.5-1cm) so I thought I would use some expanding foam first. Now, what I didn't realise was that the gap was essentially leading straight to the wall cavity so all of the foam just fell down (750ml can). I only then realised it may have actually been a big (and very silly) mistake which could potentially lead to more issues.

I wanted to know if this is something I should worry about and whether there is anything I should do now before I experience any issues with that?
 

Attachments

  • 66839fd2-ffa9-4183-b049-b0d04c9d47b4_LI.jpg
    66839fd2-ffa9-4183-b049-b0d04c9d47b4_LI.jpg
    493 KB · Views: 230
Joined
28 Jun 2005
Messages
21,523
Reaction score
1,963
Country
United Kingdom
so I thought I would use some expanding foam first. Now, what I didn't realise was that the gap was essentially leading straight to the wall cavity so all of the foam just fell down (750ml can).
into the cavity ? No worries loads of houses have foam filled cavities
 
Sponsored Links
Joined
9 Nov 2020
Messages
8
Reaction score
1
Country
United Kingdom
Yes, or at least that's the only way I can explain it swallowing all of the foam. My thinking was that it could end up creating a 'connector' between the outside wall and the inside one, ultimately leading to more damp
 
Joined
3 Sep 2006
Messages
35,954
Reaction score
4,984
Location
West Mids
Country
United Kingdom
You'll have to wait and see. It's the wrong foam for cavity fill

Cavity foam injection is a different foam, with different properties, expansion and cell formation (not hollow like this canned stuff)
You should have just pointed the gap up with mortar or a mastic
 
Sponsored Links
Joined
16 Oct 2020
Messages
260
Reaction score
48
Country
United Kingdom
Your bay DPC is being bridged.
The bay render is in ground contact, and moisture is being pulled up the wall by capillary attraction - the dark smudges you can see at the base of the render are signs of damp.
You have a suspended floor, and its possible that the joist tails supported in the bay and along that frontage are being affected by penetrating damp.

Why not cut back the bay render 50mm above ground level, and post pics of the damp inside the house?
 
Top