Expanding Foam into Cavity Wall Mistake

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damyan24

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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 this?
 

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  • Expanding Foam into Cavity Wall Mistake
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Mate sell your house and run for the hills.youve just created a s**t storm,the foam is literally guna eat your house..run and don't look back
 
Kinkyboy said:
Mate sell your house and run for the hills.youve just created a s**t storm,the foam is literally guna eat your house..run and don't look back
Click to expand...
Hi, my concern is that the foam may 'bridge' the cavity and allow damp to migrate from the outside in. And yes - I may be overly worried about it :)
 
damyan24 said:
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 this?
Click to expand...
You fired a whole 750ml can of expanding foam in to fill a small crack?
 
damyan24 said:
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 this?
Click to expand...
It’ll be fine mate don’t worry!
At least you didn’t end up like Casper here when he tried sticking a ceiling rose up with it.
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Don’t worry about it
Foam is not particularly a good conduit for damp
Are there trickle vents on the windows and are the tenants keeping them open?
 
"the gap was essentially leading straight to the wall cavity" Well it shouldn't, the bay brickwork should continue and key into the wall brickwork, and gaps mortared. You didn't say where the damp was but if you found that gap I'm guessing the damp was on the other side of it.
With a bit of luck the foam has just closed the air gap inside 'twixt bay and wall, and yes, maybe bridged the cavity but ignore that. Suggest you now fill the gap with mastic in either a matching colour or a full-on contrast like black. Check the other side because it's likely to be the same, and the airbricks as Carl & Andy suggest
 
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