Damp plaster at corner of window

[Patriq]

Hi all,
Looking for advice on this, unearthed whilst redecorating a 60s-built house I just bought. The new skim has never full gone bright pink in the corner next to one of the uPVC windows. You can just about dry it out, but then when it rains etc... back it comes.
I've attached a picture of this phenomenon.

During my investigations (prodding around), I found a gap in the outside sealant where the sill juts out over the outer bricks. Picture 2 below.

So, the hole is a good lead. But could it be anything else?
And what do I do - should I squirt expanding foam in as far as I can push the straw down the hole and then seal it up with silicone from outside? Never done anything like this, so advice much appreciated..
Thanks
Patrick

 

[foxhole]

Renew sealant to exterior.

 

[Patriq]

Thanks for that - on order. Also wondered if there was any additional problem as the darker bit in the picture has a hollow sound when knocked on as opposed to higher up (what I assume to be the cavity). Do you think just ensuring it is water-tight from the outside is enough, or does the suspected void need filling somehow?
Cheers

 

[Doggit]

You could try filling the void using a can of expanding foam, but if the supplied tubing is too big, then you won't get a straw down there to work, and would need to drill a hole wide enough, and is that worth it. As long as the outside is sealed properly, then I'd be inclined to leave the void alone.

 

[Gazman16]

Several possibility's but 90% of the time this indicates the pvc cills haven't been sealed at the ends before the windows were placed on top.
Usually happens when the window was fitted by a builder (no offense good builders!)
https://www.google.co.uk/imgres?img...WAhWkA8AKHWWjBeg4ZBAzCCsoKTAp&iact=mrc&uact=8


1st a question though. Did the window used to have trims around the inside that were removed and the gap plastered instead? If so DPC may have been beached by the plaster. Chop out a couple of inch squared in the damp patch's back to the brick/block to check.


If DPC has not been breached you are back to the 90% of the time scenario.
3 main options are:
1. remove and refit the window
2. remove a brick at each corner, Seal the ends and refit.
3. knock holes in the plaster corners to seal and patch up plaster.

Whichever one you go for check for crap in the cavity while its opened up.

 

[Patriq]

Sorry for what is probably a daft question but;

When we say PVC cills have/haven't been sealed... are we talking about a silicone seal, or something like that, having not been done when the plastic end piece is clipped on?
Thanks for the help with this.

 

[Gazman16]

As per the picture I put a link up for. The ends of the cill between the window and the pvc cill. Any water that blows up between the window and cill runs to the ends and into your walls

 

[Patriq]

Hi thanks for the help with this. I've explored more, pulled out the old sealant and found behind it that the sill is unsealed.
It's obviously hard to get at, but I'm thinking the gap is enough for me to have a go sealing it up without having to resort to ripping the window out etc. Any tips for this? Foam & sealant? Cheers

 

[foxhole]

The pvc strip on the inside at the bottom suggests the gap left after changing to pvc window was just covered, this would have gone up the sides and across the top.Looks like this pvc was removed at the sides before plastering , but still left a void behind. You could drill into the wet patch and if you hit the void you could pump in some foam. 10mm hole would allow foam tube through . You can feed it thru till you hit something then slowly draw out while foaming .

 

[Keithmac]

Hi all,
Looking for advice on this, unearthed whilst redecorating a 60s-built house I just bought. The new skim has never full gone bright pink in the corner next to one of the uPVC windows. You can just about dry it out, but then when it rains etc... back it comes.
I've attached a picture of this phenomenon.

During my investigations (prodding around), I found a gap in the outside sealant where the sill juts out over the outer bricks. Picture 2 below.

So, the hole is a good lead. But could it be anything else?
And what do I do - should I squirt expanding foam in as far as I can push the straw down the hole and then seal it up with silicone from outside? Never done anything like this, so advice much appreciated..
Thanks
Patrick

View attachment 128313 View attachment 128314

When I had my windows fitted last year I'm sure all the cills went into to outside course of bricks?, sealed all the way round the window and cill sides then mortar under the cill?.

 

[Gazman16]

You want to use LMN clear silicone (Low Modulus Neutral cure). You will need to clean the area as best as you can first.
You can get some adjustable angle silicone nozels that may help too.

I have marked the area on your pic that needs sealing

 

[DanP301219]

I have this exact problem with the plaster turning damp when there is heavy rain and we get a noticeable amount of draught too. Sounds silly quesiton, but which kind of tradesman would i need to come by to fix this? a reputable window fitter perhaps?

 

[Carlos8881]

I got same issue - did this become resolved?
fyi - our plasterer removed the window trims and exposed a gap - unsure what he did once he plastered upto the window.
slightly frustrating