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Damp Patch under Window Cill and External Efflorescence after Repointing

Postby mthurman » Wed Jan 20, 2016 10:19 am


This is my first post on here after reading a lot of useful stuff on these forums.

Since moving in to our house (a 1890s back to back knocked through) we've had a few issues with damp which we've had to ignore for a couple of years due to not having the funds to do anything about it! Now I'm trying to tackle it.

It's mostly on one side of the house where we have damp patches coming up from the skirting board and a big damp patch under one window cill.

I had a few people round to look at it - some said rising damp, others said it was due to our failed pointing on the wall. The wall did desperately need repointing (bits falling out, bits completely missing) so I thought it would be best to have that done first before hacking off any plaster etc.

We've recently had the whole wall repointed and they externally injected a damp proof cream (?) whilst they were at it. They seem to have done a good job and have used lime and not concrete.

Obviously I know that damp can take a long time to dry out, but I'm just wondering what people think to the photos I've uploaded with this post and what solutions you might suggest.

A few things I'm wondering...

1) The wall was filled with cavity wall insulation about 10 years ago (before we moved in to the property) - could this be causing damp issues?

2) The damp patches fade if I point a fan heater at them for a while but then slowly reappear (one photo shows the faded patches)

3) I'm borrowing a dehumidifier as I've read that this might help remove the damp patches - if so, what's the best process here? Will it help draw moisture from the wall? Do I make it so that the dry air is hitting the wall or do I make it so that the air is being drawn in from the wall?

4) Could water be getting in elsewhere to cause the damp under the cill? The window appears to be sealed so I don't see where it's getting in.

5) Since we've had the repointing done, we're getting a lot of salting/efflorescence externally (see image attached). I'm brushing it off every day, but wondering what it means? Is this a good sign of the wall drying itself out with moisture escaping, or does it indicate a different issue?

Sorry for all the questions, but after hours of searching I can't find any help.

Thanks in advance.
Salting on external wall after repointing - appears every day
External view of the window after repointing
After drying out a bit with a fan heater, but it always comes back after a few days
The damp patch under the window cill
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