Please help me figure out what is causing the damp

[PlummyPapa]

Hi,

I have recently moved into a new (very old) flat with me SO. The paint on the WC walls is bubbling and peeling and we have found there is a lot of moss on the exterior wall and watermarks on the window below. (Please see pictures) Could anyone please advice what to do and whether the damp walls in the WC is caused by an external leak by the soil pipe?

Thanks :)

Sorry, I can't seem to add any images but will try to describe the location. There is a soil pipe coming from the upstairs flat past our window that could be leaking. There is also a rain water gutter above that could be blocked and dripping down the wall... Not sure how to check? Or who I need to contact to figure this out...

Does sound like it could be penetrating damp.
First, go outside, when it’s raining hard, and have a good look what’s going on with the gutters.

On a dry day, when wall is looking dry, get owners of flatbabove to flush loo , several times, while you watch carefully what happens.

These should identify whether it’s the gutter- which my money would be on- or the pipe.

Just noticed you’ve written ‘walls’ plural- is that right?
Penetrating damp will only affect an external wall.
If it’s more than one wall, it might be condensation. Is the room cold?
Does it have an extractor fan?

Thanks your reply @Evidencebased, I think your idea regarding diagnosing the problem properly makes a lot of sense. There is such a mess of pipes it is hard to tell what the route of the issue is.

Also, yes it is on more than one internal wall, however it is predominately on the one external wall. Having said this, there is no extractor fan so it could also be condensation...

Hoping for some rain so we can investigate the gutter. The neighbours upstairs are away at the moment, so won't be able to check the SVP.

If you can afford it, hire an independent damp surveyor. I did this when buying a property and it was really useful. Cost me £250. He or she will diagnose it I advise how to rectify it. Don't use a damp proofing company who offer a 'free survey'. That's not the same thing.

You could use a trace and find company to find th root cause of the leak.
I've used one a couple of times and they were very good. Expensive though- cost was £520.
You may be able to claim it on your insurance though, or (depending on the location of the fault, from the upstairs flat or via the communal service charge.

If you've just recently moved in did your surveyor not pick this up? And if it's rented speak to the owner?

@AntiHop we ideally would like to identify the problem ourselves first. then if all else fails we were thinking about hiring a damp surveyor to come in and take a look as I've read stories about damp proofing companies over specifying which we don't want!

@Godowneasy i haven't heard of a trace and find company before. Do they just survey or do they rectify the problem in anyway? It seems a lot of money for a diagnosis.

@Bluntness100 We bought the flat and no it wasn't listed on the survey which is frustrating. But the survey was done in the summer and tbh we still would have gone ahead with the purchase. It would have been useful to know though!

I've taken a few photos which I have uploaded now.

No, they don't rectify the problem. but they spent two days (three man days) finding the source of the leak last time.

The pointing looks in a pretty poor state in your photos...

Agree with Godowneasy
The pointing/mortar looks to be missing from around the bricks this is a major source of water ingress.
Also it looks like you will need to replace the rotting wooden window with upvc window.
Only a small amount of water on that wall will cause problems over a long period of time due to being part rendered.

I think there is, or has been, a problem with that drainage pipe - the moss follows the pipe. It has caused water to get in behind any cracks in the mortar, it freezes, expands and the mortar is damaged and falls out which leaves it exposed to more water and damage, moss grows which holds water and plants get into the cracks and widen them causing further damage.
You need a solution that deals with all aspects or it will happen again. It is worth getting a decent local builder to have a look. He will know straight away. It is certainly penetrative damp and possibly condensation on the inside.

And some of the problem looks to be your neighbour's responsibility to deal with.