Mysterious damp / water leak

[Patrick_]

Hi,

I'm currently renovating my flat and run into a damp problem. I don't really know what to do. Any suggestions are welcome..!

My contractor found a damp area on the wall and suspected some water leak from the flat above. In that area of the flat above is their boiler, and they indeed carried out some boiler work recently. However, the owner of the flat above arranged some contractor to check that area and the boiler, and found nothing. That was in July.

Then they suggested it's due to some one-off water spill when they carried out works on the boiler and nothing to worry about. My contractor didn't challenge that and continued the renovation work.

Now, a few weeks have passed and we have plastered the wall and begun painting. The damp didn't seem to disappear or shrink in size. My contractor told me it is extremely likely there is leak from flat above. However, the owner of the flat above and his contractor still say they see nothing wrong in his flat. They say everything above their floor level is dry, and 'the cold mains supply is also dry', etc.

I'm not sure what is the best way forward. I have attached some photos taken in the past few months and circled the area in red. Any suggestions are welcome!

thanks
Patrick

 

[CBW]

There could be a concealed leak, for example; if the boiler condensate pipe runs behind kitchen units. Also is the other side the wall external? If so, you might want to check that out too.

 

[Madrab]

They say everything above their floor level is dry

Invariably if it's dry above then it could be under their floor??

You could have investigated when your ceiling was exposed before you dropped it. You could then have seen if it was pipework under the floor that's causing it. Now the ceiling's up then it would be difficult to investigate without lifting the upstairs floor. They seem reluctant to do that?

Do you have a factor?

 

[Laurieo]

Have you checked your wall for hidden pipes ,could be a lead pipe buried in wall with a pin hole leak .

 

[Patrick_]

Thank you all for your suggestions.

Also is the other side the wall external? No. The building is a terraced house. The wall with the damp patch is a party wall.

You could have investigated when your ceiling was exposed before you dropped it.
-> I agree! The thing is the problem didn't occur before the dropped ceiling installation. Now I'm not sure what to do.

I checked some websites. It seems there are some professional leak detection service who uses thermal imaging or other technologies to detect leak. I received a quotation of 600 quids for a check (central London)... Should I use such service? or I ask my contractor to create an opening again...?

 

[polesapart]

Thermal imaging is more appropriate to situations like pipes buried in concrete and is not guaranteed to work.

Eyeball Mk1 and dusty finger more reliable.

If the patch persists/grows bigger you'll need to create access either from above, if the neighbour will cooperate, or from below.