Damp external wall

[perizadah]

Hi all, hoping someone can help with an ongoing concern regarding one of the walls in my kitchen. It's a Victorian terrace with an old double storey extension (surveyor thought 70s) at the back of the house. No cavity wall and concrete floor in the extension. It's also north facing and not next to any other extensions so three of the four walls are open to the elements.

Shortly after moving in last summer we realised there was a leak under the kitchen sink which the vendors had wrapped jay cloths around but was slowly destroying the kitchen cabinet got in a plumber who sorted that pretty quickly.

Come the winter we realised there was no heating source and also had a lodger with a penchant for open-pan cooking without using the extractor fan, so we would come home to find water literally running down the walls in the kitchen, particularly the wall where the gas hob is which is the party wall along the boundary with the neighbours. Had a few words and things (mostly improved), and also installed a small radiator and did some draught proofing.

Now we've just had an electrician round who has looked at the kitchen and said most of the sockets are massively corroded because of damp in the wall and has replaced the sockets. When drilling into the wall, we got in about 1cm before noticing dirty water splashes around the hole (see pic below).

Does anyone have any clue why the wall is so wet? Could it be just from the moisture caused by cooking?!? There's no obvious smell of damp or any blown plaster on the wall but obviously a bit worried that there seems to be so much water inside!

Kitchens contain taps, hence water pipes. So much water might be a leak. Have you got a water meter?

Stand back and take wider pics of the wall to show height of damp. Include something to show scale.

Look at the outside for leaking gutters or pipes. Look for a dpc in the wall. How high is it?

Thanks for the response @PigletJohn . I'm working away at the moment but will try to answer as best I can.

No water meter (water co deemed not suitable), the taps are on the opposite wall and I assume the pipes are within the concrete floor.

There are actually no signs of damp unless you go 'into' the wall - i.e. drilling or looking at socket backboxes. Wall is dry to the touch, no blown plaster, skirting board seems fine. No smell of damp either. The affected socket was at worktop height so c. 1m above floor height and hole drilled was closer to 2m.The hole was drilled for a rawl plug so fairly small. If it wasn't for the electrician I'd have no clue there was an issue.

It's an inverted pitched roof with the higher side being the side where the wall is damp, so no guttering on that side. From the outside looking at the house there's an indent in the render about a foot or so above the ground level - don't know if this is the DPC? I'm not sure about what is on the neighbour's side of the wall though.

Does this help at all??

I see there is a bathroom above. There might be a leak getting into the wall, for example from a bath, shower or radiator pipe, and running down.

Also, have a look at the neighbour's side of the wall.

It's unusual for water to rise so far into a wall from a floor, although if the wall is made of lightweight concrete blocks, they are very absorbent.

Where is the boiler?

is the water black?

have you got a magnet?

water from radiator leaks is often black and contains fine particles of iron oxide that will stick to a clean magnet.

Okay attached pictures of kitchen and bathroom. The hole drilled in the wall was right by the internal door (above the towel rail you can just see the corner of) and all the sockets along that right hand wall were replaced due to corrosion, with the furthest one being right in the corner on the other side of the hob.

There's the heated towel rail on that wall above but not sure if it would have spread damp right across the wall. The boiler is just before the bathroom door, on the left so not next to the damp wall.

I have a feeling we'll need to get someone in to look at it but I've heard some horror stories about damp 'experts' so any advice much appreciated!

The water from the drill hole was black but thought that was just the drill dust - can check when I go back. The electrician didn't mention anything about the damp in the wall being dark though, would it have been obvious?

old breeze blocks make black dust, they have not been used for something like 50 years though (modern lightweight foamed concrete makes grey or white dust)

the water is high up and there is plenty of it, so I'd start with a plumber, then if necessary a roofer. Unless you have cracked rendering on the flank wall, I doubt it is rain.

Avoid anybody who sells such "damp-proofing" treatments as chemical injections, tanking, or magic plaster. You need to find the source of the water and repair it, not hide it.

Okay sounds like a plumber is first port of call - thank you!

If this is on the exterior wall Check whether there are ventilation bricks (you should be able to see them from outside - bricks with holes in them about 4" from the floor) Concrete floors need a damp proof membrane under them and vent bricks or you will get rising damp

If you had cavity wall I would check the guttering/roof for leaks. If there's a leak it can permeate the walls (if you drilled a hole in the wall in the floor above you would also find damp).

Leak easy to get fixed but no idea how they would fix the rising damp without redoing the floor so fingers crossed for a leak