Another damp thread - "informal" party wall notice served

[CheeseBadger]

Anyone want to see my wet patch? I'll post photos after the explanation.

I just knocked on the neighbours' door to borrow their key to the alley behind the house due to a trapped dustbin. But I digress. They said they were meaning to call round because they're planning to have some damp treatment applied to our party wall. Very nice of them to tell me. For context we're a clay brick Victorian end terrace and they're our only connected neighbours. And now it gets weird.

They had a membrane tanking system with French drains applied to their cellar just over two years ago. Since around that time (I couldn't swear that it was exactly then) we've both had a mysterious wet patch in our front hallways. We noticed it first, but going from their description it seems more extensive on their side. They've now contacted the tanking contractors, and they're proposing a chemical injection DPC at ground level and replastering of the hallway on our neighbours' side.

I have numerous concerns about this, but the main one is that with a damp barrier at ground floor level and a plastic membrane against the party wall in the cellar, our cellar is now going to bear the brunt of any moisture which needs to diffuse out of the masonry. It'll have nowhere else to go. The cellar is unfinished bare brick on our side, and it feels fairly dry to the touch. This makes me even less convinced about the contractor's diagnosis of rising damp than I normally would be. And I'm someone who is aware that "rising damp" only exists in the UK in the minds of people who make money fixing it.

I like these neighbours. They're lovely people. They're just not very practical. I recently had to point out to them that their gutters were overflowing and soaking the front of our houses. It hadn't occurred to them that there shouldn't be a waterfall outside the front door.

Anyway, to the point. I think I'm going to need to pay for my own report on the source of this damp. I don't want to be the guy that just says "no" for reasons they can't understand. But they just looked at me a bit blankly when I mentioned that the dry cellar wall made "rising damp" unlikely. So does anyone know of a reliable builder / damp expert who doesn't buy into the whole DPC pantomime in the north west? South Manchester if it helps. Sorry also for the essay...

Images here. My wet patch ends around the start of the radiator. Theirs is apparently from the front door to the stairs.

I would suspect a leak from a pipe would be more likely.

I'm racking my brains to think who you could contact - we're not far away and I used to work for a property management company so had lots of contacts. Does the water supply come into your houses near the front door and are there stopcocks either in the front gardens or the pavement outside? Does either house have a water meter? You could test for a leak by seeing if the water meter is still going round when no water is being used.

there's a lot of water.

it's abnormal to have water rising from the ground to such height when there is a cellar. Even if the other side is tanked it should be able to evaporate out of your side.

show us some pics of your cellar wall. how is your cellar ventilated?

I agree a pipe leak is more likely. Are the floors boarded, or is there an impervious covering?

p.s.

the wet mark looks higher at the right hand side and the floor also looks dark. Please show us more pics over there.

Meanwhile, draw round the tidemark with chalk or a pencil so you can see how it changes over time, for example after rain or on bathnight.

"their gutters were overflowing and soaking the front of our houses. It hadn't occurred to them that there shouldn't be a waterfall outside the front door."

"we've both had a mysterious wet patch in our front hallways."

"My wet patch ends around the start of the radiator. Theirs is apparently from the front door to the stairs."

I am coming to the opinion that this is rainwater lying on the hall floor and soaking into the wall. Is the hall floor by any chance solid, with a tiled or terrazzo finish? Or is there a covering such as laminate or vinyl that water could lie beneath?

We have had a lot of very heavy rain recently too. Is there a join in the roofs of your two houses along that party wall line? In a house we used to live there was sometimes a damp patch low on an internal wall - it was directly under loose flashing.

Sorry for the late response. I've been at MRI all morning having been knocked off my bike on the way to work. But that's another story...

No join in the roof near that point. I thought it was a leak in the canopy at the front of the house (there's a 3 foot pitched slate roof over the ground floor bay which continues over the front doors). I got the roofer in to sort that out because there was a smaller wet patch on the other side of the front door as well. I thought water was getting in through that roof and running round the badly fitted front door frame. It cleared up after that, and is now dry on the other side of the door, but this side seems to be getting worse again. They cleared the gutter in the caopy roof about 6 months ago, - that was soaking the front wall. But that hasn't completely fixed it.

Hall floor is suspended timber on both sides with original sanded pine boards. It doesn't feel unduly wet.

The wet patch is higher on the right hand side of the pictures near the door. That's what makes me think it's penetrating damp. I can't get into their cellar to inspect their plumbing, but there are no obvious leaks on our side.

No water meter. That would have been the first thing I did.

Is there a soakaway or drain in the area and is the canopy original to the houses? Will your neighbours let you look around their front door and see if you can see what's going on?

Just a thought - has the contractor they had to do the work actually been back to have a look do you know?

No soakaway. The canopy roof is original, and should keep the front of the houses dry at ground level. I can see their front door fine - it's a foot away from mine.

It is the original damp proofing contractor who did their cellar that's proposing this new DPC.

perhaps he needs a new van, and knows a soft touch.

I know, right? Which is why I need to find one who doesn't sell DPCs to help me correctly diagnose the problem. Any ideas welcome...

OP - I'd use the RICS website search function to find a surveyor in the area who specialises in damp. Once you have some details you can look for reviews, etc online and take it from there.