Damp in party wall - please help!

[Blueberry72]

Thank you in advance for any help.

We bought a 1906 terraced house last year. There was a small amount of damp but the property had been empty for quite a while so we assumed it would dry out. Over the the winter, we used a dehumidifier and had the heating on and the walls dried out completely.

Over the last couple of months, the damp has returned.

I mentioned it in passing to my neighbour and she said she has terrible rising damp. She has contacted her landlord who have sent me a formal letter (they are also solicitors) instructing me to contact my home insurers because our property is making their property damp.

They are blaming our floor. Many years ago, the wooden floor was replace by a concrete floor and they are alleging that a membrane wasn't put down as it should have been. This was two or three owners back so we have no record of it.

For us, the damp is only around a chimney and doesn't spread to the other walls. Is it likely that our small amount of damp is causing widespread damp next door?

I'm really worried that it will cost a lot of money. I'm on maternity leave and have a small baby so we don't have money to spare to take up floors and damp proof two houses.

Can anyone give any advice as to what we should do next?

 

[JohnD]

have you got a water meter? Has your neighbour?

 

[Blueberry72]

Thank you for your reply.

Yes, we have got a water meter. As far as I'm aware, the whole street has as the local water company installed them all over about 5 years ago.

 

[chris1982]

Damp around old chimney breasts is often due to hygroscopic salts, which migrated from burning coal into the bricks and the plaster, drawing moisture from the air.

 

[JohnD]

turn off all your taps. Take a torch and look at the water meter. Wipe the glass. In the middle is a bubble of air. It turns all the time water is passing. Is it moving?

Is your neighbour's?

Post several photos of the damp, close and distant. Include the whole wall. Show us the air vent that ventilates the chimney.

 

[Blueberry72]

I will have a look when my husband gets home. My neighbour is now on holiday but I'll ask when she gets back.

 

[Blueberry72]

Damp around old chimney breasts is often due to hygroscopic salts, which migrated from burning coal into the bricks and the plaster, drawing moisture from the air.

Please could you elaborate? The chimney now houses a gas fire (which we don't use) and the room had been replastered. Would this still be an issue?

 

[JohnD]

My neighbour is now on holiday

that's a good time to look at her meter as she will presumably have turned all the taps off. I'd write down the meter reading as well. Do yours first so you learn how.

It is very common for the water pipes in and under old houses to be leaking.

taking out a (rotten) wooden floor and filling in with concrete is sometimes done when damp is bad. No particular reason to go to all that trouble and expense normally.

 

[chappers]

Please could you elaborate? The chimney now houses a gas fire (which we don't use) and the room had been replastered. Would this still be an issue?

could be yes. Also bear in mind the two issues could be totally unrelated.
As for the neighbours next door I would await any action from them first.

 

[Blueberry72]

View media item 100282View media item 100283View media item 100284
I've added descriptions to the photos. All other internal walls including the rest of the part wall (and other party wall) are dry

 

[chris1982]

Please could you elaborate? The chimney now houses a gas fire (which we don't use) and the room had been replastered. Would this still be an issue?

We had a problem like this in a previous house. It rained down the chimney, soot got washed into the plaster and left behind salts that attracted further moisture. To combat this, we capped the chimney, took off the plaster, applied SBR slurry, followed by renovating plaster (non-gypsum based).

 

[JohnD]

it's quite low, but there's a tremendous amount of it.

I stand by my suspicions of a water leak.

It could be under your house or the neighbour

Stand back a take a wider photo of the whole wall.

Where the watermark is highest might be nearest the source.

draw a sketch of the houses, and where the water-meters/outside stopcocks are, and where the internal stopcock is (or where the kitchen sink used to be when the house was built). Also position of radiator pipes just in case.

"behind skirting" is that an old water pipe? Is it cold? Show us where it comes from.

Sometimes old pipes are behind a fire where there used to be a back-boiler and still may be connected. They are likely to be fed from a small tank in the loft.