Damp in centre of house

[RModus]

I bought a mid terrace Victorian house about a year ago. It seems the previous owners indulged themselves in a significant amount of bodge work.

An area in the center of the house has been showing damp since I moved, which has progressively got worse (images attached). The damp appears to track mainly along corners, beading and dado rails, only starting from about 1m from the floor. I removed one of the recently installed light switches as it was starting to rust and tested the brickwork behind with a damp meter, which showed it as damp.

Both damp walls are supporting the stairs in the center of the house and there is a damp musty smell under the stairs. There is very little sub-floor ventilation as the brickwork is sat directly on the soil below. Strangely, it looks like half of one of the walls has a DPC (possibly a result of repair works to the wall when the bottom couple of stairs were replaced).

I have removed a couple of floor boards from upstairs directly above to check for any leaking pipes and everything seemed dry.

Is it possible that the damp could be rising up the brickwork, then exposing itself where it can find a gap in the render (like the light switch)?

I had a damp specialist in who recommended re-rendering and plastering, which I didn't think would fix the root cause of the problem. Any advise would be much appreciated.

 

[blup]

The plan doesn't seem to match the pics e.g the underside of the stairs in pic 2 are adjacent to an external window but are shown on the plan as perpendicular to the hall.

It could be rising from the stair walls through the plaster, so worth getting an expert view on a dpc install and breathable i.e. non cementitious plaster.

Blup

 

[RandomGrinch]

Hi,

I am definitely no expert, and I'm afraid I can't add much to help!
I have dealt with damp issues on my own Victorian mid-terrace.
My issues were mostly down to inappropriate use of materials (cement render and gypsum plaster) and were solved by adding ventilation and stripping back the hard materials, adding breathability.

However, your issue in the middle of the house seems odd!
Many will say rising damp is a myth! I won't go quite that far, but damp rising that far up is almost impossible, due to the mass of the water overcoming the forces of capillary action.
I would suspect the issue was due to a leak somewhere (are the upstairs walls damp?).
Even if the leak had been fixed, the walls may still need time to dry out.

...also, damp meters can not always be trusted! The salts that evaporate off the surface of damp plaster will cause a huge change in the resistance measured by a standard damp meter.

There are other diagnostic tests that can be carried out by independent experts, that will help find the source of the dampness.
I'm afraid you need an expert who understands Victorian properties, and doesn't want to sell you a cure!

Good luck!

 

[MrsRenovator]

We had a flood 20 years ago from a frozen attic pipe. The water didn't spread evenly. It gathered on ceilings and then came down various different walls. The metal plastering corners are still rusty under my paint seal. And removing light switches reveals the rusty back boxes.

Could yours be historic flood damage?

 

[JohnD]

Is this on the ground floor or upstairs?

Is there a chimney or fireplace nearby?

How many water tanks are in the loft? Are they full?

Have you got a water-meter?

Show us some pictures of the roof, and the air-bricks

Do not allow anyone who sells silicone injections into your home.