Rising damp in cob wall

[CroxyP]

Hello
I have a cob wall inside the property between lounge and kitchen which was once the external wall. The farmhouse was built in 1670 so no damp course etc. On the lounge side we covered over some ugly exposed brick work with standard plaster and soon after the paint blistered, and despite several attempts with various Zinsser products it just kept failing. This reaches 1.2m from floor.
So can people here sense check my solution.
1. I have stripped the wall of plaster and back to bare stone. It was quite damp in places.
2. I have a heater blasting at it to dry it and a dehumidifier running constantly (incidentally, on the morning of the removal of plaster, the reading was 68% and by the evening it was 38%!!)
3. I plan to batten and put wood panels in keeping with other parts of the house, and install a long vent across the bottom to allow moisture to escape. The panels will have a moisture barrier to prevent rotting the wood

Thoughts would be great.
CroxyP

 

[montyjohn]

Rather than trying to stop the water escaping why not plaster it with some lime which can breath.
Use only breathable paints like limewash.
Don't go anywhere near it with things like zinsser.

It should then naturally regulate its moisture content.
Make sure the room has enough ventilation to handle it.

In theory a vented void would work. But it's a bit of a clumsy solution to a problem solved a long time ago.

 

[a twig]

Vented panels can work well and makes sense if you want the walls in keeping with the rest of your property - you just ideally need to vent the top as well as the bottom so you get the airflow.

 

[a twig]

There’s a few threads on here - a quick search on wainscoting should bring up some pertinent info

 

[phillc]

I'm struggling to visualise this - is it stone or brick or cob? I'm assuming it's something like stone to the ground floor, cob to the upper floor(s) and with various later brick repairs (blocked in doors, patching of the cob)?

If it's an internal wall I think I'd want to understand why it is getting so damp. Do you have concrete floors with DPM under, driving moisture up the walls? Or do you have a leak in your pipework somewhere ..? Or ..?

We're cob, built around 1720. We're at the bottom of a hill in a very wet part of Devon. Our internal walls are dry ...

 

[Cubist]

I'm just as puzzled as @phillc and for the same reason. Was cob used as a 'binding; material for the stones in some/all of this wall? Also, just how massive/thick is it?

 

[CroxyP]

 

[CroxyP]

The wall is 2 feet thick. I think it’s unlikely there’s any dpc as slate floor is very old and uneven. I’m at the bottom of a hill with drains possibly going under the house. Without digging everything up it’s impossible to access drains with a camera as it’s a u-bend design. The house is dry everywhere else. I suspect the damp may have come from a leak in the chimney on the other side which was due to flashing failure which would have dripped down a decommissioned Aga. That’s speculative. No leaks above. Roof flashing fixed and Aga recommissioned.