Fairly new to lime plastering so bear with me.

About to start plastering most of the walls in our renovation. The house is mid-terrace, but it joins an older house where the roof is perpendicular to the roof of the terrace, so the ridge of our house hits the middle of their ridge, giving us two valleys (T shape in plan).

After heavy rain a section of our downstairs party wall becomes visibly damp. Not dripping, but darker than the surrounding stones which remain dry. I've been into the attic, and onto the roof, and can't see any signs of damp, or water ingress. Our neighbour also says his side is fine.

Aside from re-roofing the whole house, not really sure what to do..

So my question is; if I plaster over this part of the wall, which occasionally sweats, will the lime plaster fail?

Thanks in advance.

Hi Nick,

Yes downstairs, about a meter off the floor and half a meter from the ceiling. I'll try and get a photo tomorrow in the light.

The walls upstairs seem to be fine.

The rafters of the older stone house sit on a wall plate which sit halfway up the upstairs bedroom wall. At the moment i'm guessing there's water getting in somewhere down the valleys, which then makes its way down the back of the stone wall, and comes out at this seam.

Maybe need to get a roofer in to advise?

''What about putting a chemical damp proof into the masonry where it gets damp? Guessing it would just move the damp elsewhere?.''

Nooooo! Even if you believe they work, it's better to try to track down the source.

<blockquote><cite>Posted By: tony</cite>Can you drill three holes in the wall, collect the dust in a zip type bag and send it to me.

There is a possibility of hygroscopic salts on or near the surface of the stone or

Lime will sort it out but please use lime wash or breathable paint.</blockquote>


Certainly can tony. What's your address?