Damp wall, remove plaster to dry?

[endecotp]

Dear Experts,

Photo shows an alcove in my living room where there has been water ingress over quite a long period due to gutter problems. That has now been resolved and I need to make good inside.

This is a very old building, converted to its current layout in about 1980. I believe that at that time all of this was hidden behind plasterboard on studwork, but some previous owner decided to remove that to expose the old stonework. So the surface you can see is emulsion paint over plaster (of various ages) over old stone - except where it’s probably over brick filling an old window opening.

My plan is eventually to reinstate plasterboard, with insulation. I’ve been doing this progressively around the flat. So the appearance doesn’t matter.

I have just removed the cupboard that was filling the bottom half of the space.

Question is, what do I need to do now with this wall? Do I need to hack off the plaster to expose the stone, to encourage drying out?

Generally it does not feel damp - with one small exception, to the left of the gas pipe. I have wire-brushed most of it, which has removed the efflorescence and some of the paint. It’s much worse on the right than in the middle, which is where there is probably brick.

What do you think?

 

[Wayners]

Very old building as in no cavity walls and lime plaster used?

 

[endecotp]

Very old building as in 1643. But quite how old any particular bit of stone etc. is, is hard to tell. I think some of the plaster is circa 1840 when I know the original wood panelling was removed. One thing I don’t know is when this window was blocked - or even if it was at some point a doorway!

 

[foxhole]

How long since water ingress problem cured? Can take many months ( even a year or more)for wall to dry and salts to stop leaching out.

 

[endecotp]

How long since water ingress problem cured?

Almost a year now I think.

 

[^woody^]

The plaster needs to come off anyway because of hygroscopic salts. Hire a drier and put it in that alcove.

 

[endecotp]

The plaster needs to come off anyway because of hygroscopic salts. Hire a drier and put it in that alcove.

Hi Woody,

Can you elaborate on that a bit? Why do I care about the salts, if they will be hidden behind plasterboard? Are they damaging the wall in some dangerous way?

Thanks.

 

[foxhole]

Does gas feed thru from exterior, may be letting water in.

 

[endecotp]

Does gas feed thru from exterior, may be letting water in.

Well maybe a little bit, but no; we understand and have fixed the source of the water, which is from much higher up.

 

[^woody^]

Salts will absorb moisture and this in turn could promote mould growth within any void, or create a cold spot on the inner face which will do likewise.

Salts should be neutralised before you proceed

 

[endecotp]

Salts will absorb moisture and this in turn could promote mould growth within any void, or create a cold spot on the inner face which will do likewise.

Thanks. I need to have a closer look at what I actually have. I think much of the white powdery stuff is loose plaster rather than salts. I’ll see if I can get some good close-up photos.

 

[^woody^]

There will be hygroscopic salts in plaster that has got wet, you wont see them. The white powder on the surface are the crystallised deposits - efflorescence