Plaster sinking and breaking

neilmcl

Have you any radiator pipework running along the area?

CatLady87

Potentially. The radiator is in the far corner of the room (other side to the damp issue) but the floor is stone so not easily accessible to look at!

CatLady87

The only radiator is a wall one, so presume the pipes are laid in the walls rather than floor

FreeBear

CatLady87 said: Potentially. The radiator is in the far corner of the room (other side to the damp issue) but the floor is stone so not easily accessible to look at!

"Stone floor" - That got me looking at another thread of yours - https://forums.moneysavingexpert.com/discussion/comment/77673102/#Comment_77673102

Solid (double thickness) brick walls, Previous problems with down pipes & guttering which have now been resolved.. You probably won't like this, but any damp "treatments" were really a waste of money. Lime plaster and breathable paints (lime wash, clay) are the best solutions for an old property. Modern "waterproof" render/plaster, vinyl paints, etc all conspire to trap moisture in the walls. Gypsuma plaster (as you have found out) eventually turn to mush, and paint bubbles up & flakes off.

If you can find a local craftsman who can do lime plastering, it would be a much more sympathetic repair (in my opinion) and much more in keeping with the building - Some plasteres can "do" lime plastering (just avoid those that recommend Limelite Renovating Plaster it has cement in it). Or if you're feeling adventurous,  give it a go yourself.

CatLady87

Wow, thank you. I’d never thought of it this way. What about the guttering issue made you make the connection?

So do you think another damp proofing course would be a bad idea on that basis? It’s better to find a craftsman?

Thanks so much

CatLady87

I should add the house doesn’t have foundations (no cellar) and walls made of stone. Approx 1870s build 😱

Rural_Puppy

What sort of damproofing treatment was it that was done?
Something chemical injected into the stone walls? 
Or tanking?
Or just replastering?
Or something else?

CatLady87

To my shame, I’m not entirely sure! I remember them saying whatever damp proofing it was, it extended about a metre up the wall. Apologies, going to check with the contractor when he comes back. Gmail has deleted my old emails so I’ve got no reference point. Slack, I know.

FreeBear

CatLady87 said: Wow, thank you. I’d never thought of it this way. What about the guttering issue made you make the connection?

So do you think another damp proofing course would be a bad idea on that basis? It’s better to find a craftsman?

I looked at a previous thread, and simply put the two together - Seemed like a reasonable connection between gutter/downpipe issues and damp.

The fact that you still have ongoing problems with the wall demonstrates that further damp proofing will be wasted money - With the guttering issue resolved, the damp should clear up given time - The usual rule of thumb is a month per inch of wall thickness to dry out. On a 9" wall, that is (wait for it...) nine months. But now that winter has kicked in, I'd give it a full year.

Depending on where you are in the country, I'd give someone like Mike Wye or Ty Mawr a call and see who they would recommend in your area.

kdotdotdotdot

When you painted over the plaster, did you mist-coat it (making a solution of water and paint) or did  you just straight away apply the normal paint?  It won't be the cause of your damp plaster, but also won't do it any favours.  Gypsum plaster (I don't know about lime plaster if you're planning to get that) needs to be mist-coated first before painting.