Lime vs Gypsum plaster

[Cakecrumbs]

Hello, having a bit of a dilemma and looking for some advice
Have some rooms that need plastered but currently they have lime plaster, walls are brick cavity walls on external walls with the lime plaster straight on to the brick.
Internal walls are lath and lime plaster. Rooms needs skimmed and some areas a bit more work done.
We've had quite a few people out to quote but everyone giving different advice and now we are so confused.
1}hace been told we can't skim using lime plaster
2)we are worried about damp if we used gypsum on to lime plaster.

Could we line the external walls with insulated board then skim with gypsum? Can we skim directly onto the lime with gypsum on the internal walls?

how old is the house?

Where is it?

Is it brick or stone?

is it damp?

You can skim on lime plaster if its sound. Ive had it done. There must be no damp.
You can just board over everything with, I think, Foil backed plaster board.
I wouldn't skim over lath and plaster as lime plaster is flexible, relatively to gypsum and the gypsum will crack.
If the walls aren't too bad if its stripped back to bare plaster (that includes the paint) you can sometimes paint it white, then fill and sand and then paint again. the room I did this way looks as good as the skimmed one.

If the house is in anyway damp you need to keep the lime plaster and only paint it with lime plaster compatible paint. I just used lime wash.

oops, sorry, brick cavity walls you say. Interested to know the age.

Bear in mind that the people you talked to may not be skilled in lime plastering.

you can internally insulate, dryline and skim with gypsum if you want. If doing that I would knock off all the existing plaster from those external walls first, before having the wiring renewed (in oval conduit) and deep boxes positioned.

Downstairs is 1700 and something and stone. Upstairs is around 1930 and brick cavity wall.
There was some damp on gable wall where there was some sort of weird sticky residue too and where they had put some gypsum on the wall. Not the whole wall though and the house had been empty for over a year.
Had roof checked and flashing round chimney breast replace and a few tiles but not major issues were found. House doesn't feel damp overall.
Felt more like it was condensation damp that water ingress damp if that makes sense.

Thanks for the replies.
One of the people I talked to was a specialist lime plasterer. I don't think I had realised you can't use lime plaster for skimming as we had been relying on that approach!

So are you talking now about the upstairs rooms with brick cavity walls and gypsum plaster? We need to talk about the stone and lime walls separately. Treatment will be different.

Yes just upstairs walls just now but they currently have lime plaster on them just now and I am stuck with what to do with them.
Will definitely deal with downstairs separately although it is in a better state anyway

Sorry if I am being confusing, all info I have given is relating to upstairs wall (other than mentioning what the downstairs is made of)

If the upstairs walls are completely dry just skim over it. The walls need to be dry to the touch. In the area I live its really common but only if its dry. My house is a solid stone walled terrace and the lime was skimmed three years ago and its great.
Lime plaster is usually a slightly rougher finish, even with a flat finish. I had a whole listed house done in lime plaster it was great.
Im not keen on dry lining as it basically hides damp problems until they cause really major problems.

Thanks, do you mean skim over it in lime or gypsum?

In gypsum, sometimes the plasterer will coat the wall first in some blue grainy stuff, can't remember its name, especially if there's paint on the plaster to ensure the new plaster sticks.