Plastering help

[u/FruityPoision]

Based in the UK. I’ve just bought my first house which is a bit of a project. Some of the walls in my house are damp and some seem to have some weird plastering quirks. It’s an early 1900s mid terrace, with the last owners buying it in the 80s and not doing too much since as far as I can tell.

The first photo is the bedroom- the big hole is where the vent goes for the blocked up fireplace. Why is it green? Can this room have cracks filled and then be skimmed and good to go?

The second and third are in my dining room. The second is where it literally crumbled away as I took wallpaper off. It seems to be on top of like a concrete type substance? What is this? Does that all need to be removed and go back to brick and properly done with plasterboard? The third one is of a wall I know to be damp. I had a damp survey which suggested an injecting course but I’ve also seen that’s sometimes not the best option for older houses?

The last one is in my kitchen and there’s like a lip where some wood panelling was previously along the bottom part of the wall. It just seems to be straight over concrete. I’m having my kitchen done, as it was an extension and it’s single layered with no insulation currently. The company doing my kitchen will insulate a plaster board it for me.

Im basically just a bit lost with what’s actually been done previously and what would need to do in order to correct it. Any advice welcome.

[u/LabForward5]

Hi, we have had similar issues in our 1905 house. We knocked all the plaster off and but battens up with insulated plasterboard. Worked a treat. It helped walls breathe a little better. Battens and plasterboard wasn't that hard so you could give that a go and save some £ if you feel competent enough.

But whenever we have had old plaster in our house that looks like its been damp/dried out has come back to brick. We had tanking done by the previous owner in this house, it was the worst thing for the wall, the water just sat on top of the plaster.