Plastering & Rendering

Dry lining / Thermal insulating boards

Anonymous user 28/02/2024 - 2.57 PM

Hi, I've just bought a 3 bed semi that needs a full refurb. It's my first one and its in a bit of a state so I'm on a steep learning curve. I was wondering if someone could advise me on some plastering queries?... It's over 100 years old and I've been taking down the picture rails and ripping out the skirtings as some areas are in bad shape (warped/rotten). As I'm taking them off, larges chunks of rubble is coming off in places and exposing the brick. Whereas in some places the rubble is pretty secure. I say 'rubble' because it's a thin layer of sand coloured plaster, and an inch thick layer of black powdery stuff? Any idea what this is? It's black throughout the house. Is this some sort of plaster, or mortar? (It's not powdery in all places, just where it crumbles) The house had no central heating and the previous owner had put polystirene tiles on the front, back and side walls, but not on the interior walls. My plan is to hack off back to the brick on the front, back and side walls and use thermal insulating boards to dry line. On the interior walls I think I can get away with patching and skimming. My question is... Will a combination of thermal insulating boards on the insides of the exterior walls, and skimming the interior walls give me a significant increase in insulation, or do I need to hack off all plaster on all walls and completely dry line everything? Also, what are the most cost effecting type of boards to buy? How thick etc, where from, how much etc? Might sound like a stupid question to some if you but I'm new to this! Many thanks in advance.