The plaster in our rented apartment was falling off the wall in two places. In the entrance hall huge lumps of plaster were coming off in our hands. This wall is next to a room which is under the steps of the main house and literally has water running into it when it rains. The house is well over a 100 years old, and I think renovations in the past were basically skin deep.
The other problem area is the hallway which has plaster coming off in a line outside the bathroom - presumably from a pipe is leaking in the wall behind.
We've stripped much of the crumbling plaster off the wall at the entrance, the plaster seems to have been applied in multiple layers, and at some places it's corroded all the way through to the brick. So there are the remains of hard flat layers, some crumbling plaster, and some exposed brick. We haven't touched the other wall yet.
Here's my question - whats the cheapest, longest lasting solution we can do ourselves (as DIY noobs). Can we just throw up some kind of plaster, or plasterboard on both the entrance and corridor? If what, which one should we get and what tools do we need to apply it.
Pictures and video of both areas here - https://imgur.com/a/XaNGMkX Thanks in advance for the advice.
Edit - re: questions about the landlord. It's not possible to get the landlord to help, or pay for the repairs in this case. Reasons are too complicated to go into here. But while we're not likely to get in trouble for any repairs made, we also can't expect any help.
Edit - re: leak. There isn't a 'leak' per say. The water is coming in from a completely uninsulated 'scullery' type 'room' under the houses external steps. This would cost a huge amount to have repaired, and that's simply not happening any time soon. So this is a stopgap.