Plastering a badly damaged wall

Question

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.

Answer 1

As commenters have suggested, there are 2 things unusual about your plan:

1. You're renting this place, and typically repairs on a rental are the duty of the landlord and not the tenant
2. As tenants, you're unable/unwilling to fully repair the cause of the crumbling plaster (moisture through the wall)

So this advice is for your particular situation, rather than generally advisable to anyone. Other readers will have much better luck and results getting their landlord to perform repairs, as this is their job.

You will quickly have mold problems with any repair unless you properly deal with moisture from the wall. The fastest way to do this is a moisture blocking "paint" such as Drylok. Note that this is not a permanent solution and mold is likely eventually, but these look like open spaces where you can monitor the surface.

Second and slightly better, you could apply sheets of rigid foam insulation directly to these walls and normal paint on that foam surface. The visible cracks and gaps may not be to your liking.

A more permanent and advisable way to cover these walls would be to clear any plaster remaining on the surface, then attach metal studs to the wall, insulate between with rigid foam (NOT fiberglass or cloth-based insulation which absorbs water) and then "drywall" with a paper-free non-nutrient wallboard (here we use Dens-Armor Plus) and then finish with paint.

The key is to not use components which absorb or interact with the continuous moisture you have, or mold will develop and you'll need to replace the surface again in short order.