Clay lining in 1940s basement?

[Appeplan]

My partner and I have just bought our first house, a neat villa with a mansard roof from 1942, about 90 sqm + 56 sqm basement. We plan to make the basement habitable in the future, with a laundry room, WC/relaxation area, and guest room.

Currently, the outer walls of the basement are asphalted (original), lacking drainage, with a classic basement smell, some plaster flaking from the walls, etc., but otherwise in good condition. According to the owner who has lived there for 50 years, there have never been any issues.

We plan to insulate and drain externally, remove the existing basement floor, dig out, insulate, and pour a new floor.
I'm wondering if it's possible to use clay plaster on the interior basement walls, as clay plaster is diffusion-open and can buffer moisture, which I think would be a good combination in a basement. Am I thinking correctly, or is lime plaster the way to go?

 

[Småbrukaren]

Congratulations on the house. The only reason not to go with clay plastering is probably the drying time, I suppose.

 

[Utsliten och utdömd]

No, use something like kc-puts instead.

 

[Appeplan]

Congratulations on the house. The only reason not to use clay plastering is probably the drying time, I guess.

Thank you very much! Good input, I thought the same thing. However, I can't find a single thread about people clay plastering basement walls. Maybe it's best to turn to companies that sell clay plastering products and ask.

 

[Appeplan]

No, go with something like lime plaster or similar instead.

Thanks for the input! What could be a disadvantage of clay plastering basement walls? It seems to be an untested method, I can't find any info about it.

 

[Småbrukaren]

Should have used plaster. The risk is that the clay retains moisture in the basement environment instead of being ventilated away.

 

[Utsliten och utdömd]

The biggest advantage of clay is that it moves quite similarly to wood, so you can achieve a smooth surface and reasonably airtight without the risk of it cracking, in a log/plank frame. I don't quite understand the advantage of clay plastering stone or concrete walls. If you have a basement smell today, it indicates poor ventilation and high humidity. You only risk getting mold with clay plastering that is reinforced with horsehair, grass, or hay, etc., in clay that also stores moisture.

 

[Appeplan]

As mentioned, the plan is to insulate and drain before I start renovating the basement interior. Considering your responses, I will be doing regular KC-plaster.