Hello, we have a house built in '62 where the foundation wall (crawl space with dehumidifier) is plastered with so-called roughcast. It looks decent but has come loose in some places, and the ground level is somewhat lower now in a few areas since we drained and there is completely missing plaster. The foundation is built with hollow cement blocks. Now to the question, can I smooth plaster directly on the old plaster since it seems to stick well and is coarse enough that the smooth plaster should adhere properly? Or do I have to either chip off the old plaster completely or put masonry mesh on the existing one? It has been painted on top of the roughcast, but I don't know what type of paint it could be. Can I just wash it with paint cleaner and apply c-plaster? Regular or KC plaster?
I have almost scoured the internet for answers without finding any 😅
