Eliminating odors and soot from a house with clay plaster - ideas?

Hello forum,

Last year we bought a house in Hungary and want to renovate it. The year of construction is probably around 1950. Everything solidly built from field-fired bricks (40 cm exterior wall), unfinished on the outside, inside walls and ceilings completely with clay plaster, the floors tiled, and in 2 rooms wooden floors.

At the time of purchase, the house was unfortunately completely - partly 2m high - cluttered, and the floors almost completely covered with PVC, newspapers, furniture, laundry, carpets, and garbage bags. The walls were completely blocked with cabinets and trash so that there was no ventilation anywhere. In the kitchen, there was moisture under the PVC on the tiles, but it dried within 2 weeks. In one of the rooms, the wooden floor partially dissolved under piles of garbage, PVC, and carpets - this will be replaced soon. We hope to save the other wooden floor by sanding it. In one of the rooms, black moldy traces formed on the outer walls behind the cabinets. On the roof, there were 2 larger leak points, through which the interior of the house was always supplied with moisture :(
How long it stood empty before the purchase cannot be determined, but we assume at least 1-2 years.

We completely cleared out the house and have now let it dry for 8 months. Fortunately, windows and front door are (currently) far from tight, which gives us a certain air exchange. A critical, wet spot on the exterior wall could be traced back to a defective gutter and is now also dry.

Now we have 2 problems where we are not sure how to proceed:

1. The previous owners heated the kitchen for years with a defective wood stove. The room stinks unbearably of fire, like after a major fire. Ceiling and walls are BLACK!


2. The entire house smells strongly of mustiness and other unpleasant "leftovers."

Basically, we have to clean all surfaces from dirt, soot, and mustiness.
We would treat the tiled floors with baking soda as an odor binder and possibly a steam cleaner. Wooden floors, doors, windows would be sanded. We have also considered an initial ozone treatment to kill all mold spores and eliminate some of the odors.
What do you think about that?

How do we proceed with the clay plaster on the walls?
We thought about removing the top layer (maybe 2mm) with a plate sander and then applying a new fine clay plaster layer. The paint on the walls is going to be removed and repainted anyway. However, I fear that sanding will rub the mustiness and especially the black soot layer in the kitchen further into deeper layers (I would like to avoid removing the whole 2-3 cm of clay plaster). We had also considered cleaning with steam, but then again there would be a lot of moisture in the house...
How would you do it?

Thanks for your tips and suggestions

Even though I was impressed by what a small ozone generator can neutralize for the toilet, I’m afraid you can’t avoid gutting it. The mold is probably already deep in the plaster, where the ozone doesn’t reach that quickly. The smoke odor has certainly soaked through completely. But I’m just an amateur. Maybe someone experienced in restoration will weigh in...

A friend of mine helped dispose of things in a moldy apartment a few years ago and caught nasty mold spores. With just under 50% lung function, the infestation could be stopped. Life was permanently changed and unfortunately lasted much too short afterward. Last summer, it sadly ended in his early 60s. I miss him. Please be careful and wear protective clothing. Better to gut it than to keep any kind of harmful mold. Cutting corners in the wrong place would worry me.

For sanding the walls, we will definitely work with FFP3 masks and a vacuum cleaner with dust class H or exhaust to the outside. Do you think 2-3mm is enough here? The walls will be painted with lime paint afterwards, which to my knowledge strongly inhibits mold growth.

No, I think, as I said, not that it is enough. Take it all down.

The smell of burning can only be removed if the plaster is completely removed. And persistent musty odor would irritate me and prompt me to take a close look at the structural timbers in floors and ceilings. What is the floor construction on the ground floor?