Imagine my surprise! When I tore up my kitchen floor on Monday, I was truly astonished. Between the floor joists, cement had been poured. And on top of this, it was filled with sawdust (in some places). Why on earth would they have done that? In all the other rooms where I have torn up the floor and insulated, they used rough lumber as the subflooring. Not cement!!!
The house was built in 1926, has a crawl space with granite blocks, and it is bone dry underneath. The surface area of the ground floor is just over 100 m2, divided into a kitchen, living room with dining room, TV room, hall, and bathroom. The total area of the house is 197 m2. Everywhere except the kitchen, I have removed the old subflooring and replaced it with new material and insular with rock wool/glass wool.
It should be mentioned that the space under the kitchen cannot be accessed from the crawl space. The reason for this is that there is a basement under part of the area and a lot of stones have been placed as support for the central beam. Otherwise, there's plenty of space in terms of height. At least 1-1.5 meters in any case. Only in the sections above the basement have they used wood as subflooring. In the other sections, they seem to have filled it with stone and soil and topped it with cement.
In any case, I plan to chip away the cement and remove stone and soil/gravel as much as possible and build proper subflooring. Some floor joists need to be replaced as well. You can see that they have become a bit damaged precisely up to the height where the cement was. But they don't look rotten, just a bit eaten away by insects. Some joists haven't been completely debarked, which has caused some insect activity. The man who built the house had his own sawmill. Quite a bit of the wood still has bark on one side. It seems like they used edge boards here and there.
In some places, the beam is also a bit insect-eaten, but only where the bark was. I had Anticimex come out to check when I renovated the TV room, and they said it was nothing to worry about. The wood is sound a little bit further in.
Could they have put the cement there just because the area isn't accessible for inspection, hoping that it wouldn't suffer moisture damage in the subflooring? That was over 80 years ago.
Grateful for any answers.
/ Niclas
