Our landlady, Pani Janikowska, replaced some of our parquet floors for us, the coal-burning stoves that had been in here and been removed had left gaps and also burn marks on the wood. So we got to see the building construction first-hand. There is an eighteen-inch gap between floors filled with special "dust", basically light granules of dirt. Maybe for insulation, not sure. Then joists, then planks, then the parquet. This style of parquet floor is really common here. The walls tend to be extremely thick, and brick all the way through.
They apparently don't use nails here hardly at all. Well, though Władek did show me how he nails in the parquet pieces. They use this quick-hardening cement foam almost everywhere. Must make for quiet construction sites. All the windows they're replacing one-by-one all over the country are set in with this cement foam, pianka montazowa or "mounting foam". Władek, putting in the patch for the place where the stove used to be, used it. I gotta find some of this stuff when I get back.