We are renovating the house, the old floors were on joists.
We decided not to put screed on the floor and make new floors on adjustable beams. The joists will be rigidly fixed to the floor slabs with metal anchors. Between the joists are laid two layers of absorbent wool: 8-10 mm thick rock wool. On the beams are laid 2 layers of plywood 18 and 10 mm thick, and then linoleum. Questions:
1) How to decouple the plywood from the joists to insulate the sound, or is it better to decouple the plywood layers with a spacer? And then how should the plywood sheets be attached to the joists and to each other?
2) What kind of mineral wool should be used for sound insulation in this case, and what kind of spacers can be used between the joists and the plywood?
The joists are already anchored, so it is not necessary to abandon the use of dowels.
It is better to decouple the beams from the concrete floor, otherwise they will squeak, and if objects fall or there is a commotion, the noise will be transmitted to the neighbors.