The simplest technique for insulating a room with a wooden floor is to lay glass wool between the joists of the room below, with or without coating.
Glass wool preparation
This operation must be carried out carefully, because it is on this that the tightness of the insulation will depend. The first step will be to carefully measure the spacing of the joists at each end (the measurements may be different) and note them on the wall and for all spans. These measurements are then transferred to the smooth face of the glass wool plate, adding 5 mm of security. Using a metal ruler placed on the marks, the panels are cut with a very sharp instrument, avoiding tearing the glass wool.
Laying glass wool
The panels thus cut are then placed between the joists, reinforced side down, pressing well on the periphery to slightly compress the glass wool between the joists and thus avoid thermal bridges. The glass wool will then be fixed using cleats nailed to the joists which will wedge the insulation against the ceiling, without compressing it. These cleats should be carefully cut for a clean finish.
Laying of the covering
If the insulation has been installed in a basement, it is not essential to add a covering, but if it is a habitable room, we can fix a light covering to the battens which maintain the insulator, and possibly paint it.