Insulating materials in the construction of floors

If, when finishing the interior of new buildings, when renovating old buildings or when converting, it is necessary to create subfloors under the floor covering, there is an opportunity here for the simultaneous implementation of thermal and soundproofing layers. If no dry screed is used, which are already equipped with hard foam pads (the so-called. composite elements), this substrate is insulated with boards of insulating materials, on which the screed elements are then laid.
You can find a wide variety of insulation boards in the insulation trade and at construction fairs, which can be used in the construction of substrates. The most commonly used are mineral fiber or rigid foam insulation boards. Some construction fairs offer soft fiber insulation boards : full of felt or cork, which from an ecological point of view do not raise any objections. The following preliminary considerations before building an insulation board floor should help, in order to avoid mistakes and unnecessary solutions when ordering and purchasing.

1. Above the massive ceilings, it is necessary to install anti-moisture insulation. For this, a polyethylene film of at least a thickness is required 0,2 mm. The foils should be spread flat, a clean and airtight ceiling in this way, that adjacent stripes overlap at least 30 cm. The foil strips can also be glued together. In addition, the foil should be approx. 10 cm to the surrounding walls. To ensure a truly floating arrangement of the dry screed boards, i.e.. arrangement not touching the walls, puts itself around, at the walls, end strips of insulation materials with a thickness of approx 2 cm.

2 Dry mineral fiber screed insulation boards can simply be cut with a knife. Laying should be done with rearrangement of the gaps, and not for cross slots, the insulation boards must fit snugly against each other.
Gap, the air-permeable effect of the edge strips of the insulating material, which arises around the arrangement of the dry screed elements. After laying a dry screed, the insulating material is cut with a knife and protruding above the floor.

3 For thermal insulation of the lowest raw ceiling, or of the highest ceiling of an inter-story house, it is recommended to make the floor on the joists. Here, too, the concrete ceiling must first be thoroughly cleaned of mortar residues, before a polyethylene foil is placed as an anti-moisture insulation.
The distance between the floor joists depends on the intended thickness of the dry screed elements (e.g.. chipboard), relatively – when laying the finished parquet elements directly on the joists - according to the parquet manufacturer's laying guidelines. When purchasing insulation boards, choose their width in this way, so that they can fit tightly between the floor joists.
Floor joists are laid loosely on the edge strips of insulation material with a thickness of. 1-2 cm, as screwing them to the ground would destroy the resulting insulation improvement from the sound of footsteps. When laying chipboards or gypsum-fiber boards on the joists, they are screwed with construction screws to the floor joists.

4 You can also use mineral fiber insulation boards to insulate wooden beam ceilings, hard foam, cork or soft fibreboard. They should be so selected in their width, so that they can fit tightly between the beams.
Even better thermal and noise insulation is achieved by arranging the insulation boards in two layers, about staggered gaps. When purchasing, it must then be taken into account, that the thickness of the boards is approximately half the height of the insulation. For this, double the amount of insulation boards is needed.

A specialist advises
In order to avoid soaking and rotting, wooden ceilings must under no circumstances be covered with polyethylene films.