expansion belt
It serves to prevent thermal expansion during the expansion of the floor heating and to prevent the transmission of noise between structures, e.g. wall and floor. At the same time, thanks to the additional film, it prevents the screed from leaking under the insulation layer and thereby possibly lifting the entire floor heating layer.
What should a quality expansion belt contain?
The minimum thickness of the expansion belt should not be less than 8mm. Its height does not matter so much, because we do not have to put it on the lowest layer of the floor, on the contrary, practical notches are more important, with the help of which it is possible to tear off the protruding piece of the dilatation strip after pouring with screed. Each dilatation belt should contain an additional film, the so-called a welded apron that serves as a compact joint between the wall and the floor and prevents the screed from seeping under the layer of insulation. The black self-adhesive back side is very practical, it will save you a lot of time when laying.
Depending on the total height of the floor for underfloor heating, we decide on which layer we will start laying the expansion strip. If we have purchased the most sold dimension of the dilatation belt with a thickness of 8 mm and a height of 160 mm, then of course we cannot place it on the very bottom layer, as long as the total structural height of the floor exceeds the height of the belt. In this case, first lay a layer of construction floor polystyrene and only then fasten the dilatation strip to the wall. The self-adhesive layer will serve us to fasten it to the wall, at least until we press the expansion strip with another layer of floor insulation or a system board for floor heating. In a dusty environment, the effectiveness of the self-adhesive layer decreases rapidly, but it is still sufficient for one person to handle this part of the assembly. Without a self-adhesive layer, it is more practical to call a helper who will attach polystyrene or a system board right behind the spread belt. Make sure that the notches used to tear off the strip protruding above the screed are on the upper side. Pull the welded foil up, then fix it with the outermost pipe for underfloor heating. Also because of this insulated connection between the wall and the floor, it is not recommended to replace the expansion strip with thin construction polystyrene.
