In 2016, Finnfoam introduced a new basic solution for edge-reinforced slabs
The solution uses specially cut, sturdy Finnfoam thermal insulation panels to create a casting mold, which is not dismantled after casting. An edge-reinforced slab, which is thermally insulated throughout, provides the best possible foundation solution for passive and zero-energy houses, because it completely eliminates thermal bridging from the foundation. The low water vapor permeability of Finnfoam prevents moisture transferring from the ground to the slab. Due to the high compressive strength of Finnfoam, the thermal insulation is also free from compression-related issues.
The panels are laid on a smooth, sealed base. The mold construction begins by placing down the Finnfoam LB300 bottom pieces of the edge molds, after which the upright Finnfoam LS300 walls are installed. The upright Finnfoam LS300 walls are 100 mm thick and a second 100 mm thick panel of regular Finnfoam is usually installed on their outside with insulation anchors to ensure sufficient thermal insulation of the structure and to provide support for the walls during casting. In addition, the wall support is secured with 5 mm stainless steel supports placed at approximately one-meter intervals and attached to the reinforcement of the slab.
A 200–300 mm thick layer of Finnfoam thermal insulation is placed as thermal insulation inside the edge-reinforcement based on the desired U value. Next, the slab reinforcement is carried out according to the structural plans, the necessary pipelines laid, and the edge-reinforced slab is cast. This solution significantly facilitates and speeds up the creation of an edge-reinforced slab and completely eliminates thermal bridging from the slab.
Further information on products designed for this solution (LS300 and LB300) can be found here.