A reinforced concrete slab on a gravel base is a high-quality foundation option.
Dig below the frost line (approx. 60 – 80 cm deep, depending on the region), then fill and compact the excavated area with gravel (grain size up to 35 mm). Then level with gravel (grain size up to 6 mm) up to a thickness of approx. 3-5 cm. The vapour barrier (plastic membrane at least 150 μm thick) is laid in this levelling fill. The concrete foundation with 1 to 2 layers of structural steel grid is placed on top of this. The concrete slab should be approx. 10 - 15 cm thick.
The graduated foundation slab, with a circumferential step of 2 x 7 cm, is an ideal design. The floor profile is attached to the surface using the screws and dowels supplied.
Please note that it is not possible to use the aluminium floor frame with the graduated concrete foundation. A sealant can also not be applied to protect against water ingress.
- Frost-proof excavation of the building site
- Construct the gravel base
- Apply levelling fill
- Lay vapour barrier
- Pour the foundation