According to DIN EN 1997-1, every type of foundation must be protected against frost damage. Frost damage can occur when water freezes into ice. The increase in volume by 9 – 11 % when the aggregate state changes from water to ice can cause uplift in the soil. As the ice melts, the volume decreases again, so that in the course of the season, uplifts and subsidences can take place, causing serious damage to the foundation structure.
DIN EN 1997-1, No. 6.4 (2) describes the prevention of frost effects by insulation as one way of preventing frost damage. In this sense, a ring-shaped reinforced concrete foundation wall under the outer walls of a structure can prevent frost from penetrating under the floor slab. The depth of the frost apron depends on the risk of frost. Frost aprons influence the load-bearing effect of the floor slab and should therefore be planned and taken into account by the structural engineer.
Usual frost depths in Germany are 80 cm to 120 cm below the ground surface.
Source: bauwion
