The foundation base must be sufficiently stable and frost-free . The load-bearing capacity is usually determined by the soil survey . Frost-free means that the foundation level is so deep in the ground that it does not freeze even in severe winter; in Germany this usually requires a depth of 80 to 100 cm. The conditions are specified in DIN 1054 .
In the case of dams in Germany, the height of the barrier structure above the foundation level is one of the decisive factors for the classification according to DIN 19700 in dam class 1 or 2. The other criterion is the total storage space .