First soil survey, then construction planning

Every house must stand on stable ground, whether on a foundation slab or a basement. According to the Association of Private Building Owners (VPB), many prospective homeowners are now aware of this and are inquiring whether a soil survey is included in the building contract.
While this is generally commendable, the mere fact that a soil survey is stipulated in the contract doesn't guarantee the ground's stability. The crucial factor is the survey's findings, which must be known before construction or planning begins, and therefore before the contract is signed; otherwise, additional work orders and costs may arise.

According to the VPB (Association of Private Building Owners), a typical problem is, for example, unstable soil, which usually has to be replaced at a cost. If this only becomes apparent after the contract has been signed and the soil conditions were not yet included in the costs, an addendum is necessary. Since building owners typically don't have time to obtain comparative quotes, the soil work can then quickly become expensive.

Furthermore, the VPB advises carefully examining such supplementary offers, as not all companies are very precise with measurements. Before paying the invoice, it should always be checked for plausibility: for example, whether the calculated cubic meters of excavation correspond to the information on the delivery notes from the transport company, whether this quantity of soil was actually transported to the landfill by the truck driver, etc.

Source: Association of Private Home Builders (Verband Privater Bauherren eV).