A German customer does not have to pay the full price for defective work. Section 641 of the Civil Code lets him refuse part of the payment as long as he can demand that the defect be fixed. The law also says how much he may keep. angemessen ist in der Regel das Doppelte der für die Beseitigung des Mangels erforderlichen Kosten. As a rule, the appropriate amount is twice the cost needed to remove the defect. If a repair costs 1,000 euros, the customer may hold back 2,000 euros.
Lawyers call this the Druckzuschlag, the pressure surcharge. A building trade publisher explains its purpose. It is meant to make sure that the contractor fixes the defect quickly and properly. Until 2009 the law set the amount at three times the cost.