The building completion insurance and the construction warranty insurance are innovative collaterals for the German insurance and building law in the construction business. They constitute a renunciation of the insurance law dogma of the non-insurability of insolvency and botch in construction. They offer insurance cover for the building contractor's performance liability and liability for defects and for the benefit of the builder-owner and his risk of insolvency of the building contractor from the building completion phase until the commencement of the statute of limitation for certain claims of the builder-owner. The author jurisprudentially analyses the practicability and therefore the expedience of the building completion insurance and construction warranty insurance in respect to its pursued objectives regarding the builder-owne's insolvency protection and the insurance of the liability of defects in the time frame of the statute of limitation. The achievements of a system internal and system competing examination in comparison to the performance guarantee and warranty guarantee finally result in practice-oriented recommendations and modification proposals for optimising the system of the building completion insurance and construction warranty insurance.