This work examines which construction and plant engineering contracts are classified under the sales law according to § 651 of the German Civil Code (BGB), which came into effect on January 1, 2002, and which continue to fall under the law of contracts for work and services. It concerns contracts for the construction of buildings and civil engineering works as well as technical facilities of all kinds. Additionally, contracts for supplementary construction services will be analyzed. The contents of the Consumer Goods Sales Directive 1999/44/EC of May 25, 1999, are crucial for the scope of application of § 651 BGB. This results in construction and plant engineering contracts being subject to sales law to a much greater extent than under the law prior to December 31, 2001. Practice and jurisprudence will need to adapt to this change.