In general terms, builders are required to ensure that the materials used in constructions are of sufficient quality, and from an appropriate source. However, the quality of materials is also covered by the CE marking in accordance with the Construction Products Directive (89/106/EEC), the Low Voltage Directive (73/23/EEC and amendment 93/68 EEC), and the EMC Directive (89/336/EEC) as amended by the CE Marking Directive (93/68/EEC).