Put simply, the regulations apply to ‘building work’. Since this term could have any number of meanings, it is closely defined in regulation 3 of the Building Regulations 2000 (as amended) (referred to as the 2000 Regulations in the remainder of this chapter) and is explained in detail in Section 4.1.1. Building work (whether to a new or existing building) must comply with the applicable requirements of Schedule 1 to the 2000 Regulations (see regulation 4). These requirements are phrased in functional terms and cover such aspects of building design and construction as structural stability, safety in fire, resistance to dampness, ventilation, drainage, waste disposal, etc. They are given in full in Appendix 1. It is possible that satisfying one part of Schedule 1 can cause a contravention of another part (e.g. from a purely structural viewpoint, in some circumstances, external walls could be constructed of 190-millimetre-thick masonry; however, this form of construction would be unlikely to satisfy the weather-resistance requirements of Part C and the heat-loss requirements of Part L). Therefore, regulation 4(1)(b) prevents this by requiring that all parts of Schedule 1 be complied with (one requirement must not cause a contravention of another). When carrying out work to existing buildings it is not always necessary to bring the building up to the full requirements of all parts of Schedule 1; however, work to existing buildings must be carried out so that, when the work is complete, the building is not made worse in relation to compliance with the regulations than it was before the work commenced.