Appendix B: Types of work covered by this approved document

1. This approved document gives guidance on what, in ordinary circumstances, may be considered reasonable provision to comply with the requirements of regulations 26, 26A and 40 of, and Part L of Schedule 1 to, the Building Regulations for those creating new dwellings. In addition, this approved document gives guidance on how to comply with regulations 25A, 27, 27A, 43 and 44 of the Building Regulations and regulation 20 of the Building (Approved Inspectors etc.) Regulations 2010 where an approved inspector is the BCB.

  1. Live–work units
    1. Mixed-use developments
      1. Material changes of use

        Live–work units

        2. If a unit contains both living accommodation and space to be used for commercial purposes (e.g. as a workshop or office), the whole unit should be treated as a dwelling, as long as the commercial part can revert to domestic use. This can be the case if, for example:

        a. there is direct access between the commercial space and the living accommodation; and

        b. both are contained within the same thermal envelope; and

        c. the living accommodation occupies a substantial proportion of the total area of the unit.

        Note: Sub-paragraph c means that, for example, the presence of a small flat for a manager in a large non-domestic building does not result in the whole building being treated as a dwelling. Similarly, if a room is used as an office or utility space within a dwelling, that does not mean that the building should not be treated as a dwelling.

        Mixed-use developments

        3. When constructing a dwelling as part of a larger building that contains other types of accommodation, sometimes called a mixed-use development, use this Approved Document L1A for guidance in relation to each individual dwelling. Approved Document L2A gives guidance relating to the non-dwelling parts of such buildings, such as heated common areas, and in the case of mixed-use developments, the commercial or retail space.

        Material changes of use

        4. The act of erecting a new dwelling is not a material change of use. Approved Document L1B applies where a dwelling is being created in an existing building as the result of a material change of use of all or part of the building.

        • Table 1 Fuel factor Table 1 Fuel factor
        • Table 1 Fuel factor Table 1 Fuel factor
        • Table 2 Limiting fabric parameters Table 2 Limiting fabric parameters
        • Table 3 U-values for party walls Table 3 U-values for party walls
        • Table 4 Summary of concurrent notional Table 4 Summary of concurrent notional dwelling specification
        • Table 4 Summary of concurrent notional dwelling specification (continued) Table 4 Summary of concurrent notional dwelling specification (continued)
        • Parameter Parameter