Conservation of fuel and power: Approved Document L, Volume 1 — Dwellings

O N L I N E V E R S I O N R23(2), L1(a) Section 10: New elements in existing dwellings, including extensions General 10.1 This section provides guidance for new elements in existing dwellings, including all the following types of work. a. Providing a new thermal element in an existing dwelling – follow paragraph 10.1. b. Providing a replacement thermal element in an existing dwelling – follow paragraph 10.2. c. Replacing windows, doors or rooflights (controlled fittings) in an existing dwelling – follow paragraphs 10.3 to 10.6. d. Extending an existing dwelling – follow paragraphs 10.7 to 10.11. e. Adding a conservatory or porch to an existing dwelling – follow paragraphs 10.12 and 10.13. NOTE: Guidance for renovating elements in existing dwellings is given in Section 11. New and replacement fabric elements 10.2 The minimum standards in paragraphs 4.7 and 4.8 and Table 4.2 should be met for both of the following. a. New thermal elements installed in an existing dwelling. b. Thermal elements constructed to replace existing thermal elements. 10.3 For new and replacement windows, roof windows, rooflights and doors (controlled fittings), if the entire unit of that fitting is provided, all the following apply. a. Units should be draught-proofed. b. Units should meet the minimum standards given in Table 4.2. c. Insulated cavity closers should be installed where appropriate. 10.4 Building control bodies may accept, as evidence of compliance with the standards given in Table 4.2, a Window Energy Rating and/or Doorset Energy Rating from a certification scheme that provides a quality assured process and supporting audit trail from calculating the performance of the window through to the window being installed. 10.5 If a window is enlarged or a new one is created, either of the following should be met. a. The area of windows, roof windows, rooflights and doors should not exceed 25% of the total floor area of the dwelling. b. If the area of windows, roof windows, rooflights and doors exceeds 25% of the total floor area of the dwelling, compensating measures should be taken to improve the energy efficiency of the dwelling. Building Regulations 2010 Approved Document L Volume 1, 2021 edition 61 O N L I N E V E R S I O N