Ventilation: Approved Document F, Volume 1 — Dwellings

F1(1) O N L I N E V E R S I O N b. If the dwelling already has mechanical ventilation, the centralised system could be extended into the additional room. 3.19 For purge ventilation in a new habitable room in a dwelling, paragraphs 1.26 to 1.31 should be followed. 3.20 For a new habitable room in a dwelling, ventilation location should follow paragraphs 1.9 to 1.31, performance testing should follow paragraph 1.32 and controls should follow paragraphs 1.33 to 1.37. Addition of a conservatory to an existing building 3.21 The guidance in this section applies to conservatories with a floor area that exceeds 30m2. Conservatories with a floor area that does not exceed 30m2 are exempt from the Part F requirements. 3.22 The general ventilation rate for a new conservatory and, if necessary, adjoining rooms could be achieved using background ventilators. The guidance in paragraphs 1.42 to 1.44 should be followed regardless of the ventilation provisions in the existing room adjacent to the conservatory. 3.23 For purge ventilation in a new conservatory, paragraphs 1.26 to 1.31 should be followed. 3.24 For a new conservatory, performance testing should follow paragraph 1.32 and controls should follow paragraphs 1.33 to 1.37. Addition of a wet room to an existing dwelling 3.25 When a wet room is added to an existing dwelling, whole dwelling ventilation should be extended and extract ventilation should be provided by one of the following means. a. Intermittent extract, as specified in Table 1.1, and a background ventilator of at least 5000mm2 equivalent area. b. Continuous extract, as specified in Table 1.2. c. Single-room heat recovery ventilator, as detailed in paragraph 3.26. 3.26 If a continuously running single-room heat recovery ventilator is used in a wet room, it should use the minimum high rate given in Table 1.2 and 50% of this value as the continuous rate. A background ventilator is not required in the same room as the single-room heat recovery ventilator. 3.27 Internal doors should allow air to move within the dwelling by providing a free area equivalent to a 10mm undercut in a 760mm wide door. Doors should be undercut to achieve one of the following. a. If the floor finish is fitted: 10mm above the floor finish. b. If the floor finish is not fitted: 20mm above the floor surface. 3.28 For purge ventilation in a new wet room, paragraphs 1.26 to 1.31 apply. 3.29 For a new wet room, ventilation location should follow paragraphs 1.9 to 1.31, performance testing should follow paragraph 1.32 and controls should follow paragraphs 1.33 to 1.37. 26 Approved Document F Volume 1, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N