Ventilation: Approved Document F, Volume 2 — Buildings other than dwellings

O N L I N E V E R S I O N F1(1) Replacing windows Existing windows with background ventilators 3.5 If the existing windows have background ventilators, the replacement windows should include background ventilators. The new background ventilators should comply with the following conditions. a. Not be smaller than the background ventilators in the original window. b. Be controllable either automatically or by the occupant. If the size of the background ventilators in the existing window is not known, the ventilator sizes in paragraph 3.6 may be applied. Existing windows without background ventilators 3.6 Replacing the windows is likely to increase the airtightness of the building. If ventilation is not provided via a mechanical ventilation system, then increasing the airtightness of the building may reduce beneficial ventilation in the building. In these circumstances, it is necessary to ensure that the ventilation provision in the building is no worse than it was before the work was carried out. This may be demonstrated in any of the following ways. a. Incorporating background ventilators in the replacement windows equivalent to the following. i. Occupiable rooms. • For floor areas up to 10m2 – minimum 2500mm2 equivalent area. • For floor areas greater than 10m2 – minimum 250mm2 equivalent area per m2 of floor area. ii. Domestic-type kitchen – minimum 8000mm2 equivalent area. iii. Bathroom (with or without a toilet) and shower rooms – minimum 4000mm2 equivalent area per bath or shower. iv. Sanitary accommodation (and/or washing facilities) – minimum 2000mm2 equivalent area per WC. b. Other ventilation provisions, if it can be demonstrated to a building control body that they comply with the requirements of paragraph 3.2. NOTE: If it is not technically feasible to adopt the minimum equivalent areas set out in paragraph 3.6, the background ventilators should have equivalent areas as close to the minimum value as is feasible. NOTE: If an exposed façade is close to an area of sustained and loud noise (e.g. a main road), then a noise attenuating background ventilator should be fitted. 19 Building Regulations 2010 Approved Document F Volume 2, 2021 edition O N L I N E V E R S I O N