London : Règlement no CP-24, art. 4.8.6 — Ventilation – Provided – Maintained Every habitable room except for a living room and a dining room shall be provided and maintained with natural ventilation which shall

Ventilation – Provided – Maintained Every habitable room except for a living room and a dining room shall be provided and maintained with natural ventilation which shall:

• a) consist of an opening or openings with a minimum aggregate unobstructed free flow area of 0.278 m 2 (3 sq ft), and
• b) be located in the exterior walls or through openable parts of skylights, or
• c) mechanical ventilation which shall change the air once each hour;
• d) every washroom shall be provided with an opening or openings for natural ventilation located in an exterior wall or through openable parts of skylights and all such openings shall have a minimum aggregate unobstructed free flow area of 0.092 m 2 (1 sq ft);
• e) an opening for natural ventilation may be omitted from a bathroom or toilet room where a system of mechanical ventilation has been provided, such as an exhaust fan with a duct leading to outside the dwelling;
• f) every enclosed attic or roof space shall be vented by openings to the exterior to provide at least 0.092 m 2 (1 sq
• ft) of unobstructed vent area for every 27.9 m 2 (300 sq
• ft) of attic or roof space;
• g) the vents required by clause
• (c) may be roof, eave or gable-end type or any combination thereof;
• h) a crawl space or non-habitable basement space shall be adequately ventilated to the exterior by natural or mechanical means;
• i) in residential buildings with multiple dwelling units, every laundry room, garbage disposal room, boiler room, storage garage, public corridors and other similar public rooms or spaces of the building shall be adequately ventilated.