Ottawa By-law 2013-416, s. 36 — Property Standards By-law

1) Every habitable room, except for a living room and a dining room, shall be provided with natural ventilation which shall,

• a) consist of an opening or openings with a minimum aggregate unobstructed free flow area of 0.28 m (3 sq. ft.); and
• b) be located in the exterior walls or through parts of skylights which are capable of being opened. 2) Despite subsection (1), an opening for natural ventilation is not required if mechanical ventilation is provided which changes the air once each hour. 3) Every room containing a water closet shall be provided with an opening or openings for natural ventilation located in an exterior wall or through skylights which are capable of being opened, and all such openings shall have a minimum aggregate unobstructed free flow area of 0.09 m (1 sq. ft.). BY-LAW NO. 2013-416 4) An opening for natural ventilation as required in subsection (3) may be omitted where a system of mechanical ventilation has been provided, such as an exhaust fan with a duct leading to outside the building. 5) Every enclosed attic or roof space shall be vented by openings to the exterior to provide 2 2 at least 0.09 m (1 sq. ft.) of unobstructed vent area for every 27.9 m (300 sq. ft.) of attic or roof space. 6) The vents required by subsection (5) may be roof, eave or gable-end type or any combination thereof. 7) In multiple dwellings, every laundry room, garbage disposal room, boiler room and storage garage of the building shall be adequately ventilated. 8)

Where a system of mechanical ventilation is used,

• a) it shall be maintained in good working condition, regularly cleaned and kept in good repair; and
• b) the ventilating duct which is on the exterior wall shall be located not less than 1.8 m (6 ft.) from any skylight, window, ventilator or other opening located in an adjacent building and shall be directed and operated in such a way as to not constitute a nuisance. 9) All systems of mechanical ventilation or air conditioning shall be maintained in good working order. BASEMENT, CELLAR OR UNHEATED CRAWL SPACE