Windows and doors Light, View and Ventilation
Windows and doors with glazing provide light, view and ventilation. Except for bedrooms, which require windows as a means of egress from fire, the NBC does not require other rooms to have windows. However, it is recommended that certain rooms have windows large enough to admit daylight because of the psychological benefit they provide occupants and to provide natural daylighting. A general rule is for living rooms, dining rooms and bedrooms to have glazing equal to at least 10 per cent of the area of a room. Other rooms, such as family rooms, should have window areas equal to at least 5 per cent of the floor area of the room.
Operable windows provide natural ventilation and can reduce the need to operate mechanical ventilation during non-heating seasons. Windows used for natural ventilation should have an unobstructed, operable window area of at least 0.28 m2 (3 sq. ft.). Bathrooms should have a window area of at least 0.09 m2 (1 sq. ft.), or else require mechanical ventilation.
Because fire can spread from windows to adjacent houses, building codes place strict limits on the amount of glazing in walls that are close to property lines. Unprotected, glazed openings are not permitted in walls that are within 1.2 m (4 ft.) of a property line. The allowable area of windows in walls more than 1.2 m (4 ft.) from a property line depends on their distance from the property line and the area of the wall facing the property line. Consult the local building department for specific requirements.
Minimum dimensions for egress windows