CSA A93:19 Airflow ventilators for the unoccupied spaces of buildings.
4 General requirements
Ventilators conforming to this Standard shall be classified as
a) Type A for installation on vertical surfaces;
b) Type B for installation on sloping surfaces;
c) Type C for installation on ridges;
d) Type 0 for installation on horizontal surfaces; and
e) Type E for installation on eave soffits.
Ventilator installation shall conform to the requirements of the manufacturer’s installation instructions.
Note: For installation of mechanical ventilators, refer to Annex Efor precautionary measures which should be
taken into account.
5 Physical requirements
5.1 Basic design
Ventilators shall be so designed that each can be installed and securely fastened. Flashing joints shall be downslope. Intermittently-engaged mechanical ventilators should be equipped with a thermostat or a thermostat/humidistat to ensure that operation occurs when demand is present.
Materials used for ventilators shall be free from visible cracks and other defects, and shall be suitable for long-term use. In addition, they shall be made so that no protective coating is required at the building site, except for fasteners, shingles, or flashing sealing. Materials shall remain durable, semirigid, non-brittle, and firm, and shall not be significantly affected by exposure to ultraviolet radiation. Note: The products used for installing the ventilator on a roof system should be compatible with the ventilator material in accordance with the NBC.
5.3 Insect and rodent protection
Screen openings shall be a maximum of 10 mm (3/8 in) measured between any two points of a single
opening. Openings in small louvres without screens shall not exceed 10 mm (3/8 In) x 125 mm (5 in).
1) For ventilator caps in forced-air systems, refer to Annex c.
2) in areas of increased fire hazards, mesh openings and vents might need to be adjusted to prevent burning ember penetration. Refer to Annex D.
5.4 Fastener components
All fasteners used for assembly shall be compatible with other ventilator component materials. They shall be tightly fastened and provide protection against water penetration.
Type A ventilators shall be provided with flanges by which the ventilators can be fastened and sealed against water penetration.
The base flange of Type B ventilators shall provide a minimum of 75 mm (3 in) of flashing for the roofing material on the upslope side and a minimum of 50 mm (2 in) on all other sides.
Type C ventilators that have a base flange shall provide a minimum of 50 mm (2 in) of flashing to overlap the roofing material on each side of the ridge.
The base flange of Type D ventilators shall provide a minimum of 75 mm (3 in) of flashing for the roofing material on all sides. The stack shall be either one-piece construction or permanently sealed against water penetration.
5.6 Foundation ventilators
Foundation ventilators shall incorporate devices that can be opened or closed to regulate the airflow.CSA A93 pdf download.