The Ontario Building Code | Protection Against Depressurization
188.8.131.52. Protection Against Depressurization
(1) When determining the need to provide protection against depressurization, consideration must be given to,
(a) whether the presence of soil gas is deemed to be a problem, and
(b) the presence of solid fuel-fired combustion appliances.
(2) Where a solid fuel-fired combustion appliance is installed, the ventilation system shall include a heat recovery ventilator that is designed to operate so that the flow of exhaust air does not exceed the flow of intake air in any operating mode, and that complies with the requirements of Article 184.108.40.206.
(3) The provision of make-up air is not required for mechanical exhausting devices operating a subfloor depressurization system installed for the purpose of reducing the risk of radon ingress.