What ventilation does code require for an interior bathroom with no window in a Moncton apartment building conversion?

Interior bathrooms in apartment conversions must have mechanical exhaust ventilation that removes at least 25 L/s (50 CFM) continuously or 50 L/s (100 CFM) when occupied, according to the National Building Code of Canada 2020 edition that New Brunswick has adopted (effective May 1, 2025 for new applications).

For your Moncton conversion project, you'll need to install an exhaust fan that either runs continuously at the lower rate or operates at the higher rate with occupancy controls like a humidity sensor, motion detector, or manual switch with timer. The fan must exhaust directly to the exterior — never into an attic, crawl space, or other interior area. In apartment buildings, this typically means ducting through an exterior wall or up through the roof system.

Ductwork requirements are equally important for code compliance. Use smooth, rigid metal dubing where possible, with insulated flexible duct only for final connections. Keep runs as short and straight as possible — every elbow reduces airflow efficiency. The duct must be sealed at all joints and terminate with a proper exterior wall cap or roof jack that prevents backdrafts and weather infiltration.

Since this is an apartment building conversion in Moncton, you'll need a building permit from the City of Moncton Planning & Development department (506-856-4375). The conversion will also trigger requirements for fire separation between units, proper egress, and potentially upgraded electrical service. Each bathroom will need GFCI protection and proper lighting levels.

Professional installation is strongly recommended for apartment conversions. The electrical work requires a licensed electrician (licensed through NB's Technical Inspection Services), and you'll need an electrical wiring permit from NB Power (1-800-615-0522) before starting. The mechanical ventilation may also require coordination with the building's existing HVAC system, especially in older Moncton buildings where adding multiple exhaust penetrations can affect the building envelope.

Start by contacting Moncton's Planning & Development office to confirm the specific requirements for your building type and discuss the permit application process. They can clarify whether additional ventilation requirements apply based on the building's age, construction type, and intended occupancy.