Do I need a bathroom fan if I have a window?

Yes, you still need a bathroom fan even with a window. The Ontario Building Code requires mechanical ventilation in all bathrooms, regardless of natural ventilation sources like windows.

Why both are necessary: Windows provide natural ventilation when open, but they're not reliable year-round in Ottawa's climate. During winter months, you're unlikely to open a window in your bathroom, leaving you without proper moisture removal. Bathroom fans provide consistent, controlled ventilation that operates regardless of weather conditions or whether you remember to open the window.

Code requirements in Ottawa: The Ontario Building Code mandates that bathrooms have mechanical ventilation capable of moving at least 50 cubic feet per minute (CFM). This requirement exists specifically because natural ventilation alone isn't sufficient to prevent moisture problems that can lead to mold, mildew, and structural damage.

Proper ventilation strategy: The most effective approach combines both - use your exhaust fan during and after showers or baths to quickly remove moisture, and open the window when weather permits for additional fresh air circulation. Your fan should run for at least 30 minutes after showering to ensure all moisture is removed.

Sizing and placement matter: For Ottawa bathrooms, choose a fan rated for your room size (typically 80-110 CFM for average bathrooms) and ensure it vents directly outside, not into your attic space. Poor ventilation is one of the leading causes of bathroom renovation problems we see, as trapped moisture damages drywall, flooring, and framing over time.

For proper fan installation that meets Ontario Building Code requirements, consult with a licensed contractor who can ensure adequate ventilation for your specific bathroom layout.