Why is my bathroom always humid?

Bathroom humidity is typically caused by inadequate ventilation combined with moisture from hot showers, baths, and daily use. Without proper air circulation, water vapor gets trapped and creates that persistently damp feeling.

The primary culprit is usually an undersized or poorly functioning exhaust fan. Many older Ottawa homes have builder-grade fans that move only 50-80 CFM (cubic feet per minute), which isn't sufficient for most bathrooms. The fan should be sized to move the air volume of your bathroom 8-10 times per hour. For a typical 8x10 bathroom, you need at least 100-120 CFM capacity.

Poor ventilation habits also contribute significantly to humidity problems. The exhaust fan should run during showers and for at least 30 minutes afterward to remove lingering moisture. Many homeowners turn it off too quickly, leaving water vapor to condense on surfaces and create that humid environment.

In Ottawa's climate, inadequate insulation and air sealing around the bathroom can worsen humidity issues. Cold exterior walls create condensation points where warm, moist air meets cool surfaces. This is especially common in older homes where bathroom insulation wasn't prioritized during construction.

Waterproofing problems can also trap moisture within wall cavities or subflooring, creating a cycle where humidity never fully dissipates. Failing caulk around tubs and showers, or inadequate vapor barriers behind tile, allow moisture to penetrate and linger.

To address persistent humidity, start by upgrading to a properly sized, quiet exhaust fan with a timer or humidity sensor. Ensure it's vented directly outside, not into the attic. Consider adding a small dehumidifier for immediate relief while planning longer-term ventilation improvements.

For comprehensive humidity solutions including proper ventilation design and moisture control, Ottawa Bathrooms can assess your specific situation and recommend the most effective upgrades for your home.