Do I need tempered glass for the window next to my bathtub or is that just a recommendation?

Yes, tempered glass is required by the Ontario Building Code for windows within 600mm (about 2 feet) of a bathtub or shower. This isn't just a recommendation - it's a mandatory safety requirement to prevent serious injury from glass breakage in wet, slippery bathroom conditions.

The Ontario Building Code specifically requires safety glass (tempered or laminated) in what's called "hazardous locations." Bathrooms qualify because of the combination of water, soap, and the potential for slips and falls. When someone falls against regular glass near a tub, it can shatter into dangerous shards. Tempered glass breaks into small, relatively harmless pieces, while laminated glass holds together even when cracked.

In Ottawa's climate, bathroom windows also face unique challenges from temperature fluctuations and humidity. The temperature difference between a hot shower and cold winter air can stress regular glass. Quality tempered glass handles these thermal stresses much better and provides better long-term durability.

Most modern bathroom windows come standard with tempered glass when installed by experienced professionals, as they're familiar with code requirements. However, if you're replacing an older window yourself or working with an installer who does not raise it, you need to specifically request tempered glass. The glass should be marked with a small etched stamp indicating it meets safety standards.

For your window replacement project, ensure your installer knows about the proximity to your bathtub. City of Ottawa requirements may vary - confirm with your installer, but the OBC requirement is clear. A professional installer will automatically specify tempered glass for this location and ensure proper installation to handle bathroom moisture and temperature changes.