Egress Window Requirements: The Basics Every Homeowner Should Know

Egress windows aren't just about building codes—they're about life safety. According to the NFPA (National Fire Protection Association), bedroom windows provide a critical escape route when fire blocks interior exits.

What Is an Egress Window?

According to the International Residential Code (IRC), an egress window is:

• An operable window large enough for a person to escape through
• Located in every sleeping room and basement
• Designed to allow firefighter entry as well as occupant escape

The Minimum Requirements

According to IRC Section R310 (adopted by Idaho):

| Requirement | Minimum |
|-------------|---------|
| Clear opening area | 5.7 sq ft |
| Clear opening height | 24 inches |
| Clear opening width | 20 inches |
| Maximum sill height | 44 inches from floor |

Important: The opening must meet ALL requirements simultaneously. A window can fail even if it exceeds one dimension but falls short on another.

Where Egress Is Required

According to the IRC:

• Every bedroom (sleeping room)
• Basement habitable spaces
• Any room used for sleeping

Guest rooms, bonus rooms converted to bedrooms, and basement bedrooms all require egress.

Why These Specific Numbers

According to NFPA fire safety research:

5.7 square feet: Allows a person to fit through quickly

24" minimum height: Allows passage of shoulders

20" minimum width: Allows passage with some room to maneuver

44" maximum sill height: Low enough to climb through; accessible to children

Window Styles and Egress

According to ICC guidelines, window style affects egress capability:

| Window Style | Egress Potential |
|--------------|------------------|
| Casement | Excellent (100% of opening usable) |
| Double-hung | Good (only bottom sash counts) |
| Sliding | Good (only sliding portion counts) |
| Awning | Poor (limited opening) |
| Fixed | None (doesn't open) |

The Bottom Line

If you're replacing bedroom windows, egress compliance is mandatory. According to the Idaho Division of Building Safety, permit inspections will verify egress requirements. Non-compliant windows must be corrected.

*For complete egress information, see: [Egress Window Requirements](/guides/egress-window-requirements)*