Check if your window meets IRC egress requirements and size the window well correctly.
Enter your window's net clear opening dimensions — the actual usable opening when the window is fully open, not the rough frame size. Enter the sill height from the finished floor, select your room type, and optionally fill in window well dimensions. Hit Calculate to get an instant IRC compliance verdict with a detailed breakdown.
Egress window requirements exist for one reason: to save lives. In a fire or emergency, a window can be the only escape route — or the only way a firefighter can enter to rescue you. The IRC (International Residential Code) Section R310 sets strict minimums that every sleeping room must meet.
Basement bedrooms are among the most common code violations found during home inspections. A too-small window can cause a sale to fall through, trigger costly remediation, or worse — trap someone during an emergency. The typical non-compliant scenario is a window that passes on area (5.7 sq ft) but fails on minimum height (24") or minimum width (20"), since both individual dimensions must be met independently.
Window wells add another layer of complexity. If your well is deeper than 44 inches, IRC requires a permanently affixed ladder or steps. Neglecting this requirement is the #2 egress defect found by home inspectors. Getting the well width and projection right also ensures the window can fully open without obstruction — a window that opens into a well wall is just as useless in an emergency as one that's too small.
The IRC R310 minimums for sleeping rooms are:
Net Clear Opening Area = Width (in) × Height (in) ÷ 144 (converts sq in to sq ft)
All three dimensional checks must pass simultaneously. A window that is 10" wide and 99" tall technically exceeds 5.7 sq ft but fails because it's under 20" wide.
For window wells: if depth exceeds 44 inches, a ladder or steps are required. The well must be wide enough that the window can fully open (typically projection ≥ window width and width ≥ 36 inches).
The net clear opening is the actual unobstructed space available when the window is in its fully open position. For a casement window this is nearly the full frame size; for a single/double-hung window it's roughly half the frame height. Measure with the window open, not the frame dimensions.
Only if the basement is used as a sleeping room or habitable space. A storage basement with no beds doesn't technically require egress windows under IRC — but having them is strongly recommended for safety, and many local codes require emergency egress in all basements regardless of use.
Yes, provided the cover can be easily opened from the inside without tools or special knowledge and can support a 750-pound load per IRC. Locking window well covers are not permitted for egress windows. Some covers have built-in hinges that allow them to swing open under body weight.
No — this is the most common misconception. You must independently meet the minimum area (5.7 sq ft), minimum clear height (24"), minimum clear width (20"), AND maximum sill height (44"). All four must pass simultaneously. Many windows pass on area but fail on one of the individual dimension limits.