Egress window requirements
The rules come from section R310 (R310.1, R310.2.1-R310.2.3, R310.4.1) of the International Residential Code as states and cities adopt it. Below is the wording in published government copies, with the edition each copy states.
An emergency escape and rescue opening (an egress window) is a window or door that lets people get out of a bedroom or basement in a fire, and lets firefighters get in. The code sets a minimum clear opening area, a minimum clear height and width, and a maximum height of the sill above the floor. Window wells outside below-grade openings have their own size rules and, when deep, need a ladder or steps.
These rules matter most when you finish a basement, add a bedroom, or replace bedroom windows: a new window that is smaller or has a higher sill than the code allows can fail inspection. Measure the clear opening with the window fully open, not the rough opening or the glass.
The International Residential Code (IRC) is a model code. It is law only where a state or city adopts it, usually with changes, so the wording below shows how the model reads in published government copies, not the rule where you live.
Galveston, TX
2021 IRC
- 5.7 square feet.
R310.2.1 Minimum size. Emergency escape and rescue openings shall have a net clear opening of not less than 5.7 square feet (0.530 m2).
1 - 5 square feet.
Exception: The minimum net clear opening for grade floor emergency escape and rescue openings shall be 5 square feet (0.465 m2).
1 - 24 inches.
The minimum net clear opening height dimension shall be 24 inches (610 mm).
1 - 20 inches.
The minimum net clear opening width dimension shall be 20 inches (508 mm).
1 - 44 inches.
R310.2.3 Maximum height from floor. Emergency escape and rescue openings shall have the bottom of the clear opening not greater than 44 inches (1118 mm) above the floor.
1
Boulder County, CO
2021 IRC
Basements and every sleeping room shall have at least one operable emergency escape and rescue opening.
2- 5.7 square feet.
Emergency escape and rescue openings shall have a net clear opening area of not less than 5.7 square feet. Grade floor openings shall have a minimum net clear opening of 5 square feet.
2 - 24 inches.
The minimum net clear openable height dimension shall be 24 inches (610 mm). The minimum net clear openable width dimension shall be 20 inches (508 mm).
2 - 44 inches.
Emergency escape and rescue openings shall have the bottom of the clear opening not greater than 44 inches above the floor.
2 - 9 square feet.
The horizontal area of the area well shall be not less than 9 square feet (0.9 m2), with a horizontal projection and width of not less than 36 inches (914 mm).
2
Boise, ID
handout dated March 2022
- 5.7 square feet.
Emergency escape and rescue openings shall have a net clear opening of not less than 5.7 square feet (0.0530 m2).
3 - 44 inches.
…it shall have a sill height of not more than 44 inches (1118mm) above the floor…
3
Duluth, MN
Minnesota Residential Code (state-amended IRC)
- 5.7 square feet.
R310.2.1 Minimum opening area: All emergency escape and rescue openings shall have a minimum net clear opening of 5.7 square feet.
4 - 5 square feet.
Exception: Grade floor openings shall have a minimum net clear opening of 5 square feet.
4
Sources
- Windows and Sliding Glass Door ComplianceCity of Galveston, TX, Building DepartmentChecked November 7, 2026
- Emergency Escape and Rescue Openings - B10Boulder County, CO, Community Planning & PermittingChecked November 7, 2026
- IRC Code Handout #438 Emergency Escape & Rescue OpeningsCity of Boise, ID, Planning & Development ServicesPublished March 2022Checked November 7, 2026
- Residential Emergency Escape and Rescue Openings (Doc 213)City of Duluth, MN, Construction Services & Inspections DivisionChecked November 7, 2026