Emergency egress codes are critical to basement safety, yet misconceptions about window size, placement, and compliance with local building codes persist, leading to unsafe conditions that put lives at risk. To clarify confusion, we spoke with Glenn Mathewson, a building code educator and founder of Building Code College, to break down what basement egress requirements really mean.
The Bedroom Dilemma
One gray area in basement egress requirements is defining what constitutes a bedroom. The International Residential Code (IRC) mandates that every sleeping room must have an emergency escape and rescue opening (EERO), commonly referred to as an egress window or door. However, as Mathewson points out, the code does not explicitly define what a bedroom is.
“This has been a century-old question,” he says, one that dates back to the London Building Acts of 1859. “The definition of a sleeping room was based on the probability that someone might sleep there. That’s still the case today,” he adds. “Some building departments say if it’s labeled a craft room, it’s a craft room. Others say, ‘If it looks like a bedroom, it’s a bedroom.’”
Because of this ambiguity, homeowners seeking permits sometimes attempt to skirt the code by calling a basement room a “sewing room” or “bonus room,” eliminating the need for a rescue opening. Contractors hired for basement renovations should know the regulations and stand by them.
“Do what’s right and put in an escape opening,” Mathewson advises.
Egress vs. Emergency Escape and Rescue Openings
A common misconception is that these windows are purely for egress — an exit point during an emergency.
“It’s not just about getting out — it’s also about rescue,” he says. “A firefighter needs to be able to enter and remove someone who is unconscious or injured.”
Remember: It’s called an emergency escape AND rescue opening. That’s why the IRC has strict size requirements to ensure accessibility:
- Minimum width: 20 inches
- Minimum height: 24 inches
- Minimum clear opening: 5.7 square feet
- Maximum sill height: 44 inches from the floor
New Builds vs. Existing Basements
The IRC makes clear distinction between new construction and existing basement renovations regarding emergency escape and rescue openings.
In new builds, the IRC mandates that every basement, finished or unfinished, must have at least one emergency escape and rescue opening. If the basement includes bedrooms, each bedroom must have its own compliant EERO. The reasoning behind this is straightforward: an unfinished basement might still be used for sleeping — whether for guests, slumber parties, or temporary sleeping arrangements.
For existing basements, the 2018 and 2021 IRC updates introduced a provision that allows reduced-size emergency escape and rescue openings when replacing an existing basement window. This recognizes the financial and structural burden of cutting into a foundation to enlarge a window opening. However, this exception does not apply in new construction or when adding new sleeping rooms to a previously unfinished basement — those situations still require fully compliant EEROs.
A caveat: Some local jurisdictions reject this reduced-size exception outright and stick with the original full-size requirements. As a precaution, pros are advised to default to the most recent IRC updates, Mathewson advises.
Ultimately, the code ensures that no one gets trapped in a basement with no way out. As Mathewson puts it: “Not all codes are created equal, but when it comes to life safety, this is a code not to mess with.”
BILCO egress window systems not only comply with IRC 2021 building code requirements for emergency egress but also add natural daylight and ventilation to basement rooms. Learn more.
