Egress Window Size: A Beginner's Guide

Egress window size requirements are essential for safety and because of building codes. However, building codes change.

Therefore, just because your home has egress windows doesn’t mean they meet the current requirements.

In this article, we will go over the definition of an egress window, egress window size requirements, window well requirements, and more.

What is an egress window?

Simply put, an egress window is an emergency exit. If you need to get out of the house in a hurry, you exit through an egress window. The International Residential Code (IRC) states that egress window size must be big enough to allow residents to exit quickly and first responders to easily enter while carrying equipment. The IRC also says that all rooms used for sleeping, basements, and attics must have an egress window that’s easy to open from the inside without a key.

For more information, see our guide to basement egress windows.

Egress window size requirements

The IRC (see Emergency Escape and Rescue Openings, R310.2) states that egress window size must have a net clear opening of at least 5.7 square feet. If the floor is basement or ground level, the minimum net clear opening should be 5.0 square feet. The smaller egress window size requirement is because a ladder isn’t required to reach a basement or ground floor window. (When the ladder hooks onto a window, it takes up space.) If the egress window is in a basement, it must include a window well for easy escape. We will talk more about window wells below.

To be sure about egress window size requirements, it’s always best to check with your local municipality. Their requirements may differ from those of the International Residential Code. Window manufacturers also provide the net clear opening and if they meet egress window size requirements.

How many egress windows are required in a basement?

If the building is used as a residence, there must be at least one egress window in the basement. The basement egress window needs to open easily from the inside without a key.

Exterior view of an egress window in a basement bedroom.

Window well requirements

If the bottom of the egress window is below the first floor, in a basement, for example, it must have a window well. A window well is a semi-circle cutout that not only allows natural light into the basement but provides an easy escape route as well in case of emergency.

The window well must allow the egress window to fully open so that someone can pass through it to escape from the building. There are other requirements as well:

• From the window to the back of the window well should be no less than 36 inches.
• The area inside the window well should be at least 9 square feet.

These dimensions will allow residents to escape quickly and first responders carrying bulky gear to enter. Additionally, if the window well is deeper than 44 inches, there must be a permanently attached ladder.

Homeowners can cover their window wells, provided the person trying to escape can easily open them from the inside without a key. For more detailed information, see the IRC R310.2.3, the section on window wells.

If you’re thinking about remodeling your basement to turn it into a living area, check out our guide to basement drain systems.

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