What is an egress window?

A finished egress window installed for a basement bedroom in downtown Middleton

When planning a remodeling project, we tend to focus on design elements like fixtures, color schemes, and layout. In basement remodeling, one feature tends to surprise homeowners with its impact on safety, legality, and home value: the egress window. If you’re finishing a basement into a living space such as a bedroom, an egress window is more than just an optional upgrade, it’s a mandatory building code requirement.

An egress window is a window specifically designed and sized to allow people to exit a building safely in an emergency—most notably, a fire. The term “egress” simply means a way out. In addition to providing an exit route, egress windows also allow firefighters to enter the home if necessary.

Unlike standard basement hopper windows, which are often small and at ground level, egress windows must meet strict size and accessibility guidelines to ensure that someone can climb out without difficulty. This is especially important in a basement, where the usual exit routes (stairs and doors) may be blocked during an emergency.

Why do egress windows matter? Safety, legal requirements, and home value

1) Egress windows save lives. Basements often have limited exits, and a fire on the main floor can trap occupants. An egress window provides an alternate escape route, giving residents a way of escaping.

2) Any room used as a sleeping area must have its own egress window. You cannot label a room as a bedroom for legal or resale purposes without one. Here in Dane County, a basement room cannot legally be counted as a bedroom unless it has an egress window in addition to a closet. If you're remodeling a basement with the intention of adding a bedroom, you'll be required to install both.

3) If an emergency occurs, certain homeowner’s insurance claims may be denied if you undergo a basement remodel without the proper egress requirements. Installing an egress window ensures compliance with policy rules and reduces potential liability.

4) Homebuyers value legal bedrooms, natural light, safety features, and expanded usable square footage. Adding an egress window during a basement finishing allows for the creation of a legal bedroom, which is certain to increase your home’s value.

5) Egress windows bring in more natural light and ventilation, making the basement less prone to mold, mildew, and poor air quality—issues that can lead to long-term health concerns.

What are the building code requirements for egress windows?

Window Opening Size:

• Must have a minimum net clear opening of 5.7 square feet (5.0 square feet on the ground floor).

• Must have a minimum opening height of 24 inches.

• Must have a minimum opening width of 20 inches. Both width and height minimums must still add up to the required 5.7 square feet of clear opening—meeting one dimension alone isn’t enough. And it never hurts to go bigger if you can accommodate a larger window opening when finishing your basement.

• Must be operable from the inside without keys, tools, or special knowledge.

Window Sill Height:

The bottom of the window opening cannot be more than 44 inches above the floor. If it's higher, a permanently installed ladder or step must be added inside the bedroom for an occupant to climb up onto the sill and exit the window.

Window Well Dimensions:

Egress windows require a window well on the exterior. A small excavator is used to dig the hole to accommodate a prefabricated window well enclosure. Then a concrete saw is used to cut a window opening into your home's foundation. A compliant window well must:

• Provide 9 square feet of floor area.

• Have a minimum horizontal projection and width of 36 x 36 inches.

• Include a permanent ladder or steps if the well is deeper than 44 inches.

• Any cover over the window well must be easily opened without tools, even from inside.

View inside the window well - note the exit steps built into the back and the gravel for drainage

How does finishing your basement with an egress window increase your home's value?

Installing an egress window during a basement remodel is one of the highest ROI upgrades a homeowner can make.

1) You can add a legal bedroom. A bedroom is one of the most valuable additions to a home’s listing. Real estate professionals estimate that adding a legal bedroom can increase a home’s market value by 10–20%, depending on location.

2) You gain code-compliant additional square footage. Buyers may avoid homes with questionable or unofficial remodels. An egress window legitimizes your basement as real living space and makes the home easier to sell. Additional livable space always increases appeal—whether it becomes a home office, gym, bedroom, entertainment area, or guest suite.

3) You gain natural light. Egress windows brighten basements dramatically, making them feel larger, cleaner, and more welcoming.

4) You gain potential rental income. Adding an egress window may open the door to legal rental opportunities. A basement apartment can produce significant extra income and offset the cost of finishing your basement. If you’re creating a legal rental unit, building codes will require at least one or more egress windows depending on the layout. This applies to accessory dwelling units (ADUs), mother-in-law suites, or Airbnb-style rentals.

In summary...

An egress window is one of the most important elements to consider when planning a basement remodel. When installed properly and to building code, it will transform your dark unfinished basement into a bright, inviting living space. It is also a mandatory safety feature when adding a basement bedroom, which can significantly increase the overall value of your home. Even if no bedroom is added, installing an egress window when finishing your basement is still a smart way to increase the usefulness, aesthetics, and longevity of your remodeling project.