Add an Egress Window to Your Finished Basement

For safety, a remodeled basement living area needs an egress window that meets residential building codes. Here’s what you need to know.

An egress window like this one provides natural light and fresh air to lower-level living areas while providing safe, code-compliant emergency egress. Image: Bilco’s ScapeWEL® Window Well System

When converting a basement into a living area, your safety is a primary consideration. That’s why building codes specify that a finished basement must have an emergency egress—an egress window or door large enough to allow people to easily exit the space, and for rescue crews to gain access in case of fire or other emergency. Besides gaining peace of mind, you’ll also benefit from more natural light and ventilation, adding to the comfort and value of your below-grade oasis.

Adding an egress window usually means cutting a large enough hole in your basement wall. If your basement has solid concrete or concrete block walls, the job will require the services of a skilled mason or basement remodeling specialist. It’s a noisy, messy job, but the process is relatively straightforward for a skilled professional, as is the placement of the window and any finish work involved.

If you have a sloping yard, it may be that your new egress window can be installed completely above grade. If your foundation walls barely peek above the soil line, however, you’ll have to excavate down and provide a window well. The size of a window well also is determined by building codes to allow a person to easily climb out of the window and exit the house. In case of a deep well, a ladder must be fixed to the well so that an occupant can safely climb out.

If your egress window requires a window well, be sure to call first to have all buried utilities marked so that you won’t run into any electrical, gas, cable, water, or sewer lines.

Code compliance

According to the most current residential building codes, if your basement retreat includes one or more “sleeping rooms,” such as a dedicated spare bedroom, each of those rooms must have an egress window. In addition, a single egress window must be furnished for “common-use” areas, such as a TV room, game room, or home office. Occasional-use spaces, such as bathrooms, laundry rooms, and utility areas, don’t need emergency egress.

Code also specifies that the clear opening of a basement egress window should be at least 20 inches wide and at least 24 inches high, and achieve a minimum area of 5.7 sq. ft.—the smallest opening an average adult male can reasonably crawl through. In addition, the window sill—the bottom edge of the window—cannot be higher than 44 inches from the basement floor.

When shopping for an egress window, make sure to calculate size correctly. Do the math and you’ll find that a 20-inch-wide window actually needs to be 41 inches tall to comply with the minimum 5.7 square-foot requirement for an egress window. Similarly, a 24-inch-tall window must be at least 34.2 inches wide.
 
Most full-height basements (defined as having at least 7-foot ceilings) are built with windows on at least one wall to allow daylight and perhaps some measure of passive ventilation into the basement. But it’s unlikely that those windows meet the current code for egress. Even if they are large enough, they probably aren’t set low enough to meet the maximum 44-inch sill height requirement.

Types of windows

There are several standard window types that comply with the egress code. An insulated casement window is ideal because it is hinged along its side edges and swings outward to allow easy egress. You may install double-hung windows, but be aware that code requirements for minimum size will apply to the lower, operable half of the window—meaning the window will end up being quite tall and any window well will be extra deep—adding expense.

Sliders—windows that move from side-to-side—also may end up being quite large to accommodate codes, but because they operate in a horizontal position, a window well will not have to be excessively deep. Expect to pay $150 to $350 for a vinyl, vinyl-clad wood, or all-wood frame window.

Building a window well

Installing a code-compliant egress window with its sill only 44 inches from the finished floor likely means an excavation outside your foundation walls to create a window well. By code, the total “clear” floor area inside of the well must be at least 9 sq. ft, with at least a 3-foot area between the window and the far edge of the well opening.

If the window well is more than 44 inches deep, it must have a permanently attached ladder or steps to enable safe egress. The ladder or steps can project into the well no more than 6 inches without having to extend the code-required clear area of the well. As such, most ladders are welded to the metal shell that encloses the well.

For the safety of your family when you are gardening or playing outside, building codes also allow a metal grate, typically hinged, to be placed across the window well opening to protect pets and people from falling in. Still, you must be able to remove or open the grate from inside or outside the window well without special tools in the event of an emergency.

To facilitate drainage of the well, the construction may include installation of a perforated pipe covered over with washed gravel to carry excess water away from the well, window, and foundation wall.

Because a window well is a prominent feature when viewed from inside the basement room, it’s a good idea to incorporate some simple landscaping features, such as potted plants. Make sure that any design features won’t interfere with safe egress.

Construction costs

Hiring a licensed contractor to cut your basement wall, build a window well, and install a window will cost $2,500 to $5,000, depending on the complexity of the project and the depth of the well. Adding a grate and providing drainage adds another $500-$800.

Some basement remodeling contractors specialize in building egress windows using manufactured kits that include all the necessary components. Ask to see finished samples of their work before signing a contract to ensure you’ll be satisfied with the look of the kit.

If you plan to tackle the installation of an egress window as a DIY project, you’ll save money. Be forewarned—cutting through concrete walls is a major task. Plan to spend about $500-$900 for all materials, including the rental of a concrete saw to cut through your basement walls, a window, and a window well kit.

Before you begin any DIY work, seek the advice of a structural engineer to examine your walls and advise you about any concerns, such as installing a header over your window to accept the weight of floor joists and a load-bearing wall above. Expect to pay $150 for a consultation.

Fortunately, there is nothing in the code preventing you from adding plantings around the well to shield it from view and better integrate it into your overall landscape design, as long as it doesn’t hinder the ability to easily access the well and window.