Building codes dictate that an egress window or door be large enough to allow people easy exit and to allow rescue crews easy entrance in case of a fire or other emergency. The International Residential Code requires:
- 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.
- The window sill—the bottom edge of the window—cannot be higher than 44 inches from the basement floor.
Egress below ground
Adding an egress window for a basement completely below grade means cutting a hole in your basement’s concrete or concrete block wall. This takes some muscle and skill, so don’t try to do it yourself. It’s a noisy, messy job, but straightforward for a skilled professional, who also will install the window and trim.
Egress above/at grade
If your yard slopes, your new egress window could be installed completely above grade.
If your foundation walls barely peek above the soil line, you’ll have to dig down and install a window well. (Mark all water, sewer, cable, gas, and electrical lines before you dig.)
Wells must be big enough to allow a person to climb easily out the window and away from the house. 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.
A ladder must be installed in deep wells so occupants can climb out.
Egress from your wallet
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 to $800.
If you plan to install an egress window and well yourself, plan to spend about $500 to $900 for rental of a concrete saw to cut through your basement walls, window, and window well kit.
Before beginning DIY work, ask a structural engineer to examine walls to determine if they need reinforcing headers over the new window to bear the load of the house above. Expect to pay $150 for a consultation.
Rich Binsacca is the author of 12 books on home-related topics, is a contributing editor for Builder and EcoHome magazines, and has written articles for Remodeling, Home, and Architectural Record magazines.