A basement egress window is a window big enough and low enough to climb out of in an emergency, set in a well that lets you reach the yard. In Wisconsin it's the most common way to give a basement bedroom the second exit the state code asks for.
When a basement needs a second exit for a bedroom
Every basement needs at least one exit: a door to the outside or a stairway to the floor above [1]. A basement used for sleeping needs at least two, placed as far apart as practical and not reached from the same stairway [1]. The second exit can be:
- a door to the outside,
- a stairway or ramp to the floor above,
- a stairway to a garage that has an exit door other than the overhead door, or
- an egress window in each bedroom [1].
Wauwatosa's Building & Safety FAQ makes the same point for its homeowners: build a basement bedroom and you need a permit and another exit, usually an egress window [2].
Window size and sill height
The code sets these minimums for any window used for exiting [3]:
- It opens from the inside without tools or removing a sash.
- The net clear opening is at least 20 by 24 inches, nominal, in either direction.
- The lowest point of the clear opening is no more than 60 inches above the floor.
- If that point is more than 46 inches up, a permanent platform at least 20 inches wide and 9 inches deep must sit no more than 46 inches below the opening, with its top no more than 24 inches off the floor and able to hold 200 pounds.
The window well
When any part of the opening is below grade, the window needs an areaway (the well). It must be at least as wide as the window and reach at least 36 inches out from the wall. If its bottom is more than 46 inches below grade, it needs a ladder or steps, with rungs at least 12 inches wide and no more than 12 inches apart. The well also has to be built so water that gets into it doesn't enter the house [3].
Permits and plans
- Oak Creek requires a permit for any new egress window. Plans show the well depth, the window height from the floor and the well's distance from the foundation, plus a plat of survey [4]. An egress window that's part of a basement project is covered by the alteration permit [5].
- Franklin wants framing details with header and stud information, and a diagram of the room, its use and the window location [6].
- Milwaukee lists basement alterations as "Probably" needing a permit; call 414-286-8210 [7].
Cost
HomeGuide's egress guide puts the national average at $7,000 installed, with most jobs at $6,000 to $8,000 and a range of $4,000 to $12,000 [8]. Its basement remodel guide lists $3,000 to $7,000 [9], so ask what each quote includes: excavation, the foundation cut, the well, the window and interior trim. HomeGuide puts egress permits at $200 to $500 or more [8].
Request a quote for an egress window or basement bedroom.
We're a referral service, not a contractor, and independent contractors may pay us for referrals.
Sources
- Wis. Admin. Code SPS 321.03, Exits (Register November 2024 No. 827; fetched Nov 11, 2026) https://docs.legis.wisconsin.gov/code/admin_code/sps/safety_and_buildings_and_environment/320_325/321/ii/03
- City of Wauwatosa, Building & Safety, FAQ (fetched Nov 11, 2026) https://www.wauwatosa.net/government/departments/building-safety
- Wis. Admin. Code ch. SPS 321 (PDF, Register November 2024 No. 827), s. SPS 321.03(6) windows used for exiting. https://docs.legis.wisconsin.gov/document/administrativecode/ch.%20SPS%20321.pdf
- City of Oak Creek, Egress Window Permit (fetched Nov 11, 2026) https://www.oakcreekwi.gov/709/Egress-Window-Permit
- City of Oak Creek, Residential Alteration (fetched Nov 11, 2026) https://www.oakcreekwi.gov/725/Residential-Alteration
- City of Franklin, One & Two Family Addition/Alteration Permit Applications (PDF, 2026) https://www.franklinwi.gov/Files/Inspection/One-and-Two-Family-Addition-Alteration-Permit-Application-2026.pdf
- City of Milwaukee DNS, Does It Need a Permit? (fetched Nov 11, 2026) https://city.milwaukee.gov/DNS/permits/PermitChecklist
- HomeGuide, "How Much Does Egress Window Installation Cost?," byline Oct 22, 2025. https://homeguide.com/costs/egress-window-installation-cost
- HomeGuide, "How Much Does a Basement Remodel Cost? (2026)," Jennifer Carlson, Feb 6, 2026. https://homeguide.com/costs/basement-remodel-cost