Egress Window Cost and Size Requirements

Updated October 2026 · 4 public sources cited

If you're adding a basement bedroom, you almost certainly need an egress window. Here's what one costs installed and the code dimensions inspectors check.

Egress window size requirements

Most U.S. cities adopt the International Residential Code (IRC), sometimes with local amendments. Under the IRC, an emergency escape and rescue opening generally needs:

• At least 5.7 square feet of net clear opening (5.0 square feet for openings at grade floor level);
• At least 24 inches of net clear opening height;
• At least 20 inches of net clear opening width;
• A sill no more than 44 inches above the finished floor;
• Operation from inside without keys, tools or special knowledge.

Note that 24 × 20 inches is only 3.3 square feet. To reach 5.7 square feet, a window that's 24 inches high must be much wider, which is why sliders and casements are popular for egress. Measure the clear opening when the window is open, not the frame size.

Window well rules

When the sill is below grade, the IRC generally requires a window well:

• At least 9 square feet of horizontal area, with at least 36 inches of projection and width;
• A permanently attached ladder or steps when the well is deeper than 44 inches;
• Room for the window to open fully;
• Drainage at the bottom to keep water away from the foundation.

Covers are allowed if they can be opened from inside without tools or unusual force. Local rules vary. Des Moines, for example, publishes its own basement egress window policy.²

What goes into the cost

• Excavation outside for the well, by hand or machine.
• Cutting the foundation: concrete or block, with a saw sized for the wall, plus a header if needed.
• The window itself, sized for egress.
• The well: steel, composite or a tiered/landscape design, plus a ladder if required.
• Drainage: gravel and a drain tied to the footing drain or a sump where possible.
• Interior finish: framing, trim and drywall returns.
• Permit and inspection fees.

Prices climb with poured concrete walls, rock or tight access for equipment, landscape or deck removal, and drainage problems. HomeGuide puts typical jobs at $6,000 to $8,000 and the overall range at about $4,000 to $12,000 or more.¹

Permits

Cutting a new opening in a foundation is structural work, and nearly every building department requires a permit for a new or enlarged egress window. Minneapolis³ and Colorado Springs⁴ both cover egress in their basement finish requirements. Local guides: Denver, Colorado Springs, Minneapolis and Des Moines.

When you need one

• Any new basement bedroom (sleeping room) needs an emergency escape and rescue opening.
• Many codes also require one in a basement with habitable space when it's newly finished, though exceptions exist. Check with your building department.
• An existing small window often can't be counted as egress unless it meets the size rules.

Planning a full finish? See our basement finishing cost guide.

General information summarized from the public sources listed below. It isn't professional, medical or legal advice. A licensed professional who inspects your home can tell you what it needs.