Make your finished basement safe, permit-ready, and resale-smart
If you’re planning a basement bedroom in Colorado—whether you’re in Denver, Fort Collins, Colorado Springs, or a smaller Front Range community—egress windows are one of the first items that inspectors look at. The basics come from the International Residential Code (IRC), but local adoption dates and amendments can vary by jurisdiction. This guide summarizes the most common 2026-era expectations, explains the measurements that matter, and shows how to avoid the rework that can derail a basement finishing timeline.
What “egress” means in a Colorado basement remodel
In residential code language, an Emergency Escape and Rescue Opening (often shortened to “egress window”) is an operable window (or door) that provides a safe way out during an emergency. Basements and every sleeping room typically need at least one compliant emergency escape and rescue opening.
For homeowners, the key point is simple: if you want to market a basement space as a legal bedroom, the opening size, sill height, and (if below grade) the window well must meet code for your city/county at the time of permit.
2026 baseline measurements: the numbers that usually drive pass/fail
Many Colorado jurisdictions continue to use IRC-based standards that match the familiar requirements below (always confirm locally—especially if you’re in Denver or a home-rule municipality).
| Requirement | Typical IRC-based minimum | Why it matters |
| Net clear opening area | 5.7 sq ft (grade-floor openings: 5.0 sq ft) | Ensures a person and rescuers can pass through. |
| Net clear width | 20 inches | The opening must be wide enough under normal operation. |
| Net clear height | 24 inches | The open portion (not the glass size) must meet the minimum. |
| Max sill height from finished floor | 44 inches (many jurisdictions); some code versions show 48 inches—verify locally | Too high = hard to access in an emergency. |
| Operation | Must open from inside without keys/tools/special knowledge | Security bars and covers must release easily from inside. |
Important: “Net clear opening” is the actual open space after the window is opened—not the rough opening, not the frame size, and not the glass size. Casement windows often provide more net clear area than sliders at the same rough opening.
Window wells (below grade): sizing, ladder rules, and drainage
If the bottom of the clear opening is below exterior grade, an area well/window well is typically required. Common IRC-based rules include:
| Window well requirement | Typical IRC-based minimum | Practical note for homeowners |
| Horizontal area | 9 sq ft | Bigger often feels safer and helps with drainage/maintenance access. |
| Projection + width | 36 inches minimum each | The window must be able to open fully into the well. |
| Ladder/steps trigger | Well depth > 44 inches requires a permanent ladder or steps | Plan this early—ladder placement can affect the usable clear area. |
| Ladder basics | Inside width ≥ 12″, projection ≥ 3″, rung spacing ≤ 18″ o.c.; ladder/steps can encroach up to 6″ | Avoid bulky ladder systems that reduce the “feel” of the exit path. |
Drainage is where many basement egress projects fail later
Even when the window and well meet the dimensional requirements, poor drainage can create standing water, freeze/thaw issues, and long-term foundation risk. Some jurisdictions explicitly reference tying well drainage into the foundation drainage system or another approved method.
Step-by-step: how to plan a compliant basement bedroom egress window
1) Identify which room is the “bedroom”
If you’re adding a bedroom, code will treat it differently than a rec room or gym. Plan egress, smoke/CO alarms, and HVAC with that label in mind.
2) Measure “net clear,” not “window size”
Ask your contractor (or window supplier) for the manufacturer’s net-clear specs for the exact model and size you’re considering—especially if it’s a slider.
3) Confirm sill height early
Basement finishing often adds subfloor + finished flooring. That can raise the finished floor and accidentally push the sill height out of compliance if you didn’t plan for it.
4) Design the well for real-world use
Minimums can pass inspection, but homeowners often prefer a larger well for easier exit, better light, and safer ladder placement—especially in snow-prone parts of Colorado.
5) Watch decks, porches, and exterior obstructions
If the egress opening is under a deck or porch, the code can require a clear path to a yard/court. Don’t assume a tight gap will be acceptable.
6) Pull permits for structural cuts
Enlarging a basement window often means cutting a foundation wall opening. Some Colorado jurisdictions note that engineered design/inspection may be required for foundation wall cuts.
Homeowner tip: If your goal is a fast, permit-ready basement finish, build the egress plan before you lock the floorplan. Moving a bedroom wall is usually easier than moving an egress location after framing.
Quick “Did you know?” facts (egress edition)
- A “big-looking” window can still fail.
- Sliders often have smaller net-clear openings than casements with similar rough openings. Always confirm net-clear specs.
- 44 inches is a common trigger for two different issues.
- A typical max sill height is 44 inches, and a typical well-depth threshold for requiring a ladder/steps is also 44 inches.
- Denver’s code timing matters right now.
Denver adopted the 2025 Denver Building and Fire Codes incorporating the 2024 I-Codes, effective December 31, 2025—and projects submitted on or before that date may be able to use either the 2022 or 2025 Denver codes.
Local angle: Denver + statewide Colorado reality in 2026
Colorado is a “local control” state for many building-code decisions. That means your egress window plan can be impacted by where your house is—not just what the IRC says.
Denver homeowners (2026 permitting)
As of December 31, 2025, Denver’s updated 2025 Building and Fire Codes are effective and incorporate the 2024 I-Codes (with energy code handled separately). If you’re starting a basement remodel in early 2026, confirm which code set your permit will be reviewed under.
Front Range cities can shift at different times
Example: Fort Collins notes new codes (2024 International Codes) effective April 1, 2026. If your remodel is near that transition, a submission date could determine which rules apply.
Counties may adopt updates on their own schedule
Mesa County, for instance, approved an ordinance adopting updated building codes with an effective date of September 1, 2025. This is why “Colorado-wide” advice should always be paired with local verification.
Bottom line for Colorado homeowners: Start with the IRC-based dimensions, then confirm your jurisdiction’s adopted code year and amendments before ordering windows or cutting a foundation wall.
Need a permit-ready basement plan?
ElkStone Basements specializes exclusively in basement finishing and remodeling—helping Colorado homeowners align design goals (bedrooms, theaters, wet bars, rec rooms) with practical build requirements like egress, layout, and inspection readiness.
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FAQ: Colorado egress window requirements (2026)
Many jurisdictions require at least one emergency escape and rescue opening in basements, and each sleeping room typically needs one as well. Requirements can vary by local adoption and amendments, so confirm with your building department for your address.
A widely used IRC-based standard is 5.7 sq ft net clear opening (or 5.0 sq ft for grade-floor openings), plus minimum net clear dimensions of 20″ wide and 24″ high.
You’ll see both numbers depending on which code edition (and local amendments) your jurisdiction is using. Many IRC-based local publications in Colorado reference 44 inches for maximum sill height, while other references show 48 inches in certain contexts/editions. Treat this as “verify locally before you build.”
A typical IRC-based rule is that if the window well depth is more than 44 inches, you need a permanently affixed ladder or steps that can be used with the window fully open.
They can. Denver adopted the 2025 Denver Building and Fire Codes incorporating the 2024 I-Codes, effective December 31, 2025, with specific transition guidance based on submission timing. Always confirm the code set tied to your permit application.
Ready to transform your space with a beautiful, functional basement? ElkStone Basements serves homeowners throughout Colorado and Utah with expert design and build services tailored to your needs. Don’t wait to unlock the potential in your home — get started today! Visit to schedule your consultation and take the first step toward your dream basement.
Glossary (plain-English)
Net clear opening: The open space you can actually pass through when the window is fully opened (not the frame or glass size).
Emergency Escape and Rescue Opening (EERO): The code term for a window/door that provides an emergency exit path from a basement or bedroom.
Window well / area well: The exterior recess that creates clearance for a below-grade egress window to open and provide an exit route.
Home-rule municipality: A Colorado city with more local authority to adopt/modify codes. Home-rule areas can differ from neighboring jurisdictions.
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