Quick answer: An egress window contractor cuts a new opening in your foundation (or enlarges an existing one), installs a code-size window and window well, and handles drainage, the permit and the inspection. Under the International Residential Code, a basement egress opening needs at least 5 square feet of clear opening (5.7 above grade), a clear height of 24 inches, a clear width of 20 inches and a sill no higher than 44 inches. Every basement bedroom needs one.
When You Need an Egress Window
- Every basement bedroom needs its own emergency escape opening.
- Finished basements need at least one emergency escape opening.
- A basement room listed as a bedroom when you sell must have egress to count as one, which affects your home’s value.
- Renting out a basement or building an ADU there requires code egress.
If you are finishing a basement, plan egress windows from the start. They are much easier to install before the drywall goes up.
Egress Window Code Requirements (IRC R310)
Colorado cities adopt the International Residential Code, sometimes with local changes. The core egress rules are:
- Clear opening: at least 5.7 square feet, or 5 square feet for grade-floor and below-grade openings.
- Clear height: at least 24 inches.
- Clear width: at least 20 inches.
- Sill height: no more than 44 inches above the finished floor.
- Window well: at least 9 square feet of floor area and at least 36 inches out from the wall and 36 inches wide.
- Ladder or steps: required when the well is deeper than 44 inches, permanently attached.
- Operation: it must open from inside without keys or tools. Well covers must open the same way.
The clear opening is what matters, not the window’s overall size. Casement windows give the most clear opening for their size. Sliders need a much bigger unit to pass. Always check with your local building department, since some cities add their own requirements.
What the Install Includes
- Permit and layout. Choosing a location away from utilities, downspouts and structural loads, and pulling the permit.
- Utility locate. Calling Colorado 811 before digging.
- Excavation outside the wall for the window well.
- Cutting the foundation with a concrete saw. Widening an opening in a poured wall may need a new header or an engineer’s letter.
- Drainage. Gravel in the well bottom tied to your foundation drain, a sump or daylight so the well does not fill with water.
- Window install with waterproofing and sealing around the cut opening.
- Window well, ladder and cover, then backfill and grading away from the house.
- Interior finish: framing, insulation, drywall returns and trim, plus the final inspection.
What Drives the Cost
- Wall type: poured concrete takes more cutting than block, and thicker walls take longer.
- Depth: deeper basements need deeper wells, ladders and more digging.
- Access: decks, patios, AC units and tight side yards make excavation slower.
- Existing window: enlarging an existing opening is usually less work than a brand-new cut.
- Well type: galvanized steel, composite and terraced landscape wells vary widely in price.
- Drainage: tying into an existing drain is simpler than adding a new drain line.
- Interior finishing if the basement is already finished.
Questions to Ask an Egress Window Contractor
- Will you pull the permit and be there for the inspection?
- How will the window well drain?
- Who handles the interior finish around the new opening?
- Is the window well cover openable from inside without tools?
- Do you carry liability insurance, and are you licensed in my city?
One more tip: cutting into a foundation can change how radon moves into your house. Retest for radon after the work is done.
We install egress windows as part of basement finishes across the Front Range. See our egress window installation in Denver, basement finishing in Fort Collins and window replacement pages.
Frequently Asked Questions
What size does a basement egress window have to be?
Under the IRC, a below-grade egress opening needs at least 5 square feet of clear opening, a clear height of 24 inches and a clear width of 20 inches, with the sill no more than 44 inches above the floor. Check your local code for changes.
Do I need a permit for an egress window in Colorado?
Yes, in most Colorado cities and counties. Cutting a new opening in a foundation is structural work, and the building department inspects the window, well and opening.
Does every basement bedroom need an egress window?
Yes. Under the IRC, every sleeping room needs its own emergency escape opening, including bedrooms in basements.
How deep can a window well be without a ladder?
A window well deeper than 44 inches needs a permanently attached ladder or steps under the IRC.
What kind of window works best for egress?
Casement windows give the most clear opening for their size, so they usually meet egress rules in the smallest window. Sliders need a larger unit to pass.
Planning a Basement Finish or Egress Window?
We handle the permit, the cut, the well, drainage and the interior finish under one contract. Josh Brooks Construction and Renovation Inc. is a licensed general contractor based in Longmont with 30 years in construction, serving 46+ Front Range cities. Call 720-828-7997 or text 720-453-5095.
Licensed. Local. Not a storm chaser.
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Get an Egress Window Quote
Ready to add an egress window? See our egress window installation page, or our basement finishing page if the window is part of a full basement finish. Call 720-828-7997 or text 720-453-5095 for a free estimate.
