Egress Windows for a Basement ADU in Denver: Code, and Costs

Why Egress Windows Are Non-Negotiable for Denver Basement ADUs

Denver's accessory dwelling unit (ADU) boom has transformed how homeowners think about their basements. What was once storage space or a rec room is now potential rental income—but only if it meets code. And the single most important requirement? A compliant egress window.

If you're planning a basement ADU in the Denver metro area, an egress window isn't optional. It's a life-safety requirement mandated by the Colorado Building Code and enforced by the City and County of Denver. This window serves as an emergency exit in case of fire or other emergencies, and inspectors won't sign off on your finished basement bedroom without one—or more, depending on square footage.

At Affordable Egress Co., we've been helping Denver homeowners meet these requirements since 1999. We've watched the ADU trend grow, and we've installed thousands of compliant egress windows across the Denver metro and Front Range. Here's what you need to know before breaking ground on your basement ADU project.

Denver Building Code Requirements for Basement Egress Windows

The Colorado Building Code (which Denver adopts and enforces) requires that every bedroom—including basement bedrooms in an ADU—have at least one emergency exit. For basements, that exit must be an egress window or door.

Here are the minimum specifications:

• Net clear opening: At least 5.7 square feet (or 5.0 sq ft if the room is under 70 sq ft)
• Minimum width: 20 inches
• Minimum height: 24 inches
• Sill height: No more than 44 inches from the floor (this is why window wells are typically required)
• Window well dimensions: Typically 40"–48" wide × 36"–48" deep, depending on your basement depth and soil conditions

Denver's soil composition—mostly clay and sand mix with varying density—affects how deep your window well needs to be and what kind of foundation reinforcement is necessary. Our team assesses your specific soil and foundation conditions during the free estimate to ensure your installation will pass final inspection.

Installation Process, Code Requirements, and Pricing

We coordinate all project prep before we break ground. Denver has specific requirements for egress window work — we know them all.

Here's what to expect:

1. application: Your contractor (or you, if owner-building) submits plans showing the window location, well dimensions, and structural details.
2. Pre-installation inspection: Denver building officials may inspect the planned location before work begins.
3. Installation: Most of our egress installations are completed in a single day, including concrete cutting, window well installation, and the window itself. Weather and soil conditions can add a day in rare cases.
4. Final inspection: An inspector verifies the window meets code—opening size, sill height, well depth, and structural support.

Front Range weather and Denver's elevation (5,280 feet) also factor into timeline. Spring and fall are ideal installation windows. Summer heat can affect concrete curing, while winter conditions complicate excavation. We factor these into scheduling and always provide a realistic timeline upfront.

Egress Window Costs for Denver ADU Basements

What does a compliant egress window cost in Denver? Most homeowners see installed costs between $2,500 and $4,500, depending on:

• Basement depth and soil conditions
• Existing foundation structure
• Window well material (powder-coated steel, polycarbonate, or aluminum)
• Whether the basement has existing egress that needs upgrading
• Location (easier access = lower labor)

We offer a free estimate so you know the exact cost before committing. We'll measure your basement, assess soil and foundation conditions, and provide a detailed quote that includes concrete labor, and all inspections.

Choose a Local Expert for Your Denver ADU Egress Window

Your basement ADU project is an investment in your Denver home's value and your family's long-term flexibility. Building it right means choosing a contractor who knows Denver code, understands local soil and weather challenges, and has the track record to prove it.

Since 1999, Affordable Egress Co. has been the trusted name for egress window installation across Denver and the Front Range. We specialize in basement bedrooms and ADUs, we complete most installations in one day, and we stand behind every project with certified, inspected work.

Ready to move forward with your basement ADU? Request your free estimate today and let's make sure your egress window—and your entire project—meets Denver code and inspires confidence for years to come.