Castle Rock basement finish permits and egress rules

A plain-English summary of the official rules for finishing a basement in Castle Rock, CO, current as of October 25, 2026. Always confirm with the building department before you start.

Who issues your permit

Inside Castle Rock Town limits: the Town of Castle Rock Development Services Building Division, through its eTRAKiT portal¹.
Unincorporated Douglas County: the Douglas County Building Division².
Not sure? The Town says to look up your address on Douglas County Maps, open Assessment Details, and check the Building Permit Authority listed in the Account Summary¹.

Castle Rock: permit basics

Basement finishes require a permit¹.
Contractors must be licensed and registered with the Town's Building Division; you can verify registration in eTRAKiT¹. Plumbers and electricians also need state licenses¹.
Homeowners can pull a permit only for their own primary residence and must submit a Home-Owner Affidavit¹.
For new permit submittals the Town uses the 2024 International Residential Code, 2021 International Energy Conservation Code and 2026 National Electrical Code, with local amendments that took effect June 30, 2026³.
Questions about submittals go to the Building Counter at 720-733-3527 or buildingcounter@crgov.com⁴.

What the plans must show

The entire basement, with all room dimensions and the intended use of each room⁴.
Furnace, water heater and stairs⁴.
All windows and window wells, with egress window and well sizes⁴.
Total finished and unfinished square footage, plus the address and owner on each page⁴.

Emergency egress requirements

Castle Rock requires emergency egress in all basement bedrooms, and in unfinished basements regardless of when the house was built⁴. Allowed options are an escape window or door straight to the outside (walk-out), an escape window into a window well, or a door to a bulkhead enclosure⁴.

Escape windows

Clear opening of at least 5.7 sq. ft.⁴
Clear openable height of at least 24 inches and width of at least 20 inches⁴.
Sill no more than 44 inches above the finished floor⁴.
Operable from inside without keys, tools or special knowledge⁴.

Window wells and ladders

Where the sill is below grade, a window well of at least 9 sq. ft., with at least 36 inches of projection and width, that lets the window open fully. Covers must open without a key or tool⁴.
Wells deeper than 44 inches need a permanently attached ladder or steps: at least 12 inches wide, rungs no more than 18 inches apart, bottom rung no more than 18 inches above the well floor⁴.
New openings cut into existing basement walls need a stamped structural engineered plan⁴.

Other Castle Rock basement rules

Habitable rooms: at least 70 sq. ft. and 7 feet in any direction; ceilings at least 7 feet (6'-8" in bathrooms and laundry rooms); hallways at least 36 inches wide⁴.
Floating walls: non-bearing slab walls must allow 3 inches of movement because of expansive soils⁴.
Smoke alarms in each bedroom, outside sleeping areas and on each floor, hardwired with battery backup and interconnected⁴.
Carbon monoxide alarms near bedrooms when permitted work is done in homes with an attached garage or fuel-fired appliances⁴.
Frost line depth: the Town's amended design criteria table sets a 36-inch minimum footing depth below finish grade⁵.

Unincorporated Douglas County

A permit is needed when any walls are built or electricity is added to the basement².
A complete application normally takes 7 to 10 business days; you need the permit in hand before starting work².
Over-the-counter plan review for basement finishes runs weekdays 8 a.m. to noon and can often produce a same-day permit⁶.
Homes on a septic system need a Douglas County Health Department approval letter to add a basement bedroom; homes with fire sprinklers need fire district approval of the basement sprinkler design².

Want a contractor to handle the permit?

Call (720) 918-0175 or request a quote. We pass your request to a local basement contractor.

Sources

Town of Castle Rock, Homeowners Building Permits. Accessed October 25, 2026.
Douglas County Building Division, Basements & Remodels. Accessed October 25, 2026.
Town of Castle Rock, Adopted Building Codes. Accessed October 25, 2026.
Town of Castle Rock, Residential Basement Finish Guide (revised 6/25/2026). Accessed October 25, 2026.
Town of Castle Rock, Ordinance No. 2026-017 (amended IRC Table R301.2(1)). Accessed October 25, 2026.
Douglas County Building Division, Over the Counter Plan Review. Accessed October 25, 2026.