Arapahoe County, CO Accessory Structures: ADU Rules (2026)
ADU rules in Arapahoe County, CO, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Permit review point
- At building permit application (§ 3-3.2.D.21)
- Deed restriction required
- Before certificate of occupancy (§ 3-3.2.D.19)
- Principal dwelling requirement
- Must exist or be built concurrently
- Recording office
- Arapahoe County Clerk and Recorder
- Water/septic proof needed
- For both principal dwelling and ADU
Summary
Arapahoe County reviews ADU compliance at the building permit stage, and requires a recorded deed restriction before it will issue a certificate of occupancy. The principal dwelling must already exist, or be built at the same time as the ADU.
19. Deed Restriction Before obtaining a certificate of occupancy for an ADU, the property owner of record shall record a deed restriction on the lot or parcel proposed for an ADU with the Arapahoe County Clerk and Recorder... 21. Process Compliance with these ADU regulations will be reviewed at the time of building permit application.
Full Breakdown
20 requires that "a single-family detached dwelling must exist on the lot or parcel as a principal dwelling or be constructed concurrently with an ADU," and a certificate of occupancy for the ADU won't issue until one has already been issued for the principal dwelling. 21 ("Process") states plainly that "compliance with these ADU regulations will be reviewed at the time of building permit application": there is no separate ADU-specific permit application beyond the building permit. 19 requires the owner of record to record a deed restriction with the Arapahoe County Clerk and Recorder, in a form acceptable to the Director of Public Works and Development or the County Attorney, that bars selling or subdividing the ADU separately from the principal dwelling, locks the ADU to its approved size, requires strict compliance with the Code, ties the certificate of occupancy to continued owner-occupancy of either unit, and binds successors in ownership.
The deed restriction only lapses once the ADU is removed and the owner submits a written request, at which point the Director of Public Works and Development or County Attorney records the release. Utility approvals are also part of the permit record: if the principal dwelling is on a public water or wastewater system, on a private well, or on a septic system, the owner must supply evidence of approval from the relevant provider, the Colorado Division of Water Resources, or the Arapahoe County Public Health Department, respectively, covering both the principal dwelling and the ADU.
Violations & Fines
Occupying an ADU before a certificate of occupancy has issued for the principal dwelling, or before the deed restriction is recorded, is a Land Development Code violation. The Public Works and Development Department enforces compliance under LDC Chapter 6, and a certificate of occupancy for the ADU stays valid only so long as an owner of record continues to reside in the principal dwelling or the ADU as the deed restriction requires.
Frequently Asked Questions
Do I need a separate permit for an ADU in Arapahoe County?
What does the ADU deed restriction require?
Can I build an ADU before the main house exists?
Sources & Official References
Other rules in Arapahoe County
How Arapahoe County compares: Easiest Cities to Build an ADU·Compare Arapahoe County to another location·View the Colorado accessory structures overview
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