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Castle Rock, CO Accessory Structures: ADU Rules (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified July 2026

ADU rules in Castle Rock, CO, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

ADUs per lot: One maximum
Governing code: Chapter 17.61
Deed restriction: Required before permit
Separate utility taps: Not allowed
Separate sale: Prohibited

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in Colorado under recent ADU streamlining laws. The Castle Rock, CO rules below cover local size, height, and setback requirements.

Summary

Castle Rock allows accessory dwelling units, but no more than one ADU per lot. Before a building permit issues, the owner must record a deed restriction barring rental of both the primary home and the ADU at the same time, and no separate water/sewer taps are permitted.

No more than one (1) ADU may be created or maintained on a single lot. Prior to issuance of a building permit for an ADU, the property owner shall record a deed restriction... prohibiting the concurrent renting of both the Primary Dwelling Unit and the Accessory Dwelling Unit.

View official code

Full Breakdown

Chapter 17.61 of the Town Zoning Code governs ADUs. One ADU may be created or maintained on a single lot. An ADU may not be subdivided or conveyed into separate ownership from the primary dwelling. If an addition creates a new outside entrance, only one entrance may be visible from the addressed street; any additional entrance must be on the side or rear. No separate water or sewer taps are allowed, and the primary-dwelling account holder must certify responsibility for the ADU's utility charges. Apply through the Town's eTRAKiT Development Portal via Development Services.

Violations & Fines

Building without a permit or without the required recorded deed restriction is a zoning-code violation subject to Town Code Compliance enforcement, stop-work, and correction orders.

Frequently Asked Questions

Can I rent both my house and the ADU at once?

No. A recorded deed restriction prohibits concurrently renting both the primary dwelling and the ADU on the same lot.

Can the ADU have its own water meter?

No. No separate water or sewer taps are allowed; the primary account holder is responsible for the ADU's utility charges.

Sources & Official References

Other rules in Castle Rock

Parking Rules: Overnight ParkingSome Restrictions Parking Rules: Curb Color RulesSome Restrictions Parking Rules: Loading ZonesSome Restrictions Parking Rules: Commercial & Oversized VehiclesSome Restrictions Parking Rules: Driveway RulesSome Restrictions Parking Rules: Abandoned VehiclesSome Restrictions

All Castle Rock rules

How Castle Rock compares: Easiest Cities to Build an ADU·Compare Castle Rock to another location·View the Colorado accessory structures overview

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