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Castle Rock has some of the largest single-family lots in the Denver metro and HOA-governed communities that now must allow ADUs under Colorado law. Here’s what that means for your property.
Castle Rock’s large lots, relatively newer housing stock, and growing population make it an emerging ADU market in Douglas County. The town has updated its code to comply with HB 24-1152, enabling ADU construction on single-family lots through administrative approval.
Castle Rock has numerous HOA-governed communities. Under HB 24-1152, these HOAs cannot ban ADU construction. They can require exterior materials, roof pitch, and colors to match the primary home — but they cannot deny your project outright. Architectural review is standard and understanding what your HOA requires before designing saves significant time and money.
Detached Backyard Cottages ($200K–$400K): Castle Rock’s large lots are among the best in the metro for rear detached construction. These produce the highest long-term ROI and are most compatible with HOA design review.
Garage Conversions ($50K–$145K): Three and four-car garages common in Castle Rock subdivisions offer efficient conversion opportunities while maintaining parking — often the path of least resistance through HOA review.
Basement ADUs ($40K–$115K): Many Castle Rock homes have unfinished basements with good ceiling heights. Walk-out configurations on sloped lots are particularly well-suited for independent entrances.
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