5 county-level rules, plus city-specific rules for 4 cities in Arapahoe County, Colorado.
Verified from official government sources
Arapahoe County approved ADUs in unincorporated areas effective September 12, 2023, under LDC Section 3-3.2 D. Three types are permitted: internal, attached, and detached. Minimum lot size is 5,000 sq ft. Owner occupancy is required and short-term rental is prohibited.
Sheds and accessory structures in unincorporated Arapahoe County must comply with the Land Development Code dimensional standards in Table 4-1.1. Building permits are required for construction. Setback requirements vary by zone district.
Garage conversions in unincorporated Arapahoe County require building permits and must comply with the Land Development Code. Converting a garage to an ADU is permitted under Section 3-3.2 D. Off-street parking requirements must still be met.
Arapahoe County Land Development Code classifies carports as accessory structures. Permits are required. Setbacks are 5 feet side/rear in most residential zones, maximum height 16 feet, and carports count toward the 30-35% lot coverage maximum.
Arapahoe County treats foundation-built tiny homes under 400 sq ft as dwellings governed by 2018 IRC Appendix Q. Tiny homes on wheels are classified as RVs under CRS 42-1-102(61) and generally cannot serve as permanent dwellings in residential zones.
4 cities in Arapahoe County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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