Colorado ADU Laws & Rules by City (2026)

Key Colorado ADU Laws

Colorado ADU Laws

Denver has comprehensive ADU-friendly policies since 2010
Statewide efforts — HB 24-1152 expanding ADU rights
Boulder and Fort Collins have adopted progressive ADU rules
HB 24-1152 (effective June 30, 2025): subject jurisdictions must allow at least 1 ADU where single-family detached homes are allowed — a partial statewide mandate

Colorado Cities ADU Comparison

City	Max Size	Setbacks	Permit Fees	Build Cost	1BR Rent	Score
Boulder	800 sq ft (market-rate); up to 1,000 sq ft (affordable ADU program)	Confirm with Boulder Planning (reduced rear setbacks ~3 ft apply to market-rate detached ADUs near alleys)	$1,900-$3,200	$160,000-$320,000	$1,600-$2,100/mo	8/10
Colorado Springs	50% of principal dwelling or 1,250 sq ft (whichever is less); 750 sq ft max if principal < 1,500 sq ft	12 feet	$1,800-$3,000	$130,000-$260,000	$1,250-$1,700/mo	7/10
Denver	Up to 1,000 sq ft on lots over 7,000 sq ft (864 sq ft on 6,000-7,000 sq ft lots; ~650 sq ft on smaller lots) — varies by zone district	Must be within rear 35% of lot; 5 ft minimum rear setback	$500-$5,000 building permit + ~$2,055 Denver Water SDC (rising to $2,170 on Jul 1, 2026); total permit/utility typically $6K-$10K	$140,000-$280,000	$1,400-$1,900/mo	8/10

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Colorado ADU Laws & Rules (2026)

Key Colorado ADU Laws