Colorado ADU Laws & Rules (2026)

Compare ADU zoning rules across 3 Colorado cities. Average ADU score: 7.7/10.

ModerateDenver Leading

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
  • No statewide mandate yet, but momentum building

Colorado Cities ADU Comparison

CityMax SizeSetbacksPermit FeesBuild Cost1BR RentScore
Boulder 800 sq ft (market-rate); 1,000 sq ft (affordable ADU program) 10 feet $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 864 sq ft Must be within rear 35% of lot; 5 ft minimum rear setback $1,600-$2,700 $140,000-$280,000 $1,400-$1,900/mo 8/10

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