Colorado ADU permit requirements
Last reviewed: June 20, 2026
Quick answer
Permitting an accessory dwelling unit (ADU) in Colorado means pulling a building permit from the local authority that issues it. Colorado has a statewide ADU law that sets baseline standards local agencies must follow. ArchPermit tracks 14 source-cited requirements (11 required, the rest conditional) for this jurisdiction. These requirements were last reviewed June 20, 2026; confirm the exact forms and fees with the local permitting authority.
Colorado has a statewide ADU law. This baseline reflects that law plus the universal new-dwelling deliverables. Your local city or county still administers the permit and may add its own forms and fees — confirm the exact checklist with them.
Colorado's HB24-1152 (2024, effective June 30, 2025) requires 'subject jurisdictions' to allow one ADU by administrative approval where single-unit detached dwellings are allowed, and bars owner-occupancy and most added-parking mandates. Colorado has no statewide building code; jurisdictions that adopt one meet a 2021 IECC energy floor.
- Adopted building code compliancerequired
The ADU must comply with the residential building code adopted by the local jurisdiction — confirm the edition with the AHJ.
source · reviewed 2026-06-20 - Building cross-sectionsrequired
Cross-sections through the structure showing ceiling heights, wall/roof assemblies, insulation, and fire/sound-rated assemblies where required.
source · reviewed 2026-06-20 - Egress & life-safetyrequired
Emergency escape and rescue openings (egress windows), smoke and carbon-monoxide alarms, and required exits per the adopted residential code.
source · reviewed 2026-06-20 - Energy code compliancerequired
Energy-code compliance documentation for the conditioned space. Colorado: 2021 IECC minimum (jurisdictions adopting/updating a code 2023–2026).
source · reviewed 2026-06-20 - Exterior elevationsrequired
Elevations of each affected building face showing height, exterior materials, and openings; existing vs. proposed where exterior changes occur.
source · reviewed 2026-06-20 - Floor plansrequired
Dimensioned floor plans of the ADU (and affected areas of the primary dwelling) showing rooms, uses, door/window locations, egress, and fixture/equipment locations.
source · reviewed 2026-06-20 - Foundation planrequired
Foundation plan with footing/stem-wall sizes and details (or a cited site-specific design), per the adopted residential code.
source · reviewed 2026-06-20 - Framing / structural plansrequired
Floor, wall, and roof framing showing member sizes, spans, spacing, connections, and lateral bracing; structural calculations where the framing is non-conventional.
source · reviewed 2026-06-20 - Local zoning / setback compliancerequiredverify locally
Compliance with the local jurisdiction's zoning: permitted use, setbacks, height, lot coverage, and any ADU-specific standards. These are set locally — confirm with the permitting agency.
source · reviewed 2026-06-20 - Mechanical / plumbing / electricalrequired
HVAC, plumbing fixtures and lines, and electrical (panels, circuits, outlets, lighting, smoke/CO alarms) for the new unit.
source · reviewed 2026-06-20 - Site / plot plan (to scale)required
Scaled site plan showing property lines, setbacks, existing structures, the proposed ADU footprint with dimensions to property lines, driveways/parking, and utility locations.
source · reviewed 2026-06-20 - Administrative (ministerial) ADU approvalconditionalverify locally
Subject jurisdictions must allow one ADU on single-unit detached lots via administrative approval, not discretionary hearings.
source · reviewed 2026-06-20 - Limits on added parking mandatesconditionalverify locally
Subject jurisdictions generally may not require additional off-street parking for an ADU.
source · reviewed 2026-06-20 - No owner-occupancy requirementconditionalverify locally
Subject jurisdictions may not impose owner-occupancy on the ADU or primary dwelling.
source · reviewed 2026-06-20