Accessory Dwelling Unit (ADU) Permit in Commerce City, Colorado

Commerce City requires an accessory dwelling unit (adu) permit for: Only one ADU allowed per lot on a single-family dwelling lot; ADU cannot exceed 75% of the floor area of the principal unit or 1,000 sq ft, whichever is less; a 750 sq ft ADU is permitted regardless of the principal unit's size; Water, sanitary service, and electrical utilities shall not be separately provided to an ADU -- they are shared with the principal dwelling; The principal dwelling's address remains the same; the ADU is assigned a Unit designation by the city's GIS Department before application submittal (contact GIS@c3gov.com); Vehicular access to the ADU may not be separate from the principal dwelling's access, unless the ADU is alley-accessed and the principal dwelling is street-accessed; Detached ADU must be sited so its front wall is behind the principal building's rear wall; Maximum height: less than the principal building's height or 22 feet, whichever is less; Setbacks: front setback same as principal building; 5 ft side setback; 5 ft rear setback; side-on-street setback same as principal building; If the ADU includes a full kitchen (stovetop or oven), full bathroom, and bedroom together in the same space, specific ADU building-code rules apply, including an independent egress path that does not pass through the primary dwelling unit; Adjoining ADUs require a 1-hour fire-resistance-rated wall/floor assembly, unless interconnected smoke and CO alarms activate in both units; ADU must have a separate heating system, separate ducting, and separate climate controls, but may share the same potable water system with separate, accessible main shutoff valves; ADU must have ready occupant access to the primary dwelling's service disconnect, overcurrent devices, shutoff valves, and appliance shutoff valves. If your project isn't listed, confirm with Commerce City Building Safety Division (Community Development Department) at 303-289-3790 before starting work.

In Commerce City, the published Building Permit Fee (Table 1-A) — valuation-based is: Same valuation tiers as new residential construction (e.g., $30.41 minimum up to $7,257.12 + $4.72/$1,000 over $1,000,000). Additional published fees: Plan Review Fee — 65% of the Building Permit Fee. These are the jurisdiction's own published figures — see the fee schedule table and source citations on this page.

Commerce City's published plan-review target for an accessory dwelling unit (adu) permit is 14–14 business days.

You'll need: Address Unit Designation; Building Plans; Building Permit Application (eTRAKiT). See the required-documents checklist on this page for details on each.

Commerce City requires 4 inspection(s) for an accessory dwelling unit (adu) permit, in order: Foundation, Framing, MEP Rough-In, Final. Schedule each through Commerce City Building Safety Division (Community Development Department) (303-289-3790).

Apply through Commerce City Building Safety Division (Community Development Department) at South Platte Crossing Building, 7190 Colorado Blvd. Ste 600 (6th Floor), Commerce City, CO 80022. Phone: 303-289-3790, email: cdpermits@c3gov.com. Office hours: Monday - Friday, 8:00 a.m. - 5:00 p.m.. Official information: https://www.c3gov.com/Business-Development/Building-Permits-Inspections.

An ADU cannot exceed 75% of the principal unit's floor area or 1,000 sq ft, whichever is less. A 750 sq ft ADU is permitted regardless of the principal unit's size.

No. Water, sanitary service, and electrical utilities shall not be separately provided to an ADU -- they must be shared with the principal dwelling unit.