Accessory Dwelling Unit (ADU) Permit in Northglenn, Colorado

Northglenn requires an accessory dwelling unit (adu) permit for: ADUs are permitted in zoning districts RS-1, RS-2, RS-3, RM-1, RM-2, MN, and PD (subject to case-by-case review for PD districts containing multifamily/live-work components); ADUs are generally prohibited in multifamily dwellings or live/work units; Only one ADU allowed per property; Size limit: 750 SF for detached ADUs or ADUs added as an addition to the primary structure across all listed zone districts (RS-1/RS-2/RS-3/RM-1/RM-2/MN); ADUs located entirely within the basement of an existing single-family home may exceed 750 SF if fully contained within the primary building footprint; Height limit 20 ft across all listed zone districts (pitched/gable/hip roofs may extend up to 5 ft above the 20 ft limit if at least 70% of the roof area has a minimum 4:12 pitch); Front setback varies by zone: 30 ft (RS-1), 25 ft (RS-2), 15 ft (RS-3, RM-1, RM-2), 5 ft min/15 ft max (MN); side setback 5 ft in all listed zones; rear setback none in RS-1/RS-2/RS-3/RM-1/RM-2, 5 ft in MN (most residential properties also carry a 5 ft rear utility easement); Building coverage cap: 40% (RS-1), 60% (RS-2 through MN); rear yard structure coverage cap 30% in all listed zones; Property owner must reside in either the primary dwelling or the ADU; ADU ownership may never be legally separated from the primary residence/lot; ADUs used for short-term rentals require the property owner to reside on the property; ADUs shall not have more than one bedroom; Separate water and sewer services are NOT permitted for an ADU (must connect to the primary dwelling's systems, with specific routing rules for attached vs. detached ADUs); separate electric and gas metering IS allowed; Existing building sewer pipes may lack sufficient depth for a detached ADU — a sewage pump or ejector may be required; One off-street parking space required per ADU, only if additional parking demand is anticipated beyond what the primary residence already provides; Building permit required for all ADUs; homeowners/architects may initiate the permit but may not perform the work themselves — General Construction, Electrical, Mechanical, and Plumbing contractors must all be listed before issuance; ADUs must have independent heating and water heaters; may require 1-hour fire-rated separation if adjacent to the primary structure; radon control systems required for new ADUs (existing basement conversions may be exempt); a blower-door (air leakage) test may be required before Certificate of Occupancy; Modular, manufactured, or tiny-home ADUs must additionally meet Colorado Division of Housing (DOH) certification standards, submitted at time of city permitting; For detached ADUs, a utility plan showing the water/sewer connection to the primary dwelling is required, including the existing water meter size (contact Utility Billing at 303.450.8770 if unknown); a fixture count of all existing and proposed fixtures (primary residence plus ADU) is required per IRC Table P2903.6, converted to supply demand via Table P2903.6(1); Governed by Northglenn UDO Article 11-4, Article 11-6, and Chapter 10 of the Municipal Code. If your project isn't listed, confirm with City of Northglenn Building Division (operated under contract by SAFEbuilt) at 303.450.8745 before starting work.

In Northglenn, the published Building Permit Fee (general Valuation Chart) is: $23.50 minimum, scaling per the valuation tiers. 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.

Northglenn's published plan-review target for an accessory dwelling unit (adu) permit is 10–14 business days.

You'll need: Building Permit Application (CommunityCore); Utility Plan (detached ADUs); Fixture Count. Depending on your project, Northglenn may also ask for: Colorado Division of Housing Approval. See the required-documents checklist on this page for details on each.

Northglenn requires 5 inspection(s) for an accessory dwelling unit (adu) permit, in order: Foundation (if new construction), Framing, Rough Electrical/Plumbing/Mechanical, Blower Door Test, Final Inspection. Schedule each through City of Northglenn Building Division (operated under contract by SAFEbuilt) (303.450.8745).

Apply through City of Northglenn Building Division (operated under contract by SAFEbuilt) at 11701 Community Center Drive, Northglenn, CO 80233. Phone: 303.450.8745, email: building@northglenn.org. Office hours: Weekdays, 8:30 a.m. to 4:30 p.m., except holidays; Inspection Request Line 303.450.8748 (call before 4 p.m. for next-work-day scheduling). Official information: https://www.northglenn.org/government/departments/building/.

750 square feet for detached ADUs or ADUs added as an addition to the primary structure. ADUs built entirely within an existing single-family home's basement may exceed 750 SF if fully contained within the primary building's footprint.

No. Separate water and sewer services are not permitted for an ADU — it must connect to the primary dwelling's utility systems. Separate electric and gas metering, however, is allowed.