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Weld County, CO Accessory Structures: ADU Rules (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

ADU rules in Weld County, CO, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

ADUs per legal lot: One maximum
On a lot with a duplex: Not permitted
Lot must be: Verified legal lot
Governing code: Weld County Code § 23-4-600
Inside Greeley/Evans: City code applies instead

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in Colorado under recent ADU streamlining laws. The Weld County, CO rules below cover local size, height, and setback requirements.

Summary

In unincorporated Weld County, one accessory dwelling unit is allowed per legal lot where Article III permits it. The ADU may be attached, detached, or inside a single-family dwelling, but is barred on a lot with a duplex. Greeley and Evans set their own city ADU rules.

City-specific rules exist: Greeley has its own adu rules rules that differ from Weld County's county-level regulations. If you live in Greeley, check the city-specific page instead.

An ADU may be attached to, detached from, or contained within a SINGLE-FAMILY DWELLING. An ADU is not permissible on a LOT with a DUPLEX. No LOT shall contain more than one (1) ADU. No ADU shall be permitted unless the Department of Planning Services has determined the LOT to be a LEGAL LOT.

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Charter and County Code: Supplement 95).

Full Breakdown

Weld County Code Chapter 23 (Zoning) governs ADUs on unincorporated land, which covers most of this large agricultural county. Under Section 23-4-600, before a building permit issues an ADU must sit on a lot the Department of Planning Services has verified as a legal lot, no lot may hold more than one ADU, and an ADU cannot go on a lot that already has a duplex. The ADU must meet all bulk requirements (setback, offset, height) of the applicable zone district. Residents inside the cities of Greeley or Evans follow those cities' own municipal codes, not the county code. Confirm zoning eligibility with Weld County Planning Services before building.

Violations & Fines

Building an ADU without meeting Section 23-4-600 or without a zoning and building permit is a zoning violation enforced by Weld County Code Compliance under Chapter 23, Article X, with orders to correct, permit, or remove.

Frequently Asked Questions

How many ADUs can I build in unincorporated Weld County?

One per legal lot, where Article III of Chapter 23 permits it. The ADU may be attached, detached, or inside the single-family home, but is not allowed on a lot that already has a duplex.

Do Weld County ADU rules apply inside Greeley?

No. Weld County Code Chapter 23 governs unincorporated land. Homes inside Greeley or Evans follow those cities' own municipal zoning codes. Confirm ADU rules with the relevant city planning department.

Sources & Official References

Other rules in Weld County

Fence Regulations: Height LimitsSome Restrictions Shed & Carport RulesSome Restrictions Garage ConversionsSome Restrictions ADU Impact FeesSome Restrictions Tiny HomesSome Restrictions Noise Ordinances: Barking DogsSome Restrictions Noise Ordinances: Decibel LimitsSome Restrictions Noise Ordinances: Vehicle NoiseSome Restrictions Parking Rules: Loading ZonesSome Restrictions Parking Rules: EV ChargingFew Restrictions

All Weld County rules

How Weld County compares: Easiest Cities to Build an ADU·Compare Weld County to another location·View the Colorado accessory structures overview

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ADU Rules in Cities Across Weld County

Greeley, CO