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Bernalillo County, NM Accessory Structures: ADU Rules (2026)

Some Restrictions

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

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

Key Facts

Max size: 1,000 sq ft or 50% of primary home
Distance from primary home: 35-50 ft depending on lot size
Min distance from other structures: 10 feet
Approval type: By-right permissive use in R-1
Applies to: Unincorporated county only

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 New Mexico under recent ADU streamlining laws. The Bernalillo County, NM rules below cover local size, height, and setback requirements.

Summary

In unincorporated Bernalillo County's R-1 zone, a secondary dwelling unit is allowed by right if it meets setback, spacing, and size limits under the county zoning ordinance.

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

n. Secondary dwelling unit, provided that the use meets the following requirements: ... 3. The secondary dwelling unit shall: a) Meet the setbacks of the underlying zone; and b) Be located at least ten feet from any other dwelling unit or structure on the lot; and c) Be located a maximum of 35 feet from the primary dwelling unit, or 40 feet for properties half acre or greater, or 50 feet for properties 1 acre or greater; and d) Not exceed 1,000 square feet or 50 percent of the size of the primary dwelling unit, whichever is less.

Source: Bernalillo County Zoning Ordinance (Appendix A)View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 92).

Full Breakdown

The Comprehensive Zoning Ordinance permits one secondary dwelling unit per R-1 lot as a permissive use, not a discretionary permit. It must meet the underlying zone's setbacks, sit at least 10 feet from any other dwelling or structure, and sit within 35 feet of the primary home (40 feet on half-acre-plus lots, 50 feet on one-acre-plus lots). Size is capped at 1,000 square feet or 50% of the primary dwelling, whichever is smaller, and both units must connect to a wastewater system meeting the Environmental Health Code. This governs unincorporated county land only. Albuquerque, which holds most of the county's population, regulates ADUs under its own Integrated Development Ordinance, not this code.

Violations & Fines

Building a secondary dwelling unit that violates the setback, spacing, or size caps is a zoning violation; the county Zoning Administrator can require correction or removal, and an unpermitted second dwelling unit sharing a lot with an existing mobile home or accessory living quarters is barred outright under subsection B.2.n.6.

Frequently Asked Questions

Can I build a secondary dwelling unit on my R-1 lot in unincorporated Bernalillo County?

Yes, by right, if it meets the underlying zone's setbacks, sits 10+ feet from other structures, stays within 35-50 feet of the primary home, and is 1,000 sq ft or 50% of the primary home's size, whichever is less.

Does this rule apply if I live in Albuquerque?

No. Albuquerque regulates accessory dwelling units under its own Integrated Development Ordinance; the county zoning ordinance governs unincorporated land only.

Can I add a secondary dwelling unit if I already have a mobile home on the lot?

No. A secondary dwelling unit is not permitted on a lot that already has an accessory living quarters, mobile home, existing secondary dwelling unit, or second kitchen in the primary dwelling.

Sources & Official References

[1]Bernalillo County Code, App. A (Comprehensive Zoning Ordinance), § 9

Other rules in Bernalillo County

Fence Regulations: Height LimitsSome Restrictions Shed & Carport RulesSignificant Restrictions Tiny HomesSome Restrictions Noise Ordinances: Barking DogsSome Restrictions Noise Ordinances: Aircraft NoiseSome Restrictions Parking Rules: Loading ZonesLight Restrictions Parking Rules: Abandoned VehiclesSome Restrictions Fence Regulations: Retaining WallsSome Restrictions

All Bernalillo County rules

How Bernalillo County compares: Easiest Cities to Build an ADU·Compare Bernalillo County to another location·View the New Mexico accessory structures overview

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ADU Rules in Cities Across Bernalillo County

Albuquerque, NM