Expanding or Modifying Nonconforming Structures in Mesa, Arizona

In the City of Mesa, a legal nonconforming building may be maintained and repaired provided structural repairs do not exceed 50% of the building's construction value. While general expansions that increase the degree of nonconformity are prohibited, the City of Mesa Zoning Ordinance allows legal nonconforming single-family or duplex residences to be enlarged by up to 50% of their floor area with an approved Special Use Permit.

Understanding Nonconformity in Mesa

According to the City of Mesa Zoning Ordinance, a "nonconformity" exists when a building, structure, or land use was legally established but no longer complies with current standards such as height, setbacks, floor area, or parking [Section 11-36-2]. These "legal nonconforming" entities are permitted to continue but are subject to specific restrictions regarding their expansion or modification.

Maintenance and Structural Repairs

The City of Mesa allows the continued use and maintenance of nonconforming structures. However, there are strict financial thresholds for structural repairs.

Type of Work	Requirement/Limit
Routine Maintenance	Allowed to keep the structure in safe condition [Section 11-36-5].
Structural Repairs	Allowed if the cost does not exceed 50% of the construction value (excluding foundation) [Section 11-36-5].
Reconstruction (Damage < 50%)	May be restored or rebuilt to its previous configuration [Section 11-36-6].
Reconstruction (Damage > 50%)	Must comply with all current City of Mesa zoning regulations, unless a Special Use Permit is granted [Section 11-36-6].

Rules for Expansion and Alteration

The City of Mesa Zoning Ordinance generally prohibits the expansion of nonconforming uses into other structures or onto other lots [Section 11-36-3]. However, certain physical alterations or enlargements to the structure itself may be approved by the Zoning Administrator.

Administrative Approval Criteria

The Zoning Administrator may approve alterations to a nonconforming structure if the project meets the following conditions [Section 11-36-7]:

The project does not further reduce any existing nonconforming yard (setback).
The project does not exceed applicable City of Mesa building height limits.
The project does not further reduce existing nonconforming Lot Coverage or Floor Area Ratio (FAR) requirements.
Any increase in required off-street parking is provided for the new addition.

Residential Exceptions (The 50% Rule)

The City of Mesa provides a significant exception for residential properties. A legal, nonconforming single-family residence or duplex may be enlarged by up to 50% of its existing Floor Area without being required to provide additional parking spaces, provided that:

The number of dwelling units on the lot does not increase.
The applicant obtains an approved Special Use Permit (SUP) [Section 11-36-7].

Secondary Units on Nonconforming Lots

If a property in the City of Mesa contains a single-family residence that is nonconforming only because it lacks sufficient parking, a second unit may be developed on the same lot. This is permitted as long as the second unit itself meets all current City of Mesa requirements, including its own required parking [Section 11-36-7].

Abandonment of Nonconforming Status

Property owners in the City of Mesa should be aware that if a nonconforming use is discontinued or the building is vacated for a continuous period of one year or more, the nonconforming status is lost. Any subsequent use or structure on that site must comply entirely with the current City of Mesa Zoning Ordinance [Section 11-36-4].

Sections Cited

Section 11-36-2: Establishment of Legal Nonconforming Uses, Structures, and Lots
Section 11-36-3: Expansion of Nonconforming Uses
Section 11-36-4: Abandonment of Nonconforming Uses
Section 11-36-5: Continuation and Maintenance of Nonconforming Uses or Structures
Section 11-36-6: Damaged or Partially Destroyed Structures
Section 11-36-7: Alterations and Enlargements to Nonconforming Structures