Avondale, AZ Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Freeboard
- 1 foot above base flood elevation (regulatory flood elevation)
- AO zone alternative
- 2 feet above highest adjacent grade if no depth specified
- Certification required
- Registered engineer or surveyor, verified by city inspector
- Manufactured homes
- Frame/lowest appliance at or above RFE
Summary
Avondale requires new construction and substantial improvements in a flood hazard area to have their lowest floor elevated to or above the regulatory flood elevation, which the code sets one foot above base flood elevation. That one-foot freeboard applies to residential structures, manufactured homes and, with floodproofing, non-residential buildings alike.
"Regulatory flood elevation (RFE)." An elevation one (1) foot above the base flood elevation for a watercourse for which the base flood elevation has been determined and shall be determined by the criteria developed by the Director of the Arizona Department of Water Resources for all other watercourses.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 38 Update 1).
Full Breakdown
Sec. 8-5 defines 'regulatory flood elevation (RFE)' as an elevation one foot above the base flood elevation for a watercourse where the base flood elevation has been determined, or as set by criteria from the Director of the Arizona Department of Water Resources for other watercourses. Sec. 8-40(c)(1) requires residential new construction or substantial improvement to have its lowest floor, including any basement, elevated to or above the regulatory flood elevation in zones AE, AH and A1-30, or elevated at least two feet above the highest adjacent grade in an AO zone with no depth number specified.
That elevation must be certified by a registered professional engineer or surveyor and verified by the city's building inspector before it is accepted. Sec. 8-44(b)(1) applies the same one-foot-above-base-flood-elevation freeboard standard to manufactured homes, requiring the bottom of the structural frame or lowest attached appliance, whichever is lower, to sit at or above the regulatory flood elevation. Non-residential structures under sec. 8-40(c)(2) may instead be floodproofed watertight up to that same elevation, with the design certified by a registered engineer or architect and filed with the floodplain administrator.
Violations & Fines
A structure built below the required regulatory flood elevation without an engineer's certification is presumed in violation under sec. 8-5's definition of 'violation' until documentation of compliance is provided. Sec. 8-23 makes unauthorized development in a delineated floodplain a class 2 misdemeanor, and other violations of the elevation standards are civil infractions carrying a penalty up to the maximum class 2 misdemeanor fine. A variance to build below the regulatory flood elevation triggers a written notice under sec. 8-51(e) that flood insurance premiums can rise as high as $25.00 per $100.00 of coverage.
Frequently Asked Questions
How much freeboard does Avondale require above base flood elevation?
Who certifies that a new Avondale home meets the flood elevation requirement?
Does a manufactured home in Avondale need the same freeboard?
Sources & Official References
Other rules in Avondale
Compare Avondale to another location·View the Arizona environmental rules overview
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Flood Elevation Requirements in Nearby Cities
How other cities in Maricopa County handle flood elevation requirements.