Retaining Walls: Denver vs Phoenix
How do retaining walls rules compare between Denver, CO and Phoenix, AZ?
Denver and Phoenix have similar restriction levels.
Denver, CO
Denver County
Denver requires a building permit for retaining walls over 4 feet (measured from bottom of footing to top of wall) per DBC 105.2. Engineered drawings required. Lower walls with surcharge also need permits.
View full Denver rules →Phoenix, AZ
Maricopa County
Phoenix requires building permits for retaining walls over 3 feet in height. Combinations of retaining walls and fences always require structural design calculations. Combined wall-fence structures exceeding 9 feet need zoning approval. Walls 3 feet or less are exempt from permits unless on hillside lots.
View full Phoenix rules →Key Facts Comparison
| Fact | Denver | Phoenix |
|---|---|---|
| Permit Threshold | Over 4 feet | Over 3 ft requires permit |
| Engineering | Licensed PE stamp required | - |
| Surcharge Rule | Permit at any height | - |
| Drainage | Required on plans | - |
| No Permit Needed | - | 3 ft or less (non-hillside) |
| Combo Walls | - | Always require structural calcs |
| Zoning Approval | - | Required if combo exceeds 9 ft |
| Hillside Lots | - | All retaining walls need permits |
Highlighted rows indicate differences between cities.
Denver FAQ
Who enforces retaining walls rules in Denver County?
Denver County's code enforcement division is responsible for fences ordinances. You can report violations or request information through the Denver County government website or by calling the main municipal line.
What are typical penalties for violating retaining walls rules?
Most Denver County fences violations start with a written warning followed by escalating civil fines for repeat offenses. Specific dollar amounts and any criminal-misdemeanor exposure depend on the section of code; consult Denver County's municipal code or staff for the current penalty schedule.
Phoenix FAQ
Do I need a permit for a retaining wall in Phoenix?
Unsurcharged retaining walls 3 feet or less do not require a permit (unless on a hillside lot). Walls over 3 feet require a building permit with structural design calculations. Combined retaining wall/fence structures always require structural calculations.
How is retaining wall height measured?
Height is measured from the bottom of the footing to the top of the wall, not from the top of the soil. A railing or view fence on top of a retaining wall is permitted up to 40 inches if needed for pedestrian safety.
Compare other topics
See how Denver and Phoenix compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool