Retaining Walls: Mililani Town vs Pearl City
How do retaining walls rules compare between Mililani Town, HI and Pearl City, HI?
Mililani Town and Pearl City have similar restriction levels.
Mililani Town, HI
Honolulu County
Mililani Town retaining walls follow ROH Sec. 21-4.40 rules and HOA review. Fill-retaining walls in required yards cannot exceed 6 feet, and terraced walls are measured in combination.
View full Mililani Town rules →Pearl City, HI
Honolulu County
Pearl City retaining walls on the Pearl City Highlands and Manana hillsides fall under ROH 21-4.40, capping fill-bearing walls in required yards at 6 feet and combining terraced heights.
View full Pearl City rules →Key Facts Comparison
| Fact | Mililani Town | Pearl City |
|---|---|---|
| - | - | |
| Yard max height | - | 6 feet |
| Terraced rule | - | Heights combined |
| Code section | - | ROH 21-4.40 |
| Drainage review | - | Chapter 14 |
Highlighted rows indicate differences between cities.
Mililani Town FAQ
Do planter walls count as retaining walls?
If they hold back soil, yes; decorative low planters that don't retain earth are typically not regulated under 21-4.40.
Is HOA approval needed for a 24-inch garden wall?
Usually yes. Even ROH-exempt walls typically still need HOA architectural review in Mililani before construction.
Pearl City FAQ
How tall can a Pearl City retaining wall be?
Walls with fill in a required yard cap at 6 feet under ROH 21-4.40. Terraced walls are measured as combined height, and engineering review is required above the 30-inch permit threshold on hillside lots.
Do hillside walls need extra review?
Yes. Pearl City Highlands and Manana hillside sites typically require geotechnical and drainage review, engineered drawings, and Chapter 14 grading coordination alongside the 21-4.40 retaining wall rules.
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