Retaining Walls: Kailua vs Mililani Town
How do retaining walls rules compare between Kailua, HI and Mililani Town, HI?
Kailua and Mililani Town have similar restriction levels.
Kailua, HI
Honolulu County
Retaining walls in Kailua follow ROH Sec. 21-4.40, which caps fill-retention walls within required yards at 6 feet. Terraced walls count toward combined height totals, and most walls over 30 inches require engineering.
View full Kailua rules →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 →Key Facts Comparison
| Fact | Kailua | Mililani Town |
|---|---|---|
| - | - |
Highlighted rows indicate differences between cities.
Kailua FAQ
Can I build a 5-foot retaining wall in my side yard?
Yes, up to 6 feet within required yards under ROH 21-4.40, but you will likely need a permit and engineering over 30 inches.
What about two stacked 4-foot walls?
Terraced walls are typically measured together, so two closely spaced 4-foot walls may be treated as an 8-foot wall exceeding the cap.
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.
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