R-20 Residential
Honolulu's most restrictive standard residential designation. Minimum 20,000 sf lots with a 30% coverage maximum — the tightest in the residential series. Common in hillside and estate areas. The combination of large lots, steep topography, and the 30% coverage limit creates a complex planning envelope.
Common locations: Tantalus, upper Nuuanu, portions of Manoa hillside, Diamond Head estates, and other large-lot areas.
Development standards
| Standard | Requirement |
|---|---|
| Minimum lot area | 20,000 sf |
| Front yard | 15 ft min |
| Rear yard | 10 ft min |
| Interior side yard | 5 ft min |
| Street-side yard | 10 ft min |
| Max lot coverage | 30% |
| Max building height | 30 ft |
| FAR limit | None |
On steep lots, grade variations affect both height measurement and lot coverage calculations. Retaining walls and site walls may or may not count toward coverage depending on their configuration.
Source: ROH §21-3.10-5 (R-20 district standards)
Sample calculation
Common DPP plan-check violations
Key exceptions and reliefs
Enter your lot dimensions and proposed footprint — instant lot coverage, envelope, and FAR check for R-20.
Upload your drawings for a full citation-anchored compliance report covering R-20 zoning + IBC in ~30 min.
Development standards are based on ROH Chapter 21 as of May 2026. Verify all values against the current DPP-adopted code before relying on them. Overlay districts (SMA, flood zone, historic), special area requirements, and neighborhood-specific provisions may impose additional standards not reflected here.