Hawaii: basement moisture and foundation risk by county
5 counties, ranked by our combined index. Highest combined risk is Honolulu County (50), lowest is Hawaii County (36). The worst soil for foundation cracks specifically is in Honolulu County.
Where in Hawaii the ground is worse
Every county in the state, coloured by the soil values below. Click a county to open its report; switch what the colour means with the buttons. The pattern is geology, not administration — risk stops at the edge of a physiographic region, not at a county line.
- Low (0–27)
- Moderate (28–49)
- Elevated (50–74)
- High (75–100)
County boundaries: US Census TIGER (public domain), simplified for display. Colours are our index from USDA SSURGO fields where loaded, otherwise from our regional model — each county page states which. How the index is calculated.
| County | Index | Moisture | Cracks | Water table | Region |
|---|---|---|---|---|---|
| Honolulu County | 50 | 35 | 75 | 46 | Hawaiian volcanic soils |
| Maui County | 46 | 36 | 60 | 46 | Hawaiian volcanic soils |
| Kauai County | 45 | 36 | 56 | 46 | Hawaiian volcanic soils |
| Kalawao County | 40 | 33 | 44 | 46 | Hawaiian volcanic soils |
| Hawaii County | 36 | 33 | 45 | 30 | Hawaiian volcanic soils |
Values from USDA NRCS SSURGO where available, otherwise our regional model — each county page states which. Methodology.
The physiographic regions inside Hawaii
State lines are political; soil follows geology. These are the distinct ground types inside Hawaii and why each behaves the way it does.
Hawaiian volcanic soils
Volcanic soils behave unlike anything on the mainland: some hold enormous water yet drain well, while leeward Vertisols are strongly expansive. Basements are essentially absent; the moisture problem is post-and-pier crawlspaces and slab-on-grade in a climate that never dries out.
5 counties: Hawaii County, Honolulu County, Kalawao County, Kauai County, Maui County
Page data updated