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Johnson City, Texas
Inside Johnson City's city limits, shrink-swell clay limits houses without basements on 51% of mapped land, the highest of 3 cities in Blanco County. A shallow water table limits basements on 0%.
That clay share is above Blanco County's 28%. FEMA's flood data list no flood losses since 2016 in ZIP code 78636 overlapping the city. Of its 968 homes, 33% were built before 1980; the median dates from 1993.
Data as of October 13, 2026 · sources · in Blanco County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 1 overlapping ZIP
of homes built before 1980
Foundation repair in Johnson City
Foundation repair in Johnson City: shrink-swell clay limits slab homes on 51% of Johnson City's mapped land, more than in 58% of Texas cities.
About 600 of Johnson City's 968 homes are detached houses.
| Who designs the repair | The ASCE Texas Section's repair guidelines say a Texas-licensed engineer should evaluate the foundation and design the repair (2022 guidelines) |
| Prices | Cost guide ranges compared |
Soil under Johnson City city limits
| Expansive clay (limits slab homes) | 51.4% |
| High water table (limits basements) | 0.0% |
| Septic fields very limited | 85.5% |
| Clay swell (LEP, by area) | 8.5% |
| High-swell land (LEP 6%+) | 49.1% |
| Mapped soil | 1,260 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Tarpley | 16% | n/a |
| Bolar | 13% | n/a |
| Krum | 12% | n/a |
| Anhalt | 12% | n/a |
| Hensley | 9% | n/a |
| Purves | 8% | 40% |
What the numbers mean here
Clay swell averages a linear extensibility of 8.5% by land area here, and 49% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 51% of the mapped land.
Clay shrinks as it dries: 19.9% of Blanco County is in drought on the latest map, and 51% of Johnson City's mapped land has shrink-swell clay.
USDA rates 86% of the land very limited for septic absorption fields.
Drought in Blanco County
19.9% of Blanco County is in drought (D1 or worse) on the October 13, 2026 map. County detail.
Flood losses by ZIP code
FEMA flood records since 2016 in the ZIP codes that overlap Johnson City. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 78636 | 100% | 0 | $0 |
Homes in Johnson City
| Housing units | 968 |
| Median year built | 1993 |
| Built before 1980 | 33% |
| Built 2000 or later | 41% |
| Owner-occupied | 59% |
| Median value, owner-occupied | $452,000 |
| Single-family detached | 61% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Round Mountain | 9 mi | 31% | 0% |
| Blanco | 12 mi | 28% | 0% |
| Horseshoe Bay | 19 mi | 10% | 0% |
| Double Horn | 19 mi | 70% | 0% |
| Dripping Springs | 19 mi | 12% | 0% |
| Cottonwood Shores | 20 mi | 20% | 0% |
| Meadowlakes | 21 mi | 64% | 0% |
| Marble Falls | 21 mi | 44% | under 1% |
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · Census ACS 2020-2024. Methods · Data status