Frostline.info

Frost line depth in Bexar County, Texas

Frost reaches about 4 inches in typical soil across Bexar County. Codes in this climate commonly set footing depth at 12 inches (code minimum).

Shallow frost
Estimated frost depth
4″
typical silt/loam soil
Typical code footing depth
12″ minimum
rule of thumb for this climate
Design freezing index
19
°F-days, 100-year winter
ZIP codes covered
73
#216 of 255 counties in TX (1 = deepest)
4″ 0″12″24″36″ ground frozen
Est. frost (typical soil) Typical code footing depth Clay–sand range

Frost depth by soil type

Soil typeEst. frost depth
Sand / gravel (drains well)5″
Silt / loam (typical yard soil)4″
Clay (holds water)4″

County average. Methodology.

Verify before you dig. These are climate-based estimates. The legally required frost depth is the figure your building department publishes in its IRC Table R301.2 (climatic and geographic design criteria). Call the Bexar County building or permitting office in Texas and call 811 before digging.

Frost depth by ZIP code in Bexar County

ZIPCityEst. frostCode range
78002Atascosa4″12″ minimum
78015Boerne5″12–18″
78023Helotes5″12–18″
78073Von Ormy4″12″ minimum
78109Converse4″12″ minimum
78112Elmendorf4″12″ minimum
78148Universal City5″12–18″
78150Jbsa Randolph5″12–18″
78152Saint Hedwig5″12–18″
78201San Antonio4″12″ minimum
78202San Antonio4″12″ minimum
78203San Antonio4″12″ minimum
78204San Antonio4″12″ minimum
78205San Antonio4″12″ minimum
78206San Antonio4″12″ minimum
78207San Antonio4″12″ minimum
78208San Antonio4″12″ minimum
78209San Antonio4″12″ minimum
78210San Antonio4″12″ minimum
78211San Antonio4″12″ minimum
78212San Antonio4″12″ minimum
78213San Antonio4″12″ minimum
78214San Antonio4″12″ minimum
78215San Antonio4″12″ minimum
78216San Antonio4″12″ minimum
78217San Antonio4″12″ minimum
78218San Antonio4″12″ minimum
78219San Antonio4″12″ minimum
78220San Antonio4″12″ minimum
78221San Antonio4″12″ minimum
78222San Antonio4″12″ minimum
78223San Antonio4″12″ minimum
78224San Antonio4″12″ minimum
78225San Antonio4″12″ minimum
78226San Antonio4″12″ minimum
78227San Antonio4″12″ minimum
78228San Antonio4″12″ minimum
78229San Antonio4″12″ minimum
78230San Antonio4″12″ minimum
78231San Antonio4″12″ minimum
78232San Antonio4″12″ minimum
78233San Antonio4″12″ minimum
78234Jbsa Ft Sam Houston4″12″ minimum
78235San Antonio4″12″ minimum
78236Jbsa Lackland4″12″ minimum
78237San Antonio4″12″ minimum
78238San Antonio4″12″ minimum
78239San Antonio4″12″ minimum
78240San Antonio4″12″ minimum
78241San Antonio4″12″ minimum
78242San Antonio4″12″ minimum
78243San Antonio4″12″ minimum
78244San Antonio4″12″ minimum
78245San Antonio4″12″ minimum
78247San Antonio4″12″ minimum
78248San Antonio4″12″ minimum
78249San Antonio4″12–18″
78250San Antonio4″12–18″
78251San Antonio4″12″ minimum
78252San Antonio4″12″ minimum
78253San Antonio5″12–18″
78254San Antonio5″12–18″
78255San Antonio5″12–18″
78256San Antonio5″12–18″
78257San Antonio5″12–18″
78258San Antonio4″12–18″
78259San Antonio4″12″ minimum
78260San Antonio5″12–18″
78261San Antonio5″12–18″
78263San Antonio4″12″ minimum
78264San Antonio4″12″ minimum
78284San Antonio4″12″ minimum
78285San Antonio4″12″ minimum

What this means for your project in Bexar County

Deck footings & piers

Footings must bear below the frost line and at least 12″ below undisturbed ground. For planning in this area, budget for holes around 12″ deep until your permit office confirms the exact figure.

Fence posts

Set posts at least one-third of their above-ground height. Where frost heave is a problem, carry concrete footings below the frost line (about 12″ here in typical soil) and bell or taper the bottom.

Water & irrigation lines

Bury supply lines below the frost depth. Your water utility or plumbing code sets the minimum cover; freezing is rare, but exposed pipes still need insulation.

Slabs & frost-protected foundations

Frost-protected shallow foundations (IRC R403.3) use the 100-year air freezing index — 19 °F-days here — to size perimeter insulation, letting footings sit shallower than the frost line.

Weather stations used

NOAA weather stationDistance100-yr AFI
San Antonio, TX5 mi16
Boerne, TX26 mi32
New Braunfels, TX28 mi29
Poteet, TX30 mi14

Nearby counties

Common questions

What is the frost line depth in Bexar County?

About 4 inches in typical soil, based on NOAA's 100-year air freezing index. Across the county's ZIP codes the estimate runs from 4 to 5 inches.

How deep should footings be in Bexar County, Texas?

Codes in climates like this commonly require 12 inches (code minimum). The Bexar County building department publishes the required frost depth in its adopted code (IRC Table R301.2).

Does frost depth vary within Bexar County?

Very little. Estimates across the county stay within 1 inches. Soil type matters more than location here.