Frostline.info

Frost line depth in Davidson County, Tennessee

Frost reaches about 19 inches in typical soil across Davidson County, from 17″ in the mildest ZIP code to 23″ in the coldest. Codes in this climate commonly set footing depth at 18 to 24 inches.

Moderate frost
Estimated frost depth
19″
typical silt/loam soil
Typical code footing depth
18–24″
rule of thumb for this climate
Design freezing index
366
°F-days, 100-year winter
ZIP codes covered
29
#43 of 95 counties in TN (1 = deepest)
19″ 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)24″
Silt / loam (typical yard soil)19″
Clay (holds water)16″

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 Davidson County building or permitting office in Tennessee and call 811 before digging.

Frost depth by ZIP code in Davidson County

ZIPCityEst. frostCode range
37013Antioch18″18–24″
37072Goodlettsville22″18–30″
37076Hermitage18″18–24″
37080Joelton23″18–30″
37115Madison20″18–24″
37138Old Hickory19″18–24″
37189Whites Creek21″18–30″
37201Nashville18″18–24″
37203Nashville18″18–24″
37204Nashville18″18–24″
37205Nashville18″18–24″
37206Nashville18″18–24″
37207Nashville19″18–24″
37208Nashville19″18–24″
37209Nashville19″18–24″
37210Nashville18″18–24″
37211Nashville18″18–24″
37212Nashville18″18–24″
37213Nashville18″18–24″
37214Nashville18″18–24″
37215Nashville18″18–24″
37216Nashville19″18–24″
37217Nashville18″18–24″
37218Nashville19″18–24″
37219Nashville18″18–24″
37220Nashville18″18–24″
37221Nashville17″18–24″
37228Nashville19″18–24″
37238Nashville19″18–24″

What this means for your project in Davidson 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 24″ 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 19″ 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; add a margin below the estimate above for unusually cold winters.

Slabs & frost-protected foundations

Frost-protected shallow foundations (IRC R403.3) use the 100-year air freezing index — 366 °F-days here — to size perimeter insulation, letting footings sit shallower than the frost line.

Weather stations used

NOAA weather stationDistance100-yr AFI
Nashville, TN6 mi332
Franklin Sewage Plant, TN17 mi298
Springfield Exp Sta, TN21 mi628
Murfreesboro 5 N, TN28 mi366

Nearby counties

Common questions

What is the frost line depth in Davidson County?

About 19 inches in typical soil, based on NOAA's 100-year air freezing index. Across the county's ZIP codes the estimate runs from 17 to 23 inches.

How deep should footings be in Davidson County, Tennessee?

Codes in climates like this commonly require 18 to 24 inches. The Davidson County building department publishes the required frost depth in its adopted code (IRC Table R301.2).

Does frost depth vary within Davidson County?

Yes. Estimates differ by 6 inches between the coldest and mildest ZIP codes, mostly from latitude and elevation. Check your own ZIP below.