Frost Line Depth in St. Tammany Parish, LA: Set Locally (Jefferson Parish: 12 in)

No official local value

No official frost line depth is published for St. Tammany Parish.

No verified code nearby. The only verified Louisiana code we read, Jefferson Parish’s, uses 12 in.

Source and how we checked

We searched this place’s own code and website and found no published frost line depth.

Climate: 24 nights a year at or below 32 °F (NOAA 1991–2020, Slidell Airport, 9 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

12 inJefferson Parish, the only verified Louisiana code
24nights a year at or below 32 °F
100%of nearby soil rated “none” for frost action (USDA)

Does St. Tammany Parish have an official frost line depth?

No adopted frost line depth found for St. Tammany Parish in its official documents (checked Oct 2026). No verified code lies near St. Tammany Parish; the only Louisiana code we verified, Jefferson Parish’s, uses 12 in. Ask the building department for St. Tammany Parish’s own number before you dig.

What frost line depth does St. Tammany Parish use for footings under Table R301.2(1)?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the St. Tammany Parish building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 12 in (the deepest verified state value) unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

How deep do footings, decks and water lines need to be in St. Tammany Parish?

Drawn with the deepest Louisiana official value (12 in). Confirm St. Tammany Parish’s own depth before you dig.

House or garage footing Deck footing Water service line Fence post

House or garage footing in St. Tammany Parish: dig at least 12 in (30 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Using the nearby official value of 12 in until St. Tammany Parish confirms its own
Project	Depth	Rule
House or garage footing	12 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	12 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	18 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	12 in	No code rule; common practice is below the frost line

Work out posts, concrete and footing sizes with the fence post depth calculator or the deck footing calculator.

How cold does it get in St. Tammany Parish?

St. Tammany Parish never averages a low below freezing. 24 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 40.7 °F.

NOAA 1991–2020 climate normals, Slidell Airport station, 9 mi away, elevation 27 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	40.7	44.4	50	56.1	63.8	70.9	73.1	72.9	68.5	57.4	46.7	42.8
High	62	65.9	71.8	77.9	84.9	89.7	91.1	91.2	88	80.5	71	64.3

St. Tammany Parish has more freezing nights than 20 of the 33 other Louisiana places we track. The Louisiana median is 18. Coldest: Lincoln Parish; mildest: New Orleans.

How likely is the soil in St. Tammany Parish to heave?

None 100%

USDA rates the sampled soil around St. Tammany Parish as 100% none for frost action (main soils: Stough, Myatt, Prentiss).

USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.

St. Tammany Parish at a glance

Frost line depth: No official local value
Population (2023 est.): 275,583
Mean annual temperature: 67.7 °F
ZIP codes (18): 70420 · 70427 · 70431 · 70433 · 70435 · 70437 · 70438 · 70445 · 70447 · 70448 · 70452 · 70457 · 70458 · 70460 · 70461 · 70463 · 70464 · 70471