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

No official local value

No official frost line depth is published for St. Landry 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: 18 nights a year at or below 32 °F (NOAA 1991–2020, Grand Coteau, 11.9 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

12 inJefferson Parish, the only verified Louisiana code
18nights a year at or below 32 °F
100%of nearby soil rated “none” for frost action (USDA)

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

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

What frost line depth does St. Landry 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. Landry 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. Landry Parish?

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

House or garage footing Deck footing Water service line Fence post

House or garage footing in St. Landry 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. Landry 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. Landry Parish?

St. Landry Parish never averages a low below freezing. 18 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 41.4 °F.

NOAA 1991–2020 climate normals, Grand Coteau station, 11.9 mi away, elevation 55 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	41.4	44.7	50.7	56.8	64.5	70.4	72.6	72.3	67.7	57.8	48.3	43.3
High	63.5	67.2	73.5	79.4	85.5	90.2	91.6	92	88.3	81.2	71.4	65.1

St. Landry Parish has fewer freezing nights than 15 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. Landry Parish to heave?

None 100%

USDA rates the sampled soil around St. Landry Parish as 100% none for frost action (main soils: Baldwin, Sharkey, Iberia).

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

St. Landry Parish at a glance

Frost line depth: No official local value
Population (2023 est.): 81,464
Mean annual temperature: 68.3 °F
ZIP codes (19): 70512 · 70520 · 70525 · 70535 · 70541 · 70550 · 70551 · 70570 · 70577 · 70584 · 70586 · 70589 · 70750 · 71322 · 71345 · 71353 · 71356 · 71358 · 71362