Frost Line Depth in St. Lucie County, FL: No Frost Line, 12 in Minimum

State-set value

No Frost Line, 12 in Minimum

Florida Building Code–Residential: no frost line (Table R301.2 'Reserved'); 12-in footing minimum, R403.1.4.

Source and how we checked

St. Lucie County does not publish its own value; the state rule applies.

Document: up.codes

Climate: 1 night a year at or below 32 °F (NOAA 1991–2020, Ft Pierce, 7.1 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

1nights a year at or below 32 °F
100%of nearby soil rated “none” for frost action (USDA)

How deep is the frost line in St. Lucie County?

Florida's building code sets no frost line; footings must still be at least 12 in (30 cm) below undisturbed ground.

Who sets the frost line depth in St. Lucie County?

Florida writes this depth into its statewide residential code, so St. Lucie County’s building department enforces the state’s number rather than setting its own. See how Florida sets frost line depth.

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

House or garage footing Deck footing Water service line Fence post

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

Minimum depths in St. Lucie County with a 12 in frost line
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. Lucie County?

St. Lucie County never averages a low below freezing. 1 night a year reach 32 °F or colder; Jan is coldest, with an average low of 53 °F.

NOAA 1991–2020 climate normals, Ft Pierce station, 7.1 mi away, elevation 25 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	53	55.4	58.5	63.9	69	72.9	74.1	74.6	74	69.6	62.2	56.5
High	72.4	74.3	77	80.8	84.4	87.6	89.2	89.2	87.5	83.8	78.3	74.4

St. Lucie County has fewer freezing nights than 53 of the 110 other Florida places we track. The Florida median is 1. Coldest: Okaloosa County; mildest: Port St. Lucie.

How likely is the soil in St. Lucie County to heave?

None 100%

USDA rates the sampled soil around St. Lucie County as 100% none for frost action (main soils: Pineda, Riviera, Wabasso).

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

How do you confirm the frost line before you dig in St. Lucie County?

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

St. Lucie County at a glance

Frost line depth: No Frost Line, 12 in Minimum
Population (2023 est.): 373,586
Mean annual temperature: 73.5 °F
ZIP codes (17): 34945 · 34946 · 34947 · 34949 · 34950 · 34951 · 34952 · 34953 · 34957 · 34972 · 34981 · 34982 · 34983 · 34984 · 34986 · 34987 · 34990