Frost Line Depth in Martin County, Florida
- Florida state rule
- Checked Oct 2026
- Sources
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
Martin 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, Port Salerno 5W, 8.4 mi).
Checked Oct 2026. Report a correction
How deep is the frost line in Martin 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 Martin County?
Florida writes this depth into its statewide residential code, so Martin 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 Martin County?
House or garage footing in Martin County: dig at least 12 in (30 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| 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 Martin County?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Martin County never averages a low below freezing. 1 night a year reach 32 °F or colder; Jan is coldest, with an average low of 53.6 °F.
NOAA 1991–2020 climate normals, Port Salerno 5w station, 8.4 mi away, elevation 12 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 53.6 | 54.8 | 57.8 | 61.6 | 67.1 | 71.5 | 72.9 | 73.9 | 72.4 | 68.3 | 62 | 56.7 |
| High | 73.7 | 76.2 | 78.5 | 83.1 | 85.9 | 88.9 | 90.3 | 90.8 | 88.5 | 85.3 | 79.2 | 75.8 |
Martin 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 Martin County to heave?
USDA rates the sampled soil around Martin County as 100% none for frost action (main soils: Riviera, Pineda, Cypress Lake).
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 Martin County?
Martin County at a glance
- Frost line depth
- No Frost Line, 12 in Minimum
- Population (2023 est.)
- 163,315
- Mean annual temperature
- 73.7 °F
- ZIP codes (12)
- 33438 · 33455 · 33458 · 33469 · 33478 · 34956 · 34957 · 34974 · 34990 · 34994 · 34996 · 34997