Frost Line Depth in Cape May County, NJ: 30 in (New Jersey rule)

State-set value

30in

76 cm · 2 ft 6 in

30 in (New Jersey rule)

Set by the state: N.J.A.C. 5:23-3.21 Table R301.2, South New Jersey zone (Cape May County).

Source and how we checked

Cape May County does not publish its own value; the state rule applies.

Document: law.cornell.edu

Climate: 72 nights a year at or below 32 °F (NOAA 1991–2020, Cape May 2 Nw, 10.3 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

72nights a year at or below 32 °F
56%of nearby soil rated “moderate” for frost action (USDA)

How deep is the frost line in Cape May County?

New Jersey sets the frost footing depth for Cape May County at 30 in (76 cm). Footings, piers and other permanent supports must reach at least this depth (IRC R403.1.4.1).

Who sets the frost line depth in Cape May County?

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

How deep do footings, decks and water lines need to be in Cape May County?

House or garage footing Deck footing Water service line Fence post

House or garage footing in Cape May County: dig at least 30 in (76 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Cape May County with a 30 in frost line
Project	Depth	Rule
House or garage footing	30 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	30 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	36 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	30 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 Cape May County?

Average lows are at or below freezing from Jan to Feb. 72 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 28.5 °F.

NOAA 1991–2020 climate normals, Cape May 2 Nw station, 10.3 mi away, elevation 20 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	28.5	29.4	35.4	44.1	53.5	63	68.3	67.2	61.7	50.7	40.6	33
High	43.3	45.2	51.7	61.8	71.1	80.1	85.5	84.3	78.6	67.9	56.9	48.1

How likely is the soil in Cape May County to heave?

Moderate 56%High 41%

USDA rates the sampled soil around Cape May County as 2% low, 56% moderate, 41% high for frost action (main soils: Berryland, Mullica, Hammonton).

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 Cape May County?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Cape May County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 30 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Cape May County at a glance

Frost line depth: 30 in (New Jersey rule)
Population (2023 est.): 94,610
Mean annual temperature: 56.2 °F
ZIP codes (16): 08202 · 08204 · 08210 · 08212 · 08223 · 08226 · 08230 · 08242 · 08243 · 08245 · 08246 · 08247 · 08248 · 08251 · 08260 · 08270