Frost Line Depth in Rockland County, NY: Mount Vernon Requires 42 in

No official local value

No official frost line depth is published for Rockland County.

Nearby official codes require 42 in (1 verified code).

Source and how we checked

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

Climate: 116 nights a year at or below 32 °F (NOAA 1991–2020, Yorktown Hts 1W, 14.1 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

42 in1 verified code within 20 mi
116nights a year at or below 32 °F
54%of nearby soil rated “moderate” for frost action (USDA)

Does Rockland County have an official frost line depth?

No adopted frost line depth found for Rockland County in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 42 in. Use the deepest of them until the building department confirms Rockland County’s own number.

What frost line depth does Rockland County use for footings under Table R301.2(1)? Is it 42 in, like Mount Vernon?

Call 811 (Dig Safely New York) at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Rockland County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 42 in (the deepest nearby 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 Rockland County?

Drawn with the deepest nearby official value (42 in). Confirm Rockland County’s own depth before you dig.

House or garage footing Deck footing Water service line Fence post

House or garage footing in Rockland County: dig at least 42 in (107 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Using the nearby official value of 42 in until Rockland County confirms its own
Project	Depth	Rule
House or garage footing	42 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	42 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	48 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	42 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 Rockland County?

Average lows are at or below freezing from Nov to Mar. 116 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 16.7 °F.

NOAA 1991–2020 climate normals, Yorktown Hts 1w station, 14.1 mi away, elevation 670 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	16.7	17.9	25.4	35.9	45.9	55.2	60.8	59.3	51.9	40.9	31.5	23.3
High	35.5	38.6	46.8	59.7	69.6	78	83	81.1	74.4	62.5	51.4	40.8

Rockland County has fewer freezing nights than 52 of the 67 other New York places we track. The New York median is 141. Coldest: Franklin County; mildest: Kings County.

What frost line depth do towns near Rockland County use?

One official code near Rockland County is verified.

Official frost line depths near Rockland County
Place	Verified frost line	Distance
Mount Vernon	42 in	20 mi away

How likely is the soil in Rockland County to heave?

Low 33%Moderate 54%High 13%

USDA rates the sampled soil around Rockland County as 33% low, 54% moderate, 13% high for frost action (main soils: Wethersfield, Cheshire, Yalesville).

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

Rockland County at a glance

Frost line depth: No official local value
Population (2023 est.): 340,807
Mean annual temperature: 49.4 °F
ZIP codes (26): 10901 · 10911 · 10913 · 10920 · 10923 · 10927 · 10931 · 10952 · 10954 · 10956 · 10960 · 10962 · 10964 · 10965 · 10968 · 10970 · 10974 · 10976 · 10977 · 10980 · 10983 · 10984 · 10986 · 10989 · 10993 · 10994