Frost Line Depth in Joliet, IL: Nearby Codes Require 42 in

No official local value

No official frost line depth is published for Joliet.

Nearby official codes require 42 in (5 verified codes).

Source and how we checked

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

Climate: 126 nights a year at or below 32 °F (NOAA 1991–2020, Joliet Brandon Rd Dam, 2.6 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

42 in5 verified codes within 38 mi
126nights a year at or below 32 °F
60%of nearby soil rated “moderate” for frost action (USDA)

Does Joliet have an official frost line depth?

No adopted frost line depth found for Joliet 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 Joliet’s own number.

What frost line depth does Joliet use for footings under Table R301.2(1)? Is it 42 in, like Bolingbrook?

Call 811 (JULIE) at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Joliet 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 Joliet?

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

House or garage footing Deck footing Water service line Fence post

House or garage footing in Joliet: 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 Joliet 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 Joliet?

Average lows are at or below freezing from Dec to Mar. 126 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 16.6 °F.

NOAA 1991–2020 climate normals, Joliet Brandon Rd Dam station, 2.6 mi away, elevation 543 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	16.6	19.8	29.2	38.9	49.4	59.9	64.1	62.9	55.3	43.4	32.3	22.4
High	31.1	35.4	47	59.9	71	80.3	83.6	81.8	76.2	63.3	48.5	36.4

Joliet has fewer freezing nights than 36 of the 71 other Illinois places we track. The Illinois median is 127. Coldest: Hoffman Estates; mildest: Madison County.

What frost line depth do towns near Joliet use?

5 official codes near Joliet are verified; each links to its document.

Official frost line depths near Joliet
Place	Verified frost line	Distance
Bolingbrook	42 in	12 mi away
Naperville	42 in	16 mi away
Wheaton	42 in	24 mi away
Lombard	42 in	26 mi away
Hoffman Estates	42 in	38 mi away

How likely is the soil in Joliet to heave?

Moderate 60%High 40%

USDA rates the sampled soil around Joliet as 60% moderate, 40% high for frost action (main soils: Elliott, Bryce, Millsdale).

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

Joliet at a glance

Frost line depth: No official local value
County: Will County
Population (2023 est.): 150,489
Mean annual temperature: 50.4 °F
ZIP codes (16): 60403 · 60404 · 60410 · 60421 · 60431 · 60432 · 60433 · 60435 · 60436 · 60441 · 60442 · 60447 · 60451 · 60544 · 60560 · 60586