Frost Line Depth in Allen County, IN: 36 in (Indiana rule)

State-set value

36in

91 cm · 3 ft

36 in (Indiana rule)

Set by the state: Indiana Residential Code Table R301.2(1), Allen County (state sets the whole design table).

Source and how we checked

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

Document: codes.iccsafe.org

Climate: 124 nights a year at or below 32 °F (NOAA 1991–2020, Ft Wayne International Airport, 10.9 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

124nights a year at or below 32 °F
94%of nearby soil rated “high” for frost action (USDA)

How deep is the frost line in Allen County?

Indiana sets the frost footing depth for Allen County at 36 in (91 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 Allen County?

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

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

House or garage footing Deck footing Water service line Fence post

House or garage footing in Allen County: dig at least 36 in (91 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Allen County with a 36 in frost line
Project	Depth	Rule
House or garage footing	36 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	36 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	42 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	36 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 Allen County?

Average lows are at or below freezing from Dec to Mar. 124 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 18.4 °F.

NOAA 1991–2020 climate normals, Ft Wayne International Airport station, 10.9 mi away, elevation 791 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	18.4	21	29.4	39.4	50.4	60.3	63.5	61.2	53.4	42.8	32.8	24.2
High	32.6	36.5	47.8	60.9	72.2	81	84.1	82	76.1	63.7	49.4	37.5

Allen County has more freezing nights than 35 of the 55 other Indiana places we track. The Indiana median is 120. Coldest: LaGrange County; mildest: Evansville.

How likely is the soil in Allen County to heave?

High 94%

USDA rates the sampled soil around Allen County as 6% moderate, 94% high for frost action (main soils: Blount, Lenawee, Rensselaer).

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 Allen County?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Allen County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 36 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Allen County at a glance

Frost line depth: 36 in (Indiana rule)
Population (2023 est.): 394,545
Mean annual temperature: 50.9 °F
ZIP codes (33): 46704 · 46706 · 46723 · 46733 · 46741 · 46743 · 46745 · 46748 · 46765 · 46773 · 46774 · 46777 · 46783 · 46788 · 46797 · 46798 · 46799 · 46802 · 46803 · 46804 · 46805 · 46806 · 46807 · 46808 · 46809 · 46814 · 46815 · 46816 · 46818 · 46819 · 46825 · 46835 · 46845