Frost Line Depth in Story County, IA: Nearby Codes Require 42 in

No official local value

No official frost line depth is published for Story County.

Nearby official codes require 42 in (3 verified codes).

Source and how we checked

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

Climate: 151 nights a year at or below 32 °F (NOAA 1991–2020, Colo, 7.7 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

42 in3 verified codes within 38 mi
151nights a year at or below 32 °F
67%of nearby soil rated “moderate” for frost action (USDA)

Does Story County have an official frost line depth?

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

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

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

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

House or garage footing Deck footing Water service line Fence post

House or garage footing in Story 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 Story 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 Story County?

Average lows are at or below freezing from Nov to Mar. 151 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 9.8 °F.

NOAA 1991–2020 climate normals, Colo station, 7.7 mi away, elevation 1,000 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	9.8	13.9	25.7	37	49.2	60.2	63.3	61.3	51.9	39.3	27.2	16.1
High	26.9	31.4	45	59.2	70.4	79.8	83	81	75	62	45.7	32.2

Story County has more freezing nights than 22 of the 28 other Iowa places we track. The Iowa median is 144. Coldest: Cerro Gordo County; mildest: Davenport.

What frost line depth do towns near Story County use?

3 official codes near Story County are verified; each links to its document.

Official frost line depths near Story County
Place	Verified frost line	Distance
Ankeny	42 in	22 mi away
West Des Moines	42 in	37 mi away
Dallas County	42 in	38 mi away

How likely is the soil in Story County to heave?

Moderate 67%High 33%

USDA rates the sampled soil around Story County as 67% moderate, 33% high for frost action (main soils: Clarion, Nicollet, Webster).

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

Story County at a glance

Frost line depth: No official local value
Population (2023 est.): 98,566
Mean annual temperature: 47.8 °F
ZIP codes (23): 50010 · 50012 · 50013 · 50014 · 50046 · 50055 · 50056 · 50105 · 50124 · 50134 · 50154 · 50161 · 50201 · 50206 · 50226 · 50230 · 50236 · 50239 · 50243 · 50244 · 50247 · 50248 · 50278