Frost Line Depth in Bonner County, ID: Post Falls Requires 24 in

No official local value

No official frost line depth is published for Bonner County.

Nearby official codes require 24 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: 156 nights a year at or below 32 °F (NOAA 1991–2020, Sandpoint Exp Stn, 3.6 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

24 in1 verified code within 44 mi
156nights a year at or below 32 °F
48%of nearby soil rated “high” for frost action (USDA)

Does Bonner County have an official frost line depth?

No adopted frost line depth found for Bonner County in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 24 in. Use the deepest of them until the building department confirms Bonner County’s own number.

What frost line depth does Bonner County use for footings under Table R301.2(1)? Is it 24 in, like Post Falls?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Bonner County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 24 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 Bonner County?

Drawn with the deepest nearby official value (24 in). Confirm Bonner County’s own depth before you dig.

House or garage footing Deck footing Water service line Fence post

House or garage footing in Bonner County: dig at least 24 in (61 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Using the nearby official value of 24 in until Bonner County confirms its own
Project	Depth	Rule
House or garage footing	24 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	24 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	30 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	24 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 Bonner County?

Average lows are at or below freezing from Nov to Mar. 156 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 22.8 °F.

NOAA 1991–2020 climate normals, Sandpoint Exp Stn station, 3.6 mi away, elevation 2,126 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	22.9	23.7	28.6	34.5	41.8	47.5	51.6	49.8	42.4	34.1	28.9	22.8
High	33.6	38.4	46.4	55.6	65.8	71.8	81.8	81.9	71.7	56.3	41.8	33.5

Bonner County has more freezing nights than 9 of the 13 other Idaho places we track. The Idaho median is 132. Coldest: Madison County; mildest: Canyon County.

What frost line depth do towns near Bonner County use?

One official code near Bonner County is verified.

Official frost line depths near Bonner County
Place	Verified frost line	Distance
Post Falls	24 in	44 mi away

How likely is the soil in Bonner County to heave?

Low 35%Moderate 18%High 48%

USDA rates the sampled soil around Bonner County as 35% low, 18% moderate, 48% high for frost action (main soils: Priestlake, Pend Oreille, Vay).

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

Bonner County at a glance

Frost line depth: No official local value
Population (2023 est.): 52,547
Mean annual temperature: 46.1 °F
ZIP codes (18): 83801 · 83803 · 83804 · 83809 · 83811 · 83813 · 83821 · 83822 · 83825 · 83836 · 83840 · 83841 · 83848 · 83852 · 83856 · 83860 · 83864 · 83869