Meridian, ID Frost Line Depth: 24 in

Verified

24in

61 cm · 2 ft

Set in the building code Meridian has adopted.

Source and how we checked

Document: mcclibraryfunctions.azurewebsites.us

Climate: 108 nights a year at or below 32 °F (NOAA 1991–2020, Boise Air Terminal, 8.6 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

2 of 2nearby verified codes use the same depth
108nights a year at or below 32 °F
78%of nearby soil rated “low” for frost action (USDA)

How deep is the frost line in Meridian?

Meridian's building authority sets the frost line depth at 24 in (61 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 Meridian?

Idaho leaves the frost line depth to each city or county, and Meridian fills it in when it adopts the residential code. The value above comes from Meridian’s own document on mcclibraryfunctions.azurewebsites.us. See how Idaho sets frost line depth.

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

House or garage footing Deck footing Water service line Fence post

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

Minimum depths in Meridian with a 24 in frost line
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 Meridian?

Average lows are at or below freezing from Nov to Feb. 108 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 25.4 °F.

NOAA 1991–2020 climate normals, Boise Air Terminal station, 8.6 mi away, elevation 2,814 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	25.5	29	34.9	39.6	47.5	54.1	61.9	60.8	52.6	41.5	31.7	25.4
High	38.8	46	55.5	62.3	72.3	81.4	92.7	90.7	80	64.8	48.8	38.8

Meridian has fewer freezing nights than 12 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 Meridian use?

2 official codes near Meridian are verified; each links to its document.

Official frost line depths near Meridian
Place	Verified frost line	Distance
Nampa	24 in	8 mi away
Canyon County	24 in	15 mi away

How likely is the soil in Meridian to heave?

Low 78%

USDA rates the sampled soil around Meridian as 78% low, 11% moderate, 11% high for frost action (main soils: Purdam, Elijah, Aquic Torriorthents).

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 Meridian?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Meridian building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 24 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Meridian at a glance

Frost line depth: 24 in
County: Ada County
Population (2023 est.): 134,801
Mean annual temperature: 53.2 °F
ZIP codes (3): 83642 · 83646 · 83709