Placer County, CA Frost Line Depth: 18

Verified

18in

46 cm · 1 ft 6 in

18–24 in Above 5,000 ft

Set in the building code Placer County has adopted.

Source and how we checked

Document: placer.ca.gov

Climate: 49 nights a year at or below 32 °F (NOAA 1991–2020, Georgetown Rs, 9.8 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

49nights a year at or below 32 °F
65%of nearby soil rated “low” for frost action (USDA)

How deep is the frost line in Placer County?

Placer County's building authority sets the frost line depth at 18 in (46 cm) at 5,001–7,000 ft and 24 in (61 cm) at 7,001–8,000 ft elevation. Footings, piers and other permanent supports must reach at least this depth (IRC R403.1.4.1).

Who sets the frost line depth in Placer County?

California leaves the frost line depth to each city or county, and Placer County fills it in when it adopts the residential code. The value above comes from Placer County’s own document on placer.ca.gov. See how California sets frost line depth.

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

House or garage footing Deck footing Water service line Fence post

House or garage footing in Placer County: dig at least 18 in (46 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Placer County with a 18 in frost line
Project	Depth	Rule
House or garage footing	18 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	18 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	24 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	18 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 Placer County?

Placer County never averages a low below freezing. 49 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 35.8 °F.

NOAA 1991–2020 climate normals, Georgetown Rs station, 9.8 mi away, elevation 3,001 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	36.4	36	37.9	41	47.7	56	62.9	62.5	57.3	49.3	41.1	35.8
High	52.3	54.8	58.6	64	71.7	81.7	90.7	90.6	85.7	74	58.8	50.4

Placer County has more freezing nights than 199 of the 208 other California places we track. The California median is 3. Coldest: El Dorado County; mildest: San Diego.

How likely is the soil in Placer County to heave?

None 27%Low 65%

USDA rates the sampled soil around Placer County as 27% none, 65% low, 8% high for frost action (main soils: Hurlbut, Jocal, Sites).

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 Placer County?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Placer County building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 18 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Placer County at a glance

Frost line depth: 18–24 in Above 5,000 ft
Population (2023 est.): 423,561
Mean annual temperature: 58.2 °F
ZIP codes (34): 95602 · 95603 · 95604 · 95626 · 95631 · 95648 · 95650 · 95658 · 95661 · 95663 · 95668 · 95677 · 95678 · 95681 · 95701 · 95703 · 95713 · 95714 · 95715 · 95717 · 95722 · 95728 · 95736 · 95746 · 95747 · 95765 · 96140 · 96141 · 96142 · 96143 · 96145 · 96146 · 96148 · 96161