Frost Line Depth in Simi Valley, CA: Nearby Codes Require 12 in

No official local value

No official frost line depth is published for Simi Valley.

Nearby official codes require 12 in (4 verified codes).

Source and how we checked

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

Climate: 11 nights a year at or below 32 °F (NOAA 1991–2020, Woodland Hills Pierce College, 11.5 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

12 in4 verified codes within 52 mi
11nights a year at or below 32 °F
100%of nearby soil rated “none” for frost action (USDA)

Does Simi Valley have an official frost line depth?

No adopted frost line depth found for Simi Valley in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 12 in. Use the deepest of them until the building department confirms Simi Valley’s own number.

What frost line depth does Simi Valley use for footings under Table R301.2(1)? Is it 12 in, like Paramount?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Simi Valley building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 12 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 Simi Valley?

Drawn with the deepest nearby official value (12 in). Confirm Simi Valley’s own depth before you dig.

House or garage footing Deck footing Water service line Fence post

House or garage footing in Simi Valley: dig at least 12 in (30 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Using the nearby official value of 12 in until Simi Valley confirms its own
Project	Depth	Rule
House or garage footing	12 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	12 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	18 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	12 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 Simi Valley?

Simi Valley never averages a low below freezing. 11 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 42 °F.

NOAA 1991–2020 climate normals, Woodland Hills Pierce College station, 11.5 mi away, elevation 790 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	43.1	43.6	45.9	48.1	52.6	56.9	60.8	60.8	58.5	52.9	46	42
High	69.8	70	74	78	82	88.5	95.1	97.4	93.9	85.2	76.4	68.9

Simi Valley has more freezing nights than 141 of the 208 other California places we track. The California median is 3. Coldest: El Dorado County; mildest: San Diego.

What frost line depth do towns near Simi Valley use?

4 official codes near Simi Valley are verified; each links to its document.

Official frost line depths near Simi Valley
Place	Verified frost line	Distance
Paramount	12 in	42 mi away
Norwalk	12 in	45 mi away
Whittier	12 in	47 mi away
Glendora	12 in	52 mi away

How likely is the soil in Simi Valley to heave?

None 100%

USDA rates the sampled soil around Simi Valley as 100% none for frost action (main soils: Mocho, Soper, Los Osos).

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

Simi Valley at a glance

Frost line depth: No official local value
County: Ventura County
Population (2023 est.): 125,113
Mean annual temperature: 66.3 °F
ZIP codes (4): 91311 · 93021 · 93063 · 93065