Frostline.info

Frost line depth in Alameda County, California

Frost reaches about 1 inches in typical soil across Alameda County, from 0″ in the mildest ZIP code to 3″ in the coldest. Codes in this climate commonly set footing depth at 12 inches (code minimum).

Shallow frost
Estimated frost depth
1″
typical silt/loam soil
Typical code footing depth
12″ minimum
rule of thumb for this climate
Design freezing index
2
°F-days, 100-year winter
ZIP codes covered
49
#41 of 58 counties in CA (1 = deepest)
1″ 0″12″24″36″ ground frozen
Est. frost (typical soil) Typical code footing depth Clay–sand range

Frost depth by soil type

Soil typeEst. frost depth
Sand / gravel (drains well)2″
Silt / loam (typical yard soil)1″
Clay (holds water)1″

County average. Methodology.

Verify before you dig. These are climate-based estimates. The legally required frost depth is the figure your building department publishes in its IRC Table R301.2 (climatic and geographic design criteria). Call the Alameda County building or permitting office in California and call 811 before digging.

Frost depth by ZIP code in Alameda County

ZIPCityEst. frostCode range
94501Alameda1″12″ minimum
94502Alameda2″12″ minimum
94536Fremont0″12″ minimum
94538Fremont0″12″ minimum
94539Fremont1″12″ minimum
94541Hayward2″12″ minimum
94542Hayward2″12″ minimum
94544Hayward2″12″ minimum
94545Hayward2″12″ minimum
94546Castro Valley3″12″ minimum
94550Livermore1″12″ minimum
94551Livermore2″12″ minimum
94552Castro Valley3″12″ minimum
94555Fremont0″12″ minimum
94560Newark0″12″ minimum
94566Pleasanton2″12″ minimum
94568Dublin2″12″ minimum
94577San Leandro2″12″ minimum
94578San Leandro2″12″ minimum
94579San Leandro2″12″ minimum
94580San Lorenzo2″12″ minimum
94586Sunol1″12″ minimum
94587Union City0″12″ minimum
94588Pleasanton2″12″ minimum
94601Oakland2″12″ minimum
94602Oakland2″12″ minimum
94603Oakland2″12″ minimum
94605Oakland3″12″ minimum
94606Oakland1″12″ minimum
94607Oakland0″12″ minimum
94608Emeryville0″12″ minimum
94609Oakland1″12″ minimum
94610Oakland1″12″ minimum
94611Oakland1″12″ minimum
94612Oakland1″12″ minimum
94615Oakland0″12″ minimum
94617Oakland1″12″ minimum
94618Oakland1″12″ minimum
94619Oakland2″12″ minimum
94621Oakland2″12″ minimum
94702Berkeley0″12″ minimum
94703Berkeley0″12″ minimum
94704Berkeley0″12″ minimum
94705Berkeley0″12″ minimum
94706Albany0″12″ minimum
94707Berkeley0″12″ minimum
94708Berkeley0″12″ minimum
94709Berkeley0″12″ minimum
94710Berkeley0″12″ minimum

What this means for your project in Alameda County

Deck footings & piers

Footings must bear below the frost line and at least 12″ below undisturbed ground. For planning in this area, budget for holes around 12″ deep until your permit office confirms the exact figure.

Fence posts

Set posts at least one-third of their above-ground height. Where frost heave is a problem, carry concrete footings below the frost line (about 12″ here in typical soil) and bell or taper the bottom.

Water & irrigation lines

Bury supply lines below the frost depth. Your water utility or plumbing code sets the minimum cover; freezing is rare, but exposed pipes still need insulation.

Slabs & frost-protected foundations

Frost-protected shallow foundations (IRC R403.3) use the 100-year air freezing index — 2 °F-days here — to size perimeter insulation, letting footings sit shallower than the frost line.

Weather stations used

NOAA weather stationDistance100-yr AFI
Saint Marys College, CA7 mi11
Berkeley, CA10 mi0
S F Federal Bldg., CA15 mi0
San Francisco, CA16 mi0

Nearby counties

Common questions

What is the frost line depth in Alameda County?

About 1 inches in typical soil, based on NOAA's 100-year air freezing index. Across the county's ZIP codes the estimate runs from 0 to 3 inches.

How deep should footings be in Alameda County, California?

Codes in climates like this commonly require 12 inches (code minimum). The Alameda County building department publishes the required frost depth in its adopted code (IRC Table R301.2).

Does frost depth vary within Alameda County?

Very little. Estimates across the county stay within 3 inches. Soil type matters more than location here.