Frostline.info

Frost line depth in Maricopa County, Arizona

Frost reaches about 0 inches in typical soil across Maricopa County, from 0″ in the mildest ZIP code to 4″ in the coldest. Codes in this climate commonly set footing depth at 12 inches (code minimum).

No meaningful frost
Estimated frost depth
0″
typical silt/loam soil
Typical code footing depth
12″ minimum
rule of thumb for this climate
Design freezing index
0
°F-days, 100-year winter
ZIP codes covered
133
#14 of 15 counties in AZ (1 = deepest)
0″12″24″36″ ground
Est. frost (typical soil) Typical code footing depth Clay–sand range

Frost depth by soil type

Soil typeEst. frost depth
Sand / gravel (drains well)0″
Silt / loam (typical yard soil)0″
Clay (holds water)0″

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 Maricopa County building or permitting office in Arizona and call 811 before digging.

Frost depth by ZIP code in Maricopa County

ZIPCityEst. frostCode range
85003Phoenix0″12″ minimum
85004Phoenix0″12″ minimum
85006Phoenix0″12″ minimum
85007Phoenix0″12″ minimum
85008Phoenix0″12″ minimum
85009Phoenix0″12″ minimum
85012Phoenix0″12″ minimum
85013Phoenix0″12″ minimum
85014Phoenix0″12″ minimum
85015Phoenix0″12″ minimum
85016Phoenix0″12″ minimum
85017Phoenix0″12″ minimum
85018Phoenix0″12″ minimum
85019Phoenix0″12″ minimum
85020Phoenix0″12″ minimum
85021Phoenix0″12″ minimum
85022Phoenix0″12″ minimum
85023Phoenix0″12″ minimum
85024Phoenix0″12″ minimum
85026Phoenix0″12″ minimum
85027Phoenix0″12″ minimum
85028Phoenix0″12″ minimum
85029Phoenix0″12″ minimum
85031Phoenix0″12″ minimum
85032Phoenix0″12″ minimum
85033Phoenix0″12″ minimum
85034Phoenix0″12″ minimum
85035Phoenix0″12″ minimum
85037Phoenix0″12″ minimum
85039Phoenix0″12″ minimum
85040Phoenix0″12″ minimum
85041Phoenix0″12″ minimum
85042Phoenix0″12″ minimum
85043Phoenix0″12″ minimum
85044Phoenix0″12″ minimum
85045Phoenix0″12″ minimum
85048Phoenix0″12″ minimum
85050Phoenix0″12″ minimum
85051Phoenix0″12″ minimum
85053Phoenix0″12″ minimum
85054Phoenix0″12″ minimum
85065Phoenix0″12″ minimum
85073Phoenix0″12″ minimum
85083Phoenix0″12″ minimum
85085Phoenix0″12″ minimum
85086Phoenix0″12″ minimum
85087New River4″12″ minimum
85142Queen Creek1″12″ minimum
85201Mesa0″12″ minimum
85202Mesa0″12″ minimum
85203Mesa0″12″ minimum
85204Mesa0″12″ minimum
85205Mesa0″12″ minimum
85206Mesa0″12″ minimum
85207Mesa0″12″ minimum
85208Mesa0″12″ minimum
85209Mesa0″12″ minimum
85210Mesa0″12″ minimum
85212Mesa0″12″ minimum
85213Mesa0″12″ minimum
85215Mesa0″12″ minimum
85224Chandler0″12″ minimum
85225Chandler0″12″ minimum
85226Chandler0″12″ minimum
85233Gilbert0″12″ minimum
85234Gilbert0″12″ minimum
85248Chandler0″12″ minimum
85249Chandler1″12″ minimum
85250Scottsdale0″12″ minimum
85251Scottsdale0″12″ minimum
85253Paradise Valley0″12″ minimum
85254Scottsdale0″12″ minimum
85255Scottsdale0″12″ minimum
85256Scottsdale0″12″ minimum
85257Scottsdale0″12″ minimum
85258Scottsdale0″12″ minimum
85259Scottsdale0″12″ minimum
85260Scottsdale0″12″ minimum
85262Scottsdale0″12″ minimum
85263Rio Verde0″12″ minimum
85264Fort Mcdowell0″12″ minimum
85266Scottsdale0″12″ minimum
85268Fountain Hills0″12″ minimum
85281Tempe0″12″ minimum
85282Tempe0″12″ minimum
85283Tempe0″12″ minimum
85284Tempe0″12″ minimum
85286Chandler0″12″ minimum
85288Tempe0″12″ minimum
85295Gilbert0″12″ minimum
85296Gilbert0″12″ minimum
85297Gilbert1″12″ minimum
85298Gilbert1″12″ minimum
85301Glendale0″12″ minimum
85302Glendale0″12″ minimum
85303Glendale0″12″ minimum
85304Glendale0″12″ minimum
85305Glendale0″12″ minimum
85306Glendale0″12″ minimum
85307Glendale0″12″ minimum
85308Glendale0″12″ minimum
85310Glendale0″12″ minimum
85322Arlington0″12″ minimum
85323Avondale0″12″ minimum
85326Buckeye0″12″ minimum
85331Cave Creek0″12″ minimum
85335El Mirage0″12″ minimum
85337Gila Bend0″12″ minimum
85338Goodyear0″12″ minimum
85339Laveen0″12″ minimum
85340Litchfield Park0″12″ minimum
85342Morristown2″12″ minimum
85345Peoria0″12″ minimum
85351Sun City0″12″ minimum
85353Tolleson0″12″ minimum
85354Tonopah0″12″ minimum
85355Waddell0″12″ minimum
85361Wittmann1″12″ minimum
85363Youngtown0″12″ minimum
85373Sun City0″12″ minimum
85374Surprise0″12″ minimum
85375Sun City West0″12″ minimum
85378Surprise0″12″ minimum
85379Surprise0″12″ minimum
85381Peoria0″12″ minimum
85382Peoria0″12″ minimum
85383Peoria0″12″ minimum
85387Surprise1″12″ minimum
85388Surprise0″12″ minimum
85390Wickenburg2″12″ minimum
85392Avondale0″12″ minimum
85395Goodyear0″12″ minimum
85396Buckeye0″12″ minimum

What this means for your project in Maricopa 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 — 0 °F-days here — to size perimeter insulation, letting footings sit shallower than the frost line.

Weather stations used

NOAA weather stationDistance100-yr AFI
Deer Valley, AZ5 mi0
Phoenix, AZ6 mi0
South Phoenix, AZ9 mi0
Tempe, AZ10 mi0

Nearby counties

Common questions

What is the frost line depth in Maricopa County?

About 0 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 4 inches.

How deep should footings be in Maricopa County, Arizona?

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

Does frost depth vary within Maricopa County?

Very little. Estimates across the county stay within 4 inches. Soil type matters more than location here.