Frostline.info

Frost line depth in Monmouth County, New Jersey

Frost reaches about 24 inches in typical soil across Monmouth County. Codes in this climate commonly set footing depth at 18 to 30 inches.

Moderate frost
Estimated frost depth
24″
typical silt/loam soil
Typical code footing depth
18–30″
rule of thumb for this climate
Design freezing index
578
°F-days, 100-year winter
ZIP codes covered
49
#12 of 21 counties in NJ (1 = deepest)
24″ 0″12″24″36″48″ 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)30″
Silt / loam (typical yard soil)24″
Clay (holds water)20″

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 Monmouth County building or permitting office in New Jersey and call 811 before digging.

Frost depth by ZIP code in Monmouth County

ZIPCityEst. frostCode range
07701Red Bank23″18–30″
07702Shrewsbury23″18–30″
07703Fort Monmouth23″18–30″
07704Fair Haven23″18–30″
07711Allenhurst23″18–30″
07712Asbury Park23″18–30″
07716Atlantic Highlands23″18–30″
07717Avon By The Sea24″18–30″
07718Belford23″18–30″
07719Belmar24″24–30″
07720Bradley Beach24″18–30″
07721Cliffwood24″18–30″
07722Colts Neck25″24–30″
07723Deal23″18–30″
07724Eatontown23″18–30″
07726Englishtown25″24–30″
07727Farmingdale25″24–30″
07728Freehold25″24–30″
07730Hazlet24″18–30″
07731Howell25″24–30″
07732Highlands23″18–30″
07733Holmdel24″18–30″
07734Keansburg23″18–30″
07735Keyport23″18–30″
07737Leonardo23″18–30″
07738Lincroft23″18–30″
07739Little Silver23″18–30″
07740Long Branch23″18–30″
07746Marlboro25″24–30″
07747Matawan24″18–30″
07748Middletown23″18–30″
07750Monmouth Beach23″18–30″
07751Morganville25″24–30″
07753Neptune24″18–30″
07755Oakhurst23″18–30″
07756Ocean Grove23″18–30″
07757Oceanport23″18–30″
07758Port Monmouth23″18–30″
07760Rumson23″18–30″
07762Spring Lake24″18–30″
07764West Long Branch23″18–30″
07799Eatontown25″24–30″
08501Allentown23″18–30″
08510Millstone Township25″24–30″
08514Cream Ridge25″24–30″
08535Millstone Township25″24–30″
08730Brielle24″24–30″
08736Manasquan24″24–30″
08750Sea Girt24″24–30″

What this means for your project in Monmouth 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 30″ 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 24″ 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; add a margin below the estimate above for unusually cold winters.

Slabs & frost-protected foundations

Frost-protected shallow foundations (IRC R403.3) use the 100-year air freezing index — 578 °F-days here — to size perimeter insulation, letting footings sit shallower than the frost line.

Weather stations used

NOAA weather stationDistance100-yr AFI
Long Branch 2 S, NJ6 mi539
Freehold, NJ7 mi646
Hightstown 1 N, NJ20 mi641
Ny Westerleigh Stat Is, NY21 mi521

Nearby counties

Common questions

What is the frost line depth in Monmouth County?

About 24 inches in typical soil, based on NOAA's 100-year air freezing index. Across the county's ZIP codes the estimate runs from 23 to 25 inches.

How deep should footings be in Monmouth County, New Jersey?

Codes in climates like this commonly require 18 to 30 inches. The Monmouth County building department publishes the required frost depth in its adopted code (IRC Table R301.2).

Does frost depth vary within Monmouth County?

Very little. Estimates across the county stay within 2 inches. Soil type matters more than location here.