Frostline.info

Frost line depth in Hartford County, Connecticut

Frost reaches about 31 inches in typical soil across Hartford County, from 29″ in the mildest ZIP code to 38″ in the coldest. Codes in this climate commonly set footing depth at 24 to 42 inches.

Deep frost
Estimated frost depth
31″
typical silt/loam soil
Typical code footing depth
24–42″
rule of thumb for this climate
Design freezing index
990
°F-days, 100-year winter
ZIP codes covered
56
#3 of 8 counties in CT (1 = deepest)
31″ 0″12″24″36″48″60″ 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)39″
Silt / loam (typical yard soil)31″
Clay (holds water)27″

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 Hartford County building or permitting office in Connecticut and call 811 before digging.

Frost depth by ZIP code in Hartford County

ZIPCityEst. frostCode range
06001Avon30″24–42″
06002Bloomfield30″24–36″
06010Bristol31″24–42″
06013Burlington31″24–42″
06016Broad Brook30″24–42″
06019Canton33″30–42″
06023East Berlin29″24–36″
06026East Granby32″30–42″
06027East Hartland37″30–48″
06032Farmington30″24–42″
06033Glastonbury30″24–36″
06035Granby33″30–42″
06037Berlin29″24–36″
06040Manchester30″24–36″
06042Manchester30″24–36″
06051New Britain30″24–36″
06052New Britain30″24–36″
06053New Britain30″24–36″
06060North Granby35″30–48″
06062Plainville30″24–36″
06065Riverton37″30–48″
06067Rocky Hill30″24–36″
06070Simsbury32″30–42″
06073South Glastonbury30″24–36″
06074South Windsor30″24–42″
06078Suffield31″24–42″
06081Tariffville32″30–42″
06082Enfield30″24–42″
06085Unionville30″24–42″
06088East Windsor30″24–42″
06089Weatogue30″24–42″
06090West Granby34″30–42″
06091West Hartland38″30–48″
06092West Simsbury33″30–42″
06093West Suffield32″30–42″
06095Windsor30″24–36″
06096Windsor Locks30″24–42″
06101Hartford30″24–36″
06103Hartford30″24–42″
06105Hartford30″24–36″
06106Hartford30″24–36″
06107West Hartford30″24–36″
06108East Hartford30″24–36″
06109Wethersfield30″24–36″
06110West Hartford30″24–36″
06111Newington30″24–36″
06112Hartford30″24–36″
06114Hartford30″24–42″
06117West Hartford30″24–42″
06118East Hartford30″24–42″
06119West Hartford30″24–36″
06120Hartford30″24–36″
06152Hartford30″24–42″
06447Marlborough30″24–36″
06479Plantsville29″24–36″
06489Southington29″24–36″

What this means for your project in Hartford 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 42″ 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 31″ 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; in a climate this cold, 4 feet or more is common for service lines.

Slabs & frost-protected foundations

Frost-protected shallow foundations (IRC R403.3) use the 100-year air freezing index — 990 °F-days here — to size perimeter insulation, letting footings sit shallower than the frost line.

Weather stations used

NOAA weather stationDistance100-yr AFI
Hartford Brainard Fld, CT6 mi938
Middletown 4 W, CT17 mi850
Wigwam Reservoir, CT22 mi1,057
Springfield, MA24 mi955

Nearby counties

Common questions

What is the frost line depth in Hartford County?

About 31 inches in typical soil, based on NOAA's 100-year air freezing index. Across the county's ZIP codes the estimate runs from 29 to 38 inches.

How deep should footings be in Hartford County, Connecticut?

Codes in climates like this commonly require 24 to 42 inches. The Hartford County building department publishes the required frost depth in its adopted code (IRC Table R301.2).

Does frost depth vary within Hartford County?

Yes. Estimates differ by 9 inches between the coldest and mildest ZIP codes, mostly from latitude and elevation. Check your own ZIP below.