Frost Line Depth in Portland, ME: Set Locally (Bangor: 60 in)

No official local value

No official frost line depth is published for Portland.

No verified code nearby. The only verified Maine code we read, Bangor’s, uses 60 in.

Source and how we checked

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

Climate: 144 nights a year at or below 32 °F (NOAA 1991–2020, Portland International Jetport, 5.9 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

60 inBangor, the only verified Maine code
144nights a year at or below 32 °F
94%of nearby soil rated “moderate” for frost action (USDA)

Does Portland have an official frost line depth?

No adopted frost line depth found for Portland in its official documents (checked Oct 2026). No verified code lies near Portland; the only Maine code we verified, Bangor’s, uses 60 in. Ask the building department for Portland’s own number before you dig.

What frost line depth does Portland use for footings under Table R301.2(1)?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Portland building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 60 in (the deepest verified state 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 Portland?

Drawn with the deepest Maine official value (60 in). Confirm Portland’s own depth before you dig.

House or garage footing Deck footing Water service line Fence post

House or garage footing in Portland: dig at least 60 in (152 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Using the nearby official value of 60 in until Portland confirms its own
Project	Depth	Rule
House or garage footing	60 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	60 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	66 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	60 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 Portland?

Average lows are at or below freezing from Nov to Mar. 144 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 15.6 °F.

NOAA 1991–2020 climate normals, Portland International Jetport station, 5.9 mi away, elevation 45 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	15.6	17.3	26	35.4	45.5	55	61.2	59.7	52.1	41	31.7	22.4
High	32.4	35	42.3	53.8	64.2	73.6	79.5	78.7	71.1	59.5	48.4	38.3

Portland has fewer freezing nights than 8 of the 11 other Maine places we track. The Maine median is 162. Coldest: Somerset County; mildest: Knox County.

How likely is the soil in Portland to heave?

Moderate 94%

USDA rates the sampled soil around Portland as 1% low, 94% moderate, 5% high for frost action (main soils: Au Gres, Lyman, Abram).

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

Portland at a glance

Frost line depth: No official local value
County: Cumberland County
Population (2023 est.): 69,104
Mean annual temperature: 47.5 °F
ZIP codes (6): 04019 · 04101 · 04102 · 04103 · 04108 · 04109