Frost Line Depth in Gresham, OR: 18 in (Oregon rule)

State-set value

18in

46 cm · 1 ft 6 in

18 in (Oregon rule)

Set by the state: Oregon Residential Specialty Code Table R301.2(1), Multnomah County.

Source and how we checked

Gresham does not publish its own value; the state rule applies.

Document: codes.iccsafe.org

Climate: 28 nights a year at or below 32 °F (NOAA 1991–2020, Portland Troutdale Airport, 3.7 mi).

Checked Oct 2026. Report a correction

Footings Deck Water line Fence post

0 of 1nearby verified codes use the same depth
28nights a year at or below 32 °F
64%of nearby soil rated “low” for frost action (USDA)

How deep is the frost line in Gresham?

Oregon sets the frost footing depth for Gresham at 18 in (46 cm). Footings, piers and other permanent supports must reach at least this depth (IRC R403.1.4.1).

Who sets the frost line depth in Gresham?

Oregon writes this depth into its statewide residential code, so Gresham’s building department enforces the state’s number rather than setting its own. See how Oregon sets frost line depth.

How deep do footings, decks and water lines need to be in Gresham?

House or garage footing Deck footing Water service line Fence post

House or garage footing in Gresham: dig at least 18 in (46 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).

Minimum depths in Gresham with a 18 in frost line
Project	Depth	Rule
House or garage footing	18 in	Below the frost line and at least 12 in deep (IRC R403.1.4)
Deck footing (attached)	18 in	Below the frost line and at least 12 in deep (IRC R507.3)
Water service line	24 in	6 in below the frost line and at least 12 in deep (IRC P2603.5)
Fence post bottom	18 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 Gresham?

Gresham never averages a low below freezing. 28 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 37.2 °F.

NOAA 1991–2020 climate normals, Portland Troutdale Airport station, 3.7 mi away, elevation 29 ft.

Monthly temperatures as a table

°F	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Low	37.3	37.7	40	43.2	48.9	53	56.8	56.9	52.4	46.4	41.6	37.2
High	46.7	51	56.7	61.7	68.9	74	81.6	82.3	76.4	64.1	52.6	46

Gresham has fewer freezing nights than 20 of the 22 other Oregon places we track. The Oregon median is 54. Coldest: Deschutes County; mildest: Lincoln County.

What frost line depth do towns near Gresham use?

One official code near Gresham is verified.

Official frost line depths near Gresham
Place	Verified frost line	Distance
Marion County	12 in	42 mi away

How likely is the soil in Gresham to heave?

None 36%Low 64%

USDA rates the sampled soil around Gresham as 36% none, 64% low for frost action (main soils: Cascade, Wollent, Urban land).

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

How do you confirm the frost line before you dig in Gresham?

Call 811 at least a few working days before you dig, so buried lines are marked.
Confirm the frost line depth with the Gresham building department.
Ask whether your project needs a permit (decks, larger sheds and footings usually do).
Dig below 18 in unless the building department tells you otherwise.
Book the footing inspection before you pour concrete.

Gresham at a glance

Frost line depth: 18 in (Oregon rule)
County: Multnomah County
Population (2023 est.): 110,685
Mean annual temperature: 54.7 °F
ZIP codes (6): 97024 · 97030 · 97080 · 97230 · 97233 · 97236