Anchorage, Alaska: what the ground under the city is like
Anchorage sits in Anchorage Municipality, on alaska: permafrost and frost-susceptible ground. The soil mapped here is predominantly classified well drained — and that classification, not the rainfall total, is what decides how a slab foundation behaves.
Linear extensibility 4.2% — moderate.
42% of the mapped soil area around Anchorage is wet enough that the USDA describes it as needing artificial drainage.
Shallowest annual water table around 105 cm (3.4 ft).
Values are for Anchorage Municipality, which is what the soil survey resolves to. Full county report · soil map for a specific address.
The ground under Anchorage
Alaska: permafrost and frost-susceptible ground. Glacial, alluvial and organic soils, discontinuous permafrost, deep frost penetration
A different physics from the rest of the country. Frost heave and thawing permafrost move foundations far more than shrink-swell does, and a heated basement is itself a hazard where permafrost is present, because the heat thaws the ground it sits on. Local engineering practice, not national rules of thumb, governs here.
When it shows up here
| Slab moisture | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ground movement | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
Water peaks with the March–April thaw, when frozen ground stops absorbing and meltwater plus spring rain arrive together. If a basement here leaks once a year, that is when.
Climate pattern for this physiographic region, not a forecast for your house and not from the soil survey. It answers a question homeowners actually ask: when does this show up.
What repairs cost in Alaska
| Reference job | Modelled range |
|---|---|
| Slab foundation lifted and stabilised on 12 piers | $23,400–$49,900 |
| Two slab cracks injected + regrading around the perimeter | $2,600–$8,700 |
| Engineer's report plus buried downspout discharge | $1,700–$5,700 |
Regional factor for AK: ×1.30. Full cost breakdown for Alaska · run your own dimensions.
ZIP codes in Anchorage
99501, 99502, 99503, 99504, 99507, 99508, 99510, 99513, 99515, 99516, 99517, 99518, 99519, 99530, 99695
Soil does not stop at a city boundary, and neither does this data — every ZIP code above resolves to the same county soil survey. For the individual survey polygons around one address, use the soil map.
Other places in Anchorage Municipality
Questions about Anchorage
Is the soil the same everywhere in Anchorage?
No. These values describe Anchorage Municipality as a whole, which is the unit the soil survey publishes. Within a city, map units change over a few hundred metres — the soil map draws the actual polygons around a point and is the honest answer for one address.
Which contractor should I call in Anchorage?
We do not rank or recommend individual firms and we are not one. What this page is for is knowing which kind of work the ground here points to before anyone quotes you, and which claim to check. If you want quotes, the form below passes your request to the named networks.
Does this replace an inspection?
No. It tells you what the ground is; an inspection tells you what your building is doing on it. The useful order is: read this, print the brief for your county, then have someone look.
Get quotes in Anchorage
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Page data updated