Spokane, Washington: what the ground under the city is like
Spokane sits in Spokane County, on columbia plateau and palouse. The soil mapped here is predominantly classified well drained — and that classification, not the rainfall total, is what decides how a basement behaves.
17% of the mapped soil area around Spokane is wet enough that the USDA describes it as needing artificial drainage.
Linear extensibility 2.2% — low.
Shallowest annual water table around 160 cm (5.2 ft).
Values are for Spokane County, which is what the soil survey resolves to. Full county report · soil map for a specific address.
The ground under Spokane
Columbia Plateau and Palouse. Deep wind-blown loess over basalt
Deep permeable loess on rolling hills, with basalt below. Water table deep, shrink-swell low. Loess is erodible and can settle under load when saturated, so a broken downspout does more damage here than the climate does.
When it shows up here
| Water | 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 |
The opposite calendar to most of the country: the wet season runs from November to March and the summer is dry. A basement here is tested in January, not in April.
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 Washington
| Reference job | Modelled range |
|---|---|
| Interior drain along two walls + sump pump | $5,850–$12,600 |
| Exterior excavation of one 40 ft wall | $4,400–$12,550 |
| Underpinning on 10 piers | $17,400–$37,100 |
Regional factor for WA: ×1.16. Full cost breakdown for Washington · run your own dimensions.
ZIP codes in Spokane
99201, 99202, 99203, 99204, 99205, 99206, 99207, 99208, 99209, 99210, 99211, 99212, 99213, 99214, 99215, 99216, 99217, 99218, 99219, 99220, 99223, 99224, 99228, 99251, 99252, 99256, 99258, 99260
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.
Questions about Spokane
Is the soil the same everywhere in Spokane?
No. These values describe Spokane County 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 Spokane?
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 Spokane
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Page data updated