Frost and foundations
A joint City of Spokane and Spokane County codes policy sets frost depth at 24 inches below finished grade unless a soils investigation supports a different depth. NOAA's engineering weather data for Spokane records about 72 freeze-thaw cycles a year and a 50-year ground snow load of 42 pounds per square foot. Footings built below the frost line resist heave, but porches, steps, garage aprons, additions on shallow footings and slabs where water collects can lift and crack when the ground freezes.
Snowmelt and basements
Many Spokane homes have basements. When heavy snow melts, water collects against foundation walls, adding pressure and finding its way through cracks, floor-wall joints and window wells. Keep downspouts discharging well away from the house, grade soil away from the foundation, and keep window wells clear. Horizontal cracks and bowing walls are signs of soil pressure that need evaluation. Leaking vertical cracks can usually be sealed with injection, but drainage problems should be fixed first.
Soils and drainage
Spokane draws its drinking water from the Spokane Valley–Rathdrum Prairie Aquifer, which lies in coarse sand and gravel deposits. Soil conditions vary across the area, and some neighborhoods have well-draining gravels while others have finer soils or fill. A foundation contractor or engineer should look at your site's specific soil and drainage rather than assume.
Sump pumps and drain tile
Basement drainage systems and sump pumps are common in the Spokane area. Test your sump pump in fall and before spring melt, keep the discharge line clear and pointed away from the house, and consider battery backup. Where sump water is discharged matters: send it to an approved location, not onto a neighbor's property, and ask your contractor about local rules.
Trees and slopes
Large conifers near the house can affect soil moisture and roots can damage older foundations. On sloped lots, drainage and retaining walls need regular attention.
Before you hire
Ask Spokane foundation contractors what's causing the movement, whether frost or drainage is involved, which repair method they recommend, whether an engineer and permit are required, and what the warranty covers. Use L&I's contractor lookup to check their Washington registration, bond and insurance before you sign.
Tracking cracks
Mark each crack's ends with a pencil and the date, photograph it beside a ruler, and check monthly through a full year. Seasonal frost movement and ongoing settlement look different over time, and the records help any contractor or engineer you consult.
Porches and steps
Front steps and porches on shallow footings often heave with frost and pull away from the house. That gap lets water run against the foundation, so repair or seal it once the cause is fixed.