Bothell Crawl Space Repair

Bothell is mapped in two soil survey areas, and the Alderwood soils common across the metro appear under the same names in both. Alderwood gravelly sandy loam on three slope classes and Alderwood-Urban land complex on two cover at least 45.2% of the mapped area between them, counting only the twelve largest map units, and the survey rates all of it moderately well drained. Kitsap silt loam adds 13.5%, and Everett very gravelly sandy loam, rated somewhat excessively drained, 6.0%.

The wetter ground is where Bothell differs. Poorly drained soils cover 11.3% of the mapped area, very poorly drained 3.8% and somewhat poorly drained 1.6%. The two largest wet-rated map units are both silt loams rated poorly drained, Snohomish silt loam (3.4%) and McKenna gravelly silt loam on 0 to 8 percent slopes (3.0%); the rest of the wet-rated area is split among smaller units. On those units the rating itself describes soil that drains slowly or stays saturated, so water can reach a crawl space from below as well as from the roof.

That changes the order of questions. If the crawl space is wet each winter with the gutters and downspouts sound, ask whether water is rising through the soil, and if it is, a drain and sump may be the answer rather than a thicker ground cover. An interior drainage scope runs $4,025 to $7,175 on this site’s cost guide, before sales tax. The survey still maps units, not lots, so the soil under a particular house is found by looking at it. What crawl space drainage covers sets out the parts.

Bothell is one of the four cities King County lists along the 14 miles of the Sammamish River. In 2019 the Washington Geological Survey published a lidar-based landslide inventory of about 1,480 square miles of western King County, with the City of Bothell added to it. It mapped 2,838 landslides and 1,251 fans, and found the highest densities along the Puget Sound bluffs and the river corridors. The announcement this site read gives no Bothell count, and neither the report’s maps nor Bothell’s own critical-area maps have been read here.

The soil map does show slopes: Kitsap silt loam on 15 to 30 percent slopes covers 7.7% of the city and Alderwood gravelly sandy loam on 15 to 30 percent slopes another 4.5%. On a lot near the river or on one of those slopes, ask the Permit Center whether the parcel is mapped as a hazard area before a drain or a sump discharge is designed, and ask any contractor where the collected water will end up. A trench outside the house needs a utility locate first, too: Washington requires the excavator to give notice through the one-number locator service at least two full business days, and no more than ten, before digging.

The 1980s were Bothell’s biggest decade of building, with 4,023 housing units, followed by the 2010s with 3,778, the 2000s with 3,165 and the 1990s with 3,000. Since 2020 the Census counts another 1,052. Everything built before 1970 comes to 2,902 units, 14.1% of the city.

On a newer house on wet-rated ground, the useful records are the builder’s. Drawings or a permit file may show whether a drain was installed around the foundation and where it discharges, and that is worth finding before paying anyone to install another. On a house from the 1980s or 1990s, the materials have had thirty or forty winters: check that the ground cover is still continuous and lapped, that insulation is still against the subfloor, and that a sump, if there is one, still runs and discharges where it should. A sump pump that runs constantly explains what an always-on pump can mean.

The city line, not the county line, decides who issues permits. Building permits anywhere in Bothell come from the Permit Center in the city’s Community Development department, through MyBuildingPermit.com, and the city says electrical permits are obtained through L&I; Bothell is not on L&I’s list of cities that run their own. This site has not read which crawl space work Bothell exempts from a building permit.

Sales tax follows the county. For October 1 to December 31, 2026 the Department of Revenue lists Bothell in King County at 10.3% and Bothell in Snohomish County at 10.5%, so the rate on a job depends on the address. Either applies to the whole contract price, and the cost guide’s ranges are before it. King County’s Housing Repair Program, which lends to income-qualified owner-occupiers in the county outside Seattle and Bellevue, reaches only the King County side.

Radon figures are published by county too. Both counties are in the EPA’s lowest radon zone. Of the laboratory tests the Department of Health received in 2025, 5% of King County’s (63 of 1,177) and 3% of Snohomish County’s (4 of 155) were at or above 4 pCi/L. Those are tests owners chose to send, and Snohomish’s is a small count, so neither side should read its figure as a reason not to test. The department counts a crawl space vapor barrier among simple steps that reduce radon, and a test in the living space before and after sealing a crawl space is the way to know.

The nearest published NOAA station to Bothell’s Census internal point is Seattle’s Sand Point station, 6.4 miles away, with a 1991–2020 annual normal of 37.82 inches. The Everett airport, 9.9 miles away, records 33.37 inches, and Monroe, 10.9 miles away, 50.77 inches. No other city of the nineteen is as close to Monroe, so the wetter record behind Bothell’s 17.4-inch spread is not a distant gauge at the edge of the 15-mile circle.

The difference shows in heavy days as well as totals. Monroe averages 7.3 days a year with an inch of rain or more, against 4.2 at Sand Point and 2.5 at the Everett airport. On wet-rated ground, a day like that is when a crawl space shows whether its drainage keeps up, so a look under the house after one is worth more than a dry-season inspection.