Des Moines basements get wet from groundwater on the slope to Puget Sound, from winter condensation and from plumbing leaks, and many of the houses are old enough for worn foundations and finishes. The fix is to stop the moisture, remove moldy porous materials and clean and dry the rest. Call the number on this page to be connected with a local mold remediation company in Des Moines.
Basements on the Des Moines slope
Des Moines climbs from Puget Sound up a broad slope cut by the ravines of Des Moines Creek and Massey Creek, about 16 miles south of Seattle. A house built into that slope, whether in Redondo, Woodmont or Zenith, can have an uphill basement wall soaking up groundwater for months at a time. The housing is fairly mature, with a median build year of 1974, and about 61 percent of housing units are owner-occupied, so a good share of households rent.
What to do now
- Find and stop the water if you can: a leaking hose, a backed-up drain, a flooded window well or seepage at the base of the wall.
- Start drying. EPA says water-damaged areas should be dried within 24 to 48 hours; fans and a dehumidifier help.
- Move boxes, rugs and stored fabric off the floor and away from outside walls.
- Don't paint or caulk over growth; EPA says that doesn't solve the problem.
- Keep anyone with asthma or a weakened immune system out of the area.
- If you rent, notify the landlord in writing. Public Health - Seattle & King County doesn't do mold assessments; it tells tenants to report the unfixed water or maintenance problem to local code enforcement, which in Des Moines is Code Compliance through the city's online complaint form.
What you see and what it usually means
| What you see | Likely cause |
|---|---|
| Damp band along the bottom of the uphill wall | Groundwater or poor drainage outside |
| White crusty deposits on concrete | Efflorescence from water moving through the wall |
| Water beading on walls and pipes in winter | Condensation from humid indoor air |
| Stain spreading from a wall near the laundry | Plumbing or appliance leak |
| Mold on the back of drywall only | Long-term moisture inside the wall cavity |
Cost factors
Angi's Seattle cost guide lists basement remediation at $425 to $2,475, and HomeGuide's 2026 national ranges are $1,500 to $6,000 for a partial job and $6,000 to $15,000 for a whole basement. The biggest swings come from how much finished drywall and flooring has to come out, whether containment and air filtration are needed, how hard the space is to reach, and the rebuild afterward. New walls or plumbing may need a permit from the City of Des Moines Building Division, which reviews plans, issues permits and inspects the work.
Basement Mold Removal questions in Des Moines
I rent a unit with a moldy basement. Who fixes it?
How do I check a basement mold company in Washington?
Is the mold in my basement a health risk?
Will a dehumidifier fix a damp basement?
More mold services in Des Moines
Basement Mold Removal nearby
Sources
- Wikipedia: Des Moines, Washington
- City-Stats: Des Moines, WA
- City of Des Moines: Report a Concern
- City of Des Moines: Building Division
- Public Health - Seattle & King County: Mold (tenants and landlords)
- EPA: Mold Cleanup in Your Home
- Angi: How Much Does Mold Remediation Cost in Seattle, WA?
- HomeGuide: How Much Does Mold Removal and Remediation Cost? (2026)
- RCW 59.18.060: Landlord, Duties
- RCW 59.18.070: Landlord's failure to remedy, Tenant's remedies, Notice
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