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Mold Remediation in Seattle, WA
More than 10 square feet of mold growth calls for professional help under Public Health — Seattle & King County guidance, and wet-season moisture entering basements and crawlspaces routinely gets homes there. One call reaches vetted local mold-remediation pros.
Recent floods · Seattle
No recent flood events near Seattle — see the live board.
Seattle's 426,090 housing units absorb 37.7 inches of precipitation a year, and mold follows that water indoors. Federally declared flooding, landslides and mudslides hit King County in 2024, 2025 and 2026 — three straight years of saturation events, part of the 17 flood declarations among the county's 35 total. Public health guidance for the area ties that seasonal moisture to leaks and to water entering basements and crawlspaces, the conditions mold growth needs.
Mold risk in Seattle
37.7"
average annual precipitation (NOAA)
83%
of King County's 35 declared disasters were floods, hurricanes or storms (FEMA)
2026
most recent flood/storm declaration: Severe Storms, Straight-Line Winds, Flooding, Landslides, and Mudslides (FEMA)
Sources: FEMA OpenFEMA — federally-declared disaster history (county FIPS 53033) · NOAA NCEI — 1991–2020 Climate Normals (SEATTLE PORTAGE BAY, WA US)
What makes Seattle a mold-prone city
Mold in the city is a water-event problem before it is an air problem. Flooding accounts for 17 of King County's 35 federal disaster declarations, and the exposure is concentrated: during the 2009 Howard Hanson Dam flood-risk emergency, FEMA estimated potential property damage to homes and businesses in the Green River floodplain at $2 billion to $3 billion. Public Health — Seattle & King County advises flushing indoor air two to three times a day and calls for professional help once mold covers more than 10 square feet.
Tenure and building maintenance shape who acts. About 58.1 percent of the city's housing units are renter-occupied, so moisture problems often surface through the Rental Registration and Inspection Ordinance (Seattle Municipal Code Chapter 22.210), under which registered rental properties are inspected at least once every 5–10 years and inspectors look for holes or visible leaks in the roof or walls. Under RCW 59.18.060, landlords must give tenants Department of Health-approved information on indoor mold hazards.
Washington sets no licensing bar for the work itself: the state Department of Health states there are no specific certification requirements for performing mold or water-damage restoration, and that anyone can call themselves a mold remediation specialist. Vetting therefore falls to the property owner — confirm voluntary certification, moisture documentation, and a repair of the water source, not just the visible growth. The national mold remediation guide covers what that scope should include.
Mold remediation rules & licensing
Washington sets no license specifically for mold remediation. The state Department of Health states there are no certification requirements for performing mold or water-damage restoration, so anyone may advertise as a remediation specialist. What binds the work is general rather than mold-specific: contractors must register with the Department of Labor & Industries, and renovation that disturbs building materials triggers the Puget Sound Clean Air Agency's asbestos survey and notification rules. City enforcement is condition-based — the Housing and Building Maintenance Code and the rental inspection program target visible moisture and weathertightness, treating mold as evidence of a water problem rather than as a regulated substance carrying its own permit.
| Permit / inspection | When it applies |
|---|---|
| Washington State Department of Health — mold remediation licensing | State level. Washington requires no license or certification specific to mold remediation. The health department states plainly that there are no certification requirements for performing mold or water-damage restoration work, and that anyone can call themselves a mold remediation specialist without specialized training or credentials. Voluntary IICRC training and certification fills the gap and is commonly requested by insurers. Neither the county nor the city adds a mold-specific license on top. |
| Contractor Registration — Washington State Department of Labor & Industries | State level, and the only credential a remediation firm working in the area is legally required to hold. All construction contractors must register with Labor & Industries, which means a $30,000 surety bond for general contractors or $15,000 for specialty contractors, plus liability coverage of either $200,000 public liability and $50,000 property damage or a $250,000 combined single limit. The application fee is $150.20. |
| Asbestos Survey and Notification — Puget Sound Clean Air Agency, Regulation III | Regional level, covering the Puget Sound region. Before renovation that disturbs building materials, an AHERA-certified building inspector must survey for asbestos; only owner-occupied single-family homes may be surveyed by the owner. Survey results must be shared with workers and kept on site. Friable asbestos must be removed by a certified asbestos abatement contractor, and a notification plus filing fee must be submitted before removal begins, with a possible 10-day waiting period. Friable projects under 10 linear feet or 48 square feet are exempt from notification. |
| Housing and Building Maintenance Code — Seattle Municipal Code Chapters 22.200–22.208 | City level, applying to all buildings in the city. The code sets minimum maintenance standards covering structural integrity, heat, ventilation, electrical equipment, and sanitation, and holds owners responsible for keeping buildings weathertight and watertight. It contains no mold clause. The Department of Construction and Inspections enforces the underlying water or ventilation defect on complaint, which is why housing complaints are framed around the moisture source rather than the growth itself. |
| Rental Registration and Inspection Ordinance — Seattle Municipal Code Chapter 22.214 | City level, rental housing only. Landlords must register every rental unit, from single-family houses to large apartment buildings, and registered properties are inspected at least once every 5 to 10 years by either a qualified private rental housing inspector or a city inspector. Inspections confirm compliance with basic housing maintenance standards. Complaint-driven enforcement is not handled here — it runs through the Housing and Building Maintenance Code instead. |
| Permit exemption for minor repairs — Seattle Department of Construction and Inspections | City level. Minor repairs or alterations valued at $6,000 or less in any six-month period require no permit, measured by the fair market value of labor and materials even when the owner does the work. The exemption does not reach anything affecting load-bearing supports, the building envelope, egress, light, ventilation, or fire resistance, which must be permitted regardless of cost. Drying and finish replacement often falls under the threshold; the envelope or structural repair behind the growth does not. |
| Mold information requirement — RCW 59.18.060, Residential Landlord-Tenant Act | State level, binding on landlords in the area. At the time a lease or rental agreement is signed, a landlord must give new tenants health department information on the hazards of indoor mold exposure and how to control mold growth in the unit, provided individually in writing or posted in a visible, public location at the property. Accepted materials include the health department's mold questions-and-answers sheet and the EPA brief guide on mold, moisture, and homes. |
Mold disclosure & remediation standards
- Seller Disclosure Statement (Form 17) — RCW 64.06.020
- State level. Sellers of improved residential property must deliver a completed disclosure statement within five business days of mutual acceptance. It asks whether the basement has flooded or leaked, whether the roof has leaked within the last five years, and whether flooding, standing water, or drainage problems affect the property. Buyers get three business days from delivery to rescind the agreement in writing.
- Landlord duty to commence remedial action — RCW 59.18.070
- State level. Once a tenant gives written notice of a defective condition, the landlord must begin repairs within 24 hours if the defect cuts off hot or cold water, heat, or electricity or is imminently hazardous to life; within 72 hours for a major plumbing fixture, refrigerator, or range and oven; and within 10 days in all other cases. Moisture defects such as roof and plumbing leaks generally fall in the 10-day tier.
- Renters, Landlords, and Mold — Washington State Department of Health
- State level. The health department splits the duty: landlords maintain the unit and fix building problems such as water leaks and ventilation or heating defects that lead to moisture, while renters operate heating and ventilation to reduce condensation and must notify the landlord promptly in writing of leaks or moisture buildup. The department publishes the Mold Questions and Answers booklet, in English and Spanish, as approved notification material.
- Minimum housing standards — Seattle Municipal Code Chapter 22.206
- Local level. The Department of Construction and Inspections enforces minimum maintenance standards covering roofs, floors, walls, chimneys and foundations, plus heating, ventilation, light and sanitation. Mold itself is not the citable condition; the moisture source is. A tenant complaint can trigger a housing inspection, and a unit that falls below the standards can draw a notice of violation subject to fines and penalties.
Local mold notes
- Mold assessments — Public Health — Seattle & King County — The county health department states that Public Health does not conduct mold assessments. It refers residents who want a professional evaluation to the American Industrial Hygiene Association's consultant directory, and offers a mold assistance request form for educational help rather than inspection. Its published role is prevention guidance: fixing leaks, controlling condensation, and reserving professional remediation for larger growth.
- Flood recovery health guidance — Public Health — Seattle & King County — After a flood the county health department publishes its recovery guidance in 27 languages, including a sheet titled "What to wear before entering a home or building with mold damage" and a basement cleanup guide issued in 7 languages. The same page carries the CDC's "Homeowners and Renters Guide to Mold Cleanup After Disasters" in English, Spanish, and Vietnamese. The set is aimed at residents re-entering a flooded structure and pairs mold with lead, asbestos, and contaminated soil as the post-flood hazards to plan for.
- Complaint-based housing inspections — Seattle Department of Construction and Inspections — Moisture reaches code enforcement here through tenant complaints, not routine patrols. SDCI describes its housing inspections as complaint-driven and lists proper ventilation and moisture control to prevent mold among the conditions an inspector evaluates on site. The published sequence runs complaint, inspector assignment, on-site evaluation, a Notice of Violation or citation setting correction requirements and a deadline, owner repairs, reinspection, then case closure. That makes a written complaint the practical trigger for any city record of a moisture defect in a rental.
- Post-flood cleanup instructions — King County flood recovery guidance — County cleanup instructions treat some flood-soaked assemblies as unsalvageable rather than dryable: wall-to-wall carpet and padding saturated by floodwater is to be discarded because it cannot be cleaned and dried quickly enough to stop mold and bacteria growth. For woodwork and paneling the county specifies an alkali wash of 5 tablespoons of washing soda or trisodium phosphate per gallon of water, and for mold that has penetrated further, 4 to 6 tablespoons of trisodium phosphate plus three-quarters of a cup of 5.25 percent household bleach per gallon.
- Tenant dispute referrals — Public Health — Seattle & King County — For renters in a mold dispute the county health department's own page routes them outward, listing the King County Bar Association Housing Justice Project, the Northwest Justice Project, the Tenants Union of Washington State hotline, and local building and code enforcement officials as the bodies that investigate water and maintenance issues. It also tells tenants to notify a landlord in writing about leaks or moisture, which is what creates the dated record later relied on.
Cleanup & recovery services nearby
- NW Dumpsters — Locally owned, minority-owned roll-off rental — 20-, 30- and 40-yard containers plus lidded units and a 10-yard rock box for concrete, delivered seven days a week for demolition and cleanout debris.
- Big Mike's Recycle — Ballard-based waste hauler operating since 2020 — 10- and 20-yard dumpsters, junk removal and curbside bulk collection with LEED-certified disposal for gut-out debris.
- Seattle Tree Care — Arborist firm working the area and the Eastside since 2007 — a team of 12 ISA Certified Arborists on call around the clock for storm-damage cleanup, hazardous removals and root-zone excavation.
- Ballard Tree Service — Family-run tree service since 1990 with three ISA Certified Arborists — 24-hour emergency line for fallen trees, plus pruning, planting and stump grinding.
- Seattle Sodo Storage (The H.O. Seiffert Company) — Fourth-generation family business founded in 1901 and in storage since 1987 — climate-controlled units among more than 1,500 across three locations, for household contents pulled out during repairs.
- ACE Glass LLC — Glass and window shop with 24/7 emergency board-up — plywood over openings broken by storms, accidents or vandalism to keep rain and intruders out until glass is replaced.
By the numbers
- Median year city buildings were built — Older than the Washington median of 1978 and the national median of 1968; about 23 percent of housing units date to 1939 or earlier.
- 1956