Short answer: published Seattle-area ranges put a small bathroom job at about $800–$2,400, a crawl space at about $1,500–$5,500, an attic at about $1,200–$4,800 and a basement at about $2,000–$8,500. HomeAdvisor lists a $1,926 average for Bothell mold jobs. Your price depends on the square footage, access, the materials involved and whether the moisture fix is part of the job.
Published price ranges for the Bothell area
These are third-party reference ranges, not our quotes. We include them so you have a yardstick before anyone walks through your house. A written, line-item quote after an inspection is the only number that means anything for your job.
| Job type | Published range | What usually drives it up |
|---|---|---|
| Small bathroom or wall area (under about 100 sq ft) | $800 – $2,400 | Tile removal, growth behind the tub surround, a leaking valve |
| Attic | $1,200 – $4,800; whole-attic jobs with major venting fixes can reach $12,000+ | Square footage, low roof pitch, insulation removal, fan ducting and baffles |
| Crawl space | $1,500 – $5,500 | Height of the space, debris, wet insulation, vapor barrier or encapsulation |
| Basement | $2,000 – $8,500 | Finished walls, carpet and pad, flood cuts, sewage or river water |
| Independent clearance test (post-remediation verification) | $200 – $400 | Number of samples and rooms |
| Indoor air quality test | about $443 average (Seattle area) | Number of samples, lab turnaround |
Sources: Local Service Costs (Seattle, 2026), PNW attic remediation guide, WA contractor directory guide, HomeAdvisor Bothell data. Full links are listed at the bottom of this page.
Why do national averages look so low?
You'll see national figures around $2,400 (SERVPRO and Angi both put the 2026 average near $2,370) and directory ranges as low as $135–$1,592 (Thumbtack). Those numbers blend tiny jobs, like cleaning a window sill or one wall cavity, with real remediation. They also mostly reflect markets cheaper than the Seattle area. A Bothell crawl space with torn vapor barrier, wet insulation and growth across the joists is a different job from cleaning a closet corner, and it's priced that way.
Why did I get quotes from $500 to $20,000?
This is the most common question we hear, and the answer is almost always that the companies aren't quoting the same job.
The $500 quote
Usually a spray, wipe or fog with no containment, no negative air, no removal of moldy material and no clearance test. It's cheap because the hard parts are missing. Mold sprayed in place is still there, and dead mold still causes reactions.
The $20,000 quote
Sometimes justified: a flooded basement with sewage, a whole-house HVAC problem, or full rebuild included. Sometimes it's padded with work that isn't needed, like remodeling a bathroom to fix ceiling mold. Ask what the number includes, line by line.
What actually sets the price
- Square footage affected, and what's growing on it. Drywall, insulation and carpet come out. Framing, joists and subfloor get cleaned in place.
- Access. A 24-inch crawl space or a low-pitch attic takes far longer than a basement wall at standing height.
- The moisture fix. Replacing a vapor barrier, ducting a bath fan outside or fixing a leak adds cost, but skipping it means paying twice.
- Containment. Size, number of zipper doors, and how long negative air has to run.
- Water type. Clean water from a supply line is simpler than gray water or Category 3 water like sewage or river flooding, which means more material comes out.
- Clearance testing, and any retesting if the first round fails.
- Rebuild. New drywall, insulation, paint, trim and flooring are often quoted separately.
What a fair quote includes
A quote you can compare should break the job into lines like these. If a company won't break it out, that tells you something.
| Line item | What it should say |
|---|---|
| Inspection findings | Where the moisture came from, and the areas and square footage affected |
| Containment | Plastic thickness (6-mil), zipper doors, negative air machines ducted outside |
| Removal | Which materials come out (for example "drywall to 24 inches above the floor, baseboards, carpet pad") |
| Cleaning | HEPA vacuuming and damp wiping of what stays, and sanding or blasting of framing |
| Moisture correction | The specific fix, or a note that it's being done by someone else |
| Verification | Independent clearance testing, and what counts as a pass |
| Rebuild | Included, excluded or quoted separately |
Legitimate ways to keep the cost down
- Act early. A bathroom leak caught in a week is a small job. The same leak found at a home sale two years later is not.
- Fix the moisture yourself where it's simple, like cleaning gutters, extending downspouts or reconnecting a bath fan duct, if you're comfortable doing it.
- Check your insurance if a sudden event like a burst pipe caused it. How mold claims work in Washington.
- Phase the work when budgets are tight: the active growth and moisture source first, lower-priority areas later.
- Don't pay for testing you don't need. If you can see the mold and the cause is known, you usually don't need a pre-test to identify the species. You do need clearance testing at the end.
Watch for this: a quote that skips containment and clearance testing to come in cheaper. It may look like a saving, but if the area fails a buyer's inspection later, you pay twice.
How Bothell homes change the math
Most Bothell houses were built between 1970 and 1999, typically on vented crawl spaces, and many have attics with bath fans that were never ducted outside. That's why the crawl space and attic lines are the ones we price most often here. Homes near the Sammamish River, North Creek and Swamp Creek also tend to need a stronger moisture fix in the crawl space, because the ground stays wetter through the winter.
Want a real number for your house? Book an inspection and you'll get a written, line-item range, or start with the crawl space or attic page if you already know where it is.
Sources
- Local Service Costs – Seattle mold remediation costs 2026
- PNW attic mold removal guide (cost and IAQ test averages)
- WA contractor directory – Mold remediation guide (clearance testing cost)
- HomeAdvisor – Mold removal services in Bothell, WA
- CostOf.homes – Mold remediation cost in Seattle
- SERVPRO – How much does mold remediation cost?
- Thumbtack – Mold remediation in Bothell, WA