Read This First
Every figure on this page is a planning range for the south-central Wisconsin market, not a quote. Nobody can price a mold job they have not seen, and anyone who gives you a firm number over the phone before looking is guessing or quoting for something other than the job you have.
The single thing that moves a price most is not the size of the stain. It is the size of the wet area, how long it has been wet, and whether what is wet can be dried in place or has to come out. A two-foot patch of growth on a wall that has been wet for three years is a bigger job than a four-foot patch that got wet last Tuesday.
A number well below the others generally means one of three things has been left out: the containment, the removal of porous material, or the independent clearance test at the end. Ask which. All three are the parts that make the difference between the problem being gone and the problem being painted over.
Get a read on your own situation
Describe what you are seeing and the age of the building. You will get the likely range and an honest view on urgency.
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What the Work Costs in Janesville
Ranges below assume a normal residential property in Janesville or Rock County, with reasonable access and no unusual contamination. They exclude reconstruction unless stated.
| Work | Typical range | What it covers |
|---|---|---|
| Mold inspection | $250–$600 | Thermal imaging, moisture metering, written findings. Where most projects should start. |
| Air sampling package | $250–$550 | Two indoor samples plus an outdoor control, accredited lab analysis. |
| Small contained area | $500–$1,500 | One wall section, a closet, behind a water heater. Roughly 10–30 sq ft. |
| Single room | $1,200–$3,800 | Containment, removal, drying, clearance. |
| Finished basement | $4,000–$12,000 | Wall removal, drying, clearance. Excludes rebuilding. |
| Unfinished basement | $1,200–$3,500 | Clean, treat, dry. No finishes to remove, which is why it is cheap. |
| Attic remediation | $2,800–$7,500 | Cleaning, treatment and re-insulation. Ventilation correction usually extra. |
| Crawl space with encapsulation | $3,500–$11,000 | Removal, vapor barrier, sealing, dehumidification. |
| Flooded basement | $2,500–$8,000 | Extraction, removal of wet material, structural drying. Before mold work is priced. |
| Burst supply line in a wall | $1,500–$6,000 | Depends almost entirely on how long it ran before it was found. |
| Rim joist remediation | $800–$2,500 | The coldest wood in a Wisconsin basement, and rarely inspected. |
| HVAC coil and duct cleaning | $600–$1,800 | Where the air handler is distributing a local problem. |
| Encapsulation coating | $1,000–$3,500 | After cleaning, not instead of it. Attic sheathing or crawl framing. |
| Dry fog treatment | $1,200–$4,500 | A supplementary step. Never a substitute for removing wet material. |
| Independent clearance test | $400–$900 | Should not be the firm that did the work. |
| Radon test / mitigation | $150 / $900–$2,200 | Rock County is an EPA Zone 1 county. Cheap to check while the basement is open. |
Prices shown are examples only. For an accurate quote for your specific situation, call (608) 724-1919 — free consultation with a specialist.
What Actually Moves the Number
How long it has been wet
This is the big one. Material wet for two days is usually dried and kept. Material wet for two months is removed. The difference between those two outcomes on the same wall can be a factor of five in price, and it is decided entirely by when somebody noticed.
Whether the water is still arriving
Remediation that does not correct the moisture source is money spent on a repeat performance. If the cause is a grading problem, a failed sump or a bath fan discharging into the attic, that correction is part of the real cost even when it appears on a different invoice. A quote that says nothing about the water is incomplete.
What has to come out and be put back
Removing a finished basement wall is cheap compared with rebuilding it. Most of the quotes people compare are for the removal half only, and the reconstruction arrives later as a separate number. Ask explicitly which half you are looking at.
Access
A crawl space you can sit up in costs less to work in than one with eighteen inches of clearance. An attic with a proper hatch costs less than one reached through a closet ceiling. None of this is negotiable, but it explains differences between apparently similar jobs.
Containment requirements
A small job in an empty basement needs less containment than the same square footage in an occupied house with a forced-air system running through it. Occupied commercial space is more again.
Where You Can Reasonably Spend Nothing
Some of what gets quoted does not need to be bought at all, and it is worth knowing which.
- Under about ten square feet of surface growth on a hard, non-porous surface — the EPA's own guidance is that a homeowner can generally handle this. Detergent and water, dry it properly, and correct whatever wet it.
- Seasonal basement condensation — if the damp appears in July and disappears in January, the answer is air sealing and a correctly sized dehumidifier, not a remediation crew. That is a few hundred dollars of equipment, not a few thousand of labor.
- Testing where you can already see it — if the growth is visible and the water source is known, a lab result changes nothing about what has to happen next.
- Whole-house fogging as a first move — if wet porous material is still in the building, fogging it is treating the symptom.
Insurance, Briefly
A Wisconsin homeowners policy generally excludes mold as such, and generally covers sudden and accidental water — a burst supply line, an appliance failure. Long-term seepage, groundwater and surface flooding are normally excluded, with flood covered only by a separate NFIP or private flood policy. Many policies carry a capped mold endorsement, often in the $5,000 to $10,000 range, which is frequently less than a finished basement job. The insurance article goes through it properly.
How to Compare Two Quotes Honestly
- Put them on the same scopeDoes each include containment, negative air, removal of porous material, drying to a documented target, and clearance? If not, you are comparing different jobs.
- Check who verifies the resultClearance testing by the firm that did the work is a conflict of interest, not a check.
- Find the moisture correctionIf neither quote mentions why the material was wet, neither has priced the actual problem.
- Ask what happens if it failsWhat the warranty covers, for how long, and what voids it.
- Verify the paperworkLiability and pollution liability insurance, IICRC S520 certification, and a Wisconsin Dwelling Contractor credential for any rebuild.
Cost Questions We Are Asked Most
Because the price is set by things that cannot be seen over the phone: how far the wet area extends behind the finish, how long it has been wet, what the material is, and whether the water is still arriving. What you can get on a call is the range, which of the rows in the table above your situation probably falls into, and whether it sounds like something that needs attention this week. That is genuinely useful and it costs nothing. A firm number before an inspection is either a guess or a foot in the door.
Generally yes, and noticeably so against Chicago. Labour rates in south-central Wisconsin sit below both metros, and the ranges on this page reflect that. It is worth knowing when you read national cost guides, most of which are averaged across markets that include the coasts and read high for this area. It cuts the other way too: a very low quote here is low against an already-modest local market, which is worth a question rather than a celebration.
Barely. Two things matter far more. The first is how far the moisture extends past the visible growth — on a finished basement wall the wet area behind the board is routinely several times the stained area on the face of it. The second is how long it has been wet, because that decides whether material is dried or removed. A moisture meter and a thermal camera answer both in an hour, which is what the inspection is for.
Two or three is sensible, provided you make them quote the same scope. The common failure is collecting three numbers for three different jobs and picking the lowest, which reliably selects the one that left the most out. Write down the scope you want priced — containment, removal of porous material, drying to a documented target, independent clearance — and give the same sheet to each. The numbers then mean something.
Rebuilding a stripped finished basement typically runs from around $25 to $60 per square foot depending on the specification, so a moderate basement can add five figures. This is why the order matters: correct the water, do the remediation, verify it, and only then rebuild — and rebuild with an assembly that will not repeat the failure. Rigid foam against the masonry rather than a stud wall tight to it, and no paper-faced board below grade.