The short answer
Mold remediation is priced on how much surface is affected, where it is, and how much building material has to come out. Cleaning mold off exposed attic sheathing is cheaper per square foot than opening a finished wall, which in turn is cheaper than working in a low crawl space. On top of the remediation itself there are up to four other costs: testing, cleaning the heating and cooling system if spores have spread into it, rebuilding what was removed, and fixing the moisture that caused the growth.
That last item is the one that matters most. Mold is a symptom of a water problem. A remediation that does not include the moisture repair is a temporary cleanup. This page is a cost guide, not health advice; if anyone in the house has symptoms they connect with mold, talk to a doctor.
How the calculator works
- Remediation. The affected area is multiplied by a low, typical, and high price per square foot for the location. If the result is below the minimum job charge of $500, $1,000, or $1,500, the minimum applies.
- Rebuild. When selected, new drywall, insulation, and paint are added per square foot of the same area.
- System cleaning, testing, and moisture repair. HVAC cleaning, an inspection with sampling, clearance testing, and the chosen moisture fix are added as flat amounts.
- Location. The local cost level multiplies everything by 0.9, 1.0, or 1.2.
The formula is: total = the greater of (area × price per square foot) and the minimum charge, plus rebuild, HVAC cleaning, testing, and moisture repair, all times the local factor.
Cost assumptions
Professional remediation including containment, air filtration, removal of contaminated material, cleaning, and disposal, national baseline. These are planning ranges compiled from published 2026 remediation cost guides and restoration company price information, not quotes.
| Location | Low per sq ft | Typical per sq ft | High per sq ft |
|---|---|---|---|
| Finished room or bathroom (drywall, behind walls) | $12 | $20 | $30 |
| Basement | $10 | $17 | $25 |
| Attic | $8 | $14 | $22 |
| Crawl space | $10 | $18 | $30 |
| Minimum job charge | $500 | $1,000 | $1,500 |
| Addition | Unit | Low | Typical | High |
|---|---|---|---|---|
| Rebuild: drywall, insulation, paint | Per sq ft | $4 | $7 | $12 |
| HVAC system and duct cleaning | Flat | $2,000 | $4,500 | $9,000 |
| Inspection with sampling | Flat | $300 | $500 | $900 |
| Clearance testing | Flat | $200 | $400 | $700 |
| Minor plumbing leak repair | Flat | $200 | $500 | $1,200 |
| Installed dehumidifier | Flat | $1,200 | $2,000 | $3,200 |
| Crawl space vapor barrier and encapsulation | Flat | $3,000 | $7,000 | $15,000 |
Ten jobs, priced
National baseline.
| Job | Low | Typical | High |
|---|---|---|---|
| 20 sq ft in a bathroom (minimum charge applies) | $500 | $1,000 | $1,500 |
| 50 sq ft in a finished room | $600 | $1,000 | $1,500 |
| 50 sq ft in a finished room, with rebuild | $800 | $1,350 | $2,100 |
| 100 sq ft in a basement | $1,000 | $1,700 | $2,500 |
| 100 sq ft in a basement, with inspection and clearance testing | $1,500 | $2,600 | $4,100 |
| 100 sq ft in a basement, with rebuild, dehumidifier, and both tests | $3,100 | $5,300 | $8,500 |
| 200 sq ft in a basement | $2,000 | $3,400 | $5,000 |
| 300 sq ft of attic sheathing | $2,400 | $4,200 | $6,600 |
| 100 sq ft in a finished room, with HVAC cleaning | $3,200 | $6,500 | $12,000 |
| 400 sq ft crawl space, with encapsulation | $7,000 | $14,200 | $27,000 |
When you can do it yourself
The Environmental Protection Agency's guidance for homeowners draws the line at about 10 square feet, roughly a 3 foot by 3 foot patch. Below that, in most cases, you can do the cleanup yourself. The calculator flags areas under that size.
- Fix the leak or condensation problem first, and dry the area.
- Scrub mold off hard surfaces with detergent and water, then dry them completely.
- Throw away porous materials that are moldy, such as ceiling tiles, carpet, and insulation. Mold grows into them and cannot be fully cleaned out.
- Wear gloves, goggles, and an N95 respirator, and keep the room ventilated.
- Do not paint or caulk over mold. The paint will peel and the mold will continue underneath.
Call a professional when:
- The affected area is larger than about 10 square feet.
- You suspect mold inside the heating and cooling system. Do not run the system, since it can spread spores through the house.
- The water came from sewage or flooding.
- Mold is inside walls, under floors, or above ceilings, where the extent is unknown.
- Someone in the household has asthma, allergies, or a weakened immune system.
What professional remediation includes
- Assessment. Finding the extent of growth and the source of moisture, often with a moisture meter and a thermal camera.
- Containment. Plastic sheeting seals the work area, and fans with high-efficiency filters keep it under negative pressure so spores are not pushed into the rest of the house.
- Removal. Moldy drywall, insulation, carpet, and other porous materials are cut out, bagged, and removed.
- Cleaning. Framing and other solid surfaces are scrubbed, sanded, or blasted, then vacuumed with a high-efficiency filter and wiped down.
- Drying. Dehumidifiers and air movers bring the structure back to a normal moisture level.
- Verification. A visual check, moisture readings, and sometimes independent clearance testing.
Rebuilding the walls and finishes is usually a separate scope, and sometimes a separate contractor. If mold is behind shower tile, the rebuild can become a bathroom renovation; the bathroom remodel cost calculator prices that.
Testing: when it is worth paying for
If you can see mold, you already know you have it, and the EPA says sampling is unnecessary in most such cases. There are no federal standards for acceptable mold levels in a home, so a lab report cannot be judged against an official limit. It can only compare indoor air with outdoor air, or one room with another.
Testing earns its cost in a few situations:
- A musty smell or a history of water damage, with no visible growth to point to.
- A home purchase, a dispute with a landlord or builder, or an insurance claim that needs written evidence.
- Clearance after a large job, to confirm the work area is clean before walls are closed up.
Hire an assessor who does not also sell remediation. A company that profits from the cleanup has a reason to find a large problem. Some states, including New York and Texas, license mold work and do not allow the same firm to both assess and remediate the same job.
Fix the moisture, or pay twice
Mold needs water. The EPA advises drying wet materials within 24 to 48 hours to prevent growth, and keeping indoor relative humidity below 60%, ideally between 30% and 50%. The repair depends on where the water comes from.
| Where the mold is | Usual cause | Typical fix |
|---|---|---|
| Bathroom | Steam with poor ventilation; failed caulk or grout | A properly sized exhaust fan vented outdoors, run after showers; recaulking |
| Attic | Bath or dryer vents discharging into the attic; blocked soffit vents; roof leaks | Extend vents to the exterior, restore ventilation, air seal the ceiling, repair the roof |
| Basement | Groundwater seepage; condensation on cool walls; plumbing leaks | Gutters and grading that move water away, crack sealing, a dehumidifier, drainage if needed |
| Crawl space | Bare soil releasing moisture; humid outside air through vents | A sealed vapor barrier, drainage, and a dehumidifier or full encapsulation |
| Around windows and exterior walls | Condensation; leaks at flashing | Flashing repair, better insulation, lower indoor humidity |
| Under sinks, behind appliances | Slow supply or drain leaks | Plumbing repair and replacement of wet cabinet or wall material |
Insurance
Homeowners policies generally cover mold only when it follows directly from a sudden and accidental event that the policy covers, such as a burst pipe or a washing machine hose that fails, and only when the damage was dealt with promptly. Mold from a slow leak, high humidity, deferred maintenance, or groundwater is typically excluded, and flood damage is not covered by a standard policy at all. Where mold is covered, there is often a separate, lower limit for it. Report water damage right away, photograph everything before cleanup, and keep damaged materials until the adjuster has seen them if you can. Our step-by-step guide to insurance claims covers the process, and the home insurance calculator checks your dwelling limit.
How to compare remediation quotes
Get three written quotes and check that each one states:
- The affected areas and square footage, and how the extent was determined.
- The containment and air filtration that will be set up.
- Which materials will be removed and which will be cleaned in place.
- How the moisture source will be corrected, and by whom.
- Whether rebuilding is included.
- How the result will be verified, and whether an independent party does the clearance.
- The company's certification, state license where one is required, and insurance that specifically covers mold work.
- The warranty, and what conditions void it.
Be wary of anyone who diagnoses "toxic mold" on sight, recommends fogging or spraying as the whole solution, or offers a free test tied to their own remediation. Chemicals do not remove mold from porous materials, and dead mold left in place can still cause allergic reactions. For vetting companies, see our guide to finding the right contractors.
Keep the paperwork
Many states require sellers to disclose known mold or water problems, and a buyer's inspector will often find the signs anyway. A documented, professionally completed repair is far less worrying to a buyer than an unexplained stain. Keep the inspection report, lab results, the remediation contract and invoice, the clearance letter, receipts for the moisture repair, and dated photos before, during, and after the work.
What the estimate leaves out
The calculator does not price major water damage restoration, structural drying after a flood, sewage cleanup, roof replacement, foundation waterproofing or drainage systems, replacement of cabinets, flooring, and tile, cleaning or replacing contaminated furniture and belongings, temporary housing, or asbestos and lead testing that may be required before demolition in older homes. It does not subtract anything an insurer may pay.
Cost assumptions last reviewed November 2026. See our calculator methodology.