How Mold Remediation Works

You found mold, or you can smell it and cannot find it. Either way, the fix is well understood. Professional mold remediation removes the growth safely, keeps spores from spreading to the rest of the house, and deals with the moisture that let it grow in the first place.

Mold removal and mold remediation are not the same thing

Mold removal usually means wiping or scrubbing off the mold you can see. Mold remediation is the complete job. The area is sealed off, the air is filtered, moldy materials that cannot be cleaned are taken out, everything left is cleaned and dried, and the source of the moisture is found. Skipping any of those steps is why mold so often returns a few months after a quick cleanup.

Not every spot needs a professional. The EPA says a patch smaller than about 10 square feet, roughly 3 feet by 3 feet, can usually be cleaned by a homeowner. Larger areas, mold inside walls or ducts, and mold after flooding or a sewage backup are the jobs that call for remediation.

How mold remediation works, step by step

1. Inspection and a written plan

We look at the mold you can see, take moisture readings around it to find how far the dampness reaches, and check the likely sources such as a leaking pipe, a wet foundation wall or a bathroom fan that vents into the attic. You get a written scope and price before any work starts. Learn about mold inspection.

2. Containment

The work area is closed off with plastic sheeting and taped seams so spores stay where they are. A HEPA air scrubber, a machine that filters fine particles out of the air, runs the whole time and keeps the work area at slightly lower air pressure than the rest of the house, so air flows in rather than out.

3. Removal

Porous materials that mold has grown into, such as drywall, ceiling tiles, insulation and carpet, are cut out, bagged inside the containment and carried out sealed. The EPA notes these materials often cannot be cleaned well enough to save.

4. Cleaning and drying

Hard materials like wood framing, joists and concrete are cleaned in place, HEPA vacuumed and dried. Dehumidifiers and fans bring the area back to normal moisture levels before anything is closed up again. The EPA does not recommend bleach as a routine step, and we do not paint over mold to hide it.

5. Final check and the moisture fix

Before the containment comes down, the area is checked for visible mold and moisture. You get a plain explanation of what caused the problem and what it will take to keep the area dry, whether that is a dehumidifier, a repaired leak, better drainage outside or a bathroom fan routed outdoors.

What is included

What affects the price

Most homes pay $1,200 to $3,800 for professional mold remediation, and national cost guides put typical work at $10 to $30 per square foot. The price is driven by a few things. For full ranges and a quick estimate, see our mold remediation cost guide.

After the work

Mold comes back when the moisture comes back. Keep indoor humidity below about 60 percent, run a dehumidifier in damp basements in summer, fix leaks quickly, and dry anything that gets wet within 24 to 48 hours. If you ever notice the musty smell again, call before it spreads.

Common questions about remediation

Do I have to leave the house?

Usually not for a contained job. The work area is sealed off and filtered. People with asthma, allergies or weak immune systems may want to stay elsewhere during the work, and we will tell you if a job is large enough that leaving makes sense.

How long does it take?

A small area is often done in a day. A basement or attic usually takes two to five days including drying time.