Mold remediation that starts with the water behind it

Is it a job for you or for a contractor?

The EPA's guide to mold and moisture at home says that if the moldy area is less than about 10 square feet, roughly a 3 foot by 3 foot patch, a homeowner can usually handle the cleanup. Larger areas, mold inside walls or ductwork, or mold after sewage or floodwater call for a contractor.

For a small patch, follow the EPA's advice: scrub hard surfaces with detergent and water, dry them completely, and throw away absorbent materials such as ceiling tiles and carpet that have grown mold. The EPA does not recommend bleach as a routine part of mold cleanup, and warns never to mix bleach with cleaners that contain ammonia.

Growth that keeps returning is another reason to call a contractor. So is any situation where you are not sure what the moisture source is. When you hire, the EPA suggests checking references and asking the contractor to follow the EPA's own remediation guidance or other professional guidelines.

What the S520 standard aims for

The IICRC's S520 standard for professional mold remediation describes three conditions. Condition 1 is the normal background of mold spores found in any house. Condition 2 is an area contaminated with settled spores that blew in from elsewhere. Condition 3 is an area with actual mold growth. The goal of remediation in that standard is to bring Condition 2 and 3 areas back to Condition 1, which is a more honest target than "zero mold", because spores are part of normal indoor air everywhere. Any company promising to make a house free of mold is promising something no one can deliver.

How mold remediation is done

1. Find the moisture. A leaking pipe, a roof or window leak, a damp crawl space or condensation on a cold surface. Without fixing it, any cleanup is temporary.
2. Contain the area. Plastic sheeting and zipper doors close off the work area, and air filtration keeps the air inside it flowing out through filters, so disturbed spores do not travel into clean rooms.
3. Protect the workers and the house. Crews wear protective equipment, and walkways to the containment are covered.
4. Remove growth and ruined materials. Moldy drywall, insulation and carpet are cut out, bagged inside the containment and carried out sealed.
5. Clean what stays. Framing and other solid surfaces are cleaned, often with sanding or wire brushing where growth went into the wood, then HEPA-vacuumed and wiped.
6. Dry and check. The area is dried, inspected for visible growth and dust, and only then closed up and rebuilt.

Mold rules in Texas

Texas regulates mold work through the Texas Department of Licensing and Regulation. Its rules separate two jobs: a licensed mold assessment consultant inspects the property and writes the remediation protocol, and a licensed mold remediation contractor carries the work out to that protocol. TDLR's FAQ is direct that a license holder is not allowed to do both mold assessment and mold remediation on the same project. Projects where mold affects 25 contiguous square feet or more require a notification to TDLR before work begins, and after a successful project a licensed remediator can issue a Certificate of Mold Damage Remediation, which a homeowner can show an insurer.

For a homeowner, that means a Texas mold job usually involves two different companies, and you should be wary of anyone who offers to inspect, test and then fix the same project. Our guide to Texas mold assessment and remediation explains each step, when the licensing rules apply, and how to look up a license on TDLR's site.

Mold rules in California

California has no state license or certification specifically for mold or moisture work, as the California Department of Public Health notes in its mold booklet. What does apply is contractor licensing: any job of $1,000 or more in labor and materials, or one that needs a permit, must be done by a contractor licensed by the Contractors State License Board. Since remediation usually includes removing and replacing drywall, insulation or flooring, that covers most real mold jobs. Look up any contractor on CSLB's Check A License page before you sign.

Testing: when it helps and when it does not

If you can see mold, testing usually is not needed to decide what to do: the EPA's position is that visible growth should be removed and the moisture fixed, whatever the species. Testing earns its place in other situations, such as a musty smell with no visible source, checking that a remediated area is clean before walls are closed, or when a Texas protocol requires it. In Texas, testing as part of an assessment is the assessment consultant's job, not the remediation contractor's.

Where mold turns up in Bay Area and North Texas homes

In the Bay Area, mold calls often trace back to crawl spaces with poor ventilation, bathroom ceilings with weak exhaust fans, and the cold north walls of older homes where condensation forms behind furniture. In Dallas–Fort Worth, attic and wall cavities after a roof leak or a freeze-split pipe, and air handler closets where condensate lines back up, are common sources. Both regions see mold after any water damage job that was not dried properly, which is why water damage restoration and mold work are so often the same job seen at two different times.

Sources: U.S. EPA, A Brief Guide to Mold, Moisture and Your Home; IICRC, S520 Standard for Professional Mold Remediation; Texas Department of Licensing and Regulation, Mold Assessors and Remediators FAQ and Mold Remediation Notification Requirements; California Department of Public Health, Information on Mold and Moisture for Renters in California (2020); CSLB, AB 2622 bulletin.