Found Mold in Your House? What to Do First

The short answer: stop the water that is feeding the mold, dry out anything wet, and then decide who will clean it up. Testing usually is not needed. The EPA sums it up in one line: "The key to mold control is moisture control."¹ The CDC gives the same two-part instruction — clean up the mold and fix the moisture problem.²

Here is what to do, in order.

1. Find and stop the water

Mold needs moisture to grow, so the leak, drip, or damp spot comes first. The EPA's cleanup steps start with fixing "plumbing leaks and other water problems as soon as possible."³

This step is easy to skip when the mold itself is the thing you can see. But the EPA is direct about what happens if you do: clean the mold without fixing the water, and "most likely, the mold problem will come back."⁴

Common sources worth checking: a leaking pipe under a sink, a roof or window leak, a dripping air conditioner line, or condensation on cold surfaces.

2. Dry anything that got wet — fast

Both agencies use the same window. The EPA says to dry water-damaged areas and items "within 24-48 hours to prevent mold growth."⁵ After a flood, the CDC says to clean up and dry out your home "fully and quickly (within 24–48 hours)."⁶

3. Don't run a heating or cooling system you think is moldy

If the mold is in or near your HVAC system, leave it off until it has been dealt with. The EPA warns that running a contaminated system "could spread mold throughout the building."⁷

4. Work out how big the problem is

Size decides whether this is a job you can do yourself.

• EPA guidance: if the moldy area is less than about 10 square feet — roughly a 3-by-3-foot patch — the EPA says that "in most cases, you can handle the job yourself."⁸
• Texas licensing: Texas sets its own line for when a license is involved. The state licensing agency says visible mold "of less than 25 contiguous square feet can be cleaned up by people who are not licensed" in most instances.⁹

For how to clean a small area safely, see Can you remove mold yourself?

5. Skip the mold test in most cases

If you can see the mold, you usually do not need to test it. The EPA says that when mold growth is visible, "sampling is unnecessary" in most cases.¹⁰ You also do not need to find out what kind it is. The CDC: "You do not need to know the type of mold."¹¹

There are a few situations where testing can help. See Do you need a mold test?

When to call a professional right away

The EPA points to a professional in these situations:

• The water was sewage or otherwise contaminated. Call "a professional who has experience cleaning and fixing buildings damaged by contaminated water."¹²
• You think mold is hidden — behind drywall, under carpet, or somewhere you can smell but not see. The EPA says to "consider hiring an experienced professional."¹³
• You have health concerns. The EPA says to "consult a health professional before starting cleanup."¹⁴

Two things not to do

• Don't paint over it. The EPA is plain: "Do not paint or caulk moldy surfaces."¹⁵
• Don't mix cleaners. The CDC warns never to mix bleach with ammonia or other cleaners, because it "will produce a poisonous gas."¹⁶

If you hire a company in Texas

Texas licenses mold work, and two rules shape how a licensed job runs:

• Plan on two firms. The company that assesses the mold and writes the plan cannot be the company that removes it on the same project.¹⁷
• Expect a form before any work starts. Licensed assessors and remediators must give you the Consumer Mold Information Sheet "before any mold-related activity begins."¹⁸

You can browse licensed Texas mold companies, each listed with its state license number and the date we checked it. For how licensing works, see Do mold remediation companies need a license in Texas?