Mold After Flooding in Houston: What to Do First

Why does mold follow Houston floods so quickly?

Mold needs moisture, a surface to feed on and time. A flooded Houston house supplies all three at once. Drywall, carpet pad, wood trim and fiberglass insulation soak up water, the outdoor air is warm and humid most of the year, and the clay soils under many neighborhoods drain slowly, so the ground around a slab stays wet for days. EPA advises drying water-damaged areas and items within 24 to 48 hours, and it says that if a home was flooded and could not be dried in that window, you should assume mold is growing.

The scale of past storms shows why this matters here. After Hurricane Harvey in 2017, the Houston Health Department reported that many areas that had never flooded, and sat outside the identified floodplain, were inundated with several feet of water. In parts of Kingwood, such as Kingwood Greens Village, Barrington and Fosters Mill, more than 80 percent of homes took water damage, according to the district council member. An estimated 3,000 homes flooded in Friendswood along Clear Creek, and Bellaire counted more than 2,000 flooded structures. After a widespread flood, what you do yourself in the first two days carries extra weight.

What should you do in the first two days?

1. Get back in only when it is safe. Follow the local all-clear, and keep power off in wet areas until it has been checked.
2. Document before you remove anything. FEMA tells flood policyholders to take photos and video inside and out, write detailed descriptions of the damage, and keep samples of items such as flooring and curtains for the adjuster.
3. Start the claim. Call your flood insurance agent. A standard homeowners policy does not cover flood, so the flood policy is usually the one that matters.
4. Get water and wet materials out. Pull up carpet and pad, bag soaked items and start moving air. Porous materials such as carpet and ceiling tiles may have to be thrown away if they are moldy, per EPA.
5. Leave the AC off if the ducts or air handler took water. EPA says not to run an HVAC system you know or suspect is contaminated, because it can spread mold through the house.
6. Protect people. EPA recommends at least an N-95 respirator during cleanup, says children should not take part, and says people with asthma or weakened immune systems should stay away from moldy areas.

Which materials usually have to come out?

The answer depends on how long things stayed wet and what they are made of. A mold assessor will spell out exact cut lines and quantities in the written protocol, but the general pattern looks like this.

Do not paint or caulk over mold to hide it; EPA says the growth has to be removed and the surface dried. If you are not sure how far moisture went, a mold inspection in Houston with moisture readings will show which walls still hold water. Our guide to early signs of mold in a house covers what to watch for in rooms that seemed to dry out.

Can you clean up flood mold yourself in Texas?

Yes, in your own home. TDLR says homeowners may sample for mold or clean it up in their own home without a TDLR mold license. EPA suggests that most people can handle a patch under about 10 square feet, but a flooded house almost always has far more than that, much of it hidden inside walls.

The rules change when you hire help. Anyone you pay to assess or remediate mold must hold the right TDLR license unless an exemption applies. Owners and staff of residential buildings with 10 or more units, and of non-residential property, may handle mold below 25 contiguous square feet themselves; at 25 square feet or more, the work must be done by a TDLR mold remediation license holder. That threshold is an exemption for owners and their staff, not a cutoff for the whole law.

For a hired job, Texas sets the order of work:

• A mold assessment consultant writes a remediation protocol and gives it to you at least one calendar day before work starts.
• A separate remediation company writes a work plan that meets the protocol. Texas law bars the same company from both assessing and remediating the same project.
• The remediator notifies TDLR at least five days before a project of 25 contiguous square feet or more.
• After the work, the consultant does a post-remediation clearance check, and within 10 days you receive before-and-after photos and a Certificate of Mold Damage Remediation (CMDR).

Our guide on checking a Texas mold company walks through how to confirm both companies on TDLR's license search.

How does flood insurance treat mold?

Flood policies through the National Flood Insurance Program put the burden on the owner to act. FEMA states that it will not cover mold damage if a policyholder fails to act to prevent the growth and spread of mold. In a 2022 appeal decision, FEMA also pointed to the policy exclusion for mold and moisture that stems from conditions within the owner's control, including failure to inspect and maintain the property after a flood recedes. The practical lesson is to start drying and removal quickly and keep records of what you did and when.

FEMA also says the signed Proof of Loss must reach the insurer within 60 days after the date of loss unless that deadline is extended in writing. For how homeowners policies handle mold that is not flood related, see whether homeowners insurance covers mold in Texas.

Do you need a permit to rebuild after a flood?

Often, yes, and the office depends on where you live. Inside the City of Houston, including Kingwood, the Houston Permitting Center handles building permits, and most renovation and repair projects need plan approval first. In Bellaire, all flood-related repairs require a permit obtained before work begins, and buildings that are substantially damaged (50 percent of pre-damage market value) must meet current floodplain rules. In unincorporated Harris County, including much of Spring, the Office of the County Engineer requires a permit for all development, including floodplain work. Clearing mold is usually separate from the rebuild, but make sure clearance is passed before new drywall goes up.

What does flood mold removal cost in Greater Houston?

Angi's Houston cost data reports that mold removal averages $2,016, with a typical range of $863 to $3,329 and a full range of $500 to $5,500. Flood jobs tend to land at the upper end or beyond, because the affected area is large. HomeGuide's national ranges for 2026 put large areas of 300 to 1,000 square feet at $6,000 to $15,000 and whole-home jobs over 1,000 square feet at $15,000 to $30,000. Because Texas requires two different companies, budget for the assessment as well; Angi's Houston cost data puts mold inspection and testing at an average of $453. The Houston mold remediation cost guide breaks these numbers down further.

What if you rent?

After Harvey, the Houston Health Department recorded community concerns about landlords not finishing mold remediation in flooded units and residents living in flooded housing without it. Texas law requires landlords to make a diligent effort to repair conditions that materially affect health or safety once properly notified. The Health Department responds to indoor air quality issues in apartments, though it does not test for mold. Our guide for Houston renters dealing with mold covers notice and next steps in plain terms. Homeowners further south, from Dickinson to League City, can also find independent local companies through our Greater Houston service areas.