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How to prevent mold after a flood: 7 key steps

Updated Nov 11 2024

A woman wearing yellow gloves wiping down a shelf

Any amount of water left unattended can cause mold in the house, and mold can cause a lot of health-related problems, like allergies, asthma, and lung irritation. Mold can spread once water starts evaporating into the air, especially in humid or rainy conditions. That’s why it’s so important to immediately dry and clean water-damaged areas.

After a flood, you should work with either a water mitigation or water damage company recommended by your insurer recommends or a reputable one with a lot of positive reviews. These companies have experience and can help you dry out your home and prevent mold from spreading. 

That said, there’s work you can do to mitigate damage and prevent mold on your own, too. These tips can help.

1. Call your insurance company

Insurance companies require you to report your flood loss, even if flood isn’t a covered peril in your homeowners policy.* But beyond that, most insurance companies, Kin included, have water mitigation vendors they can recommend to help you when you have a water loss. 

When you report your claim, let your insurer know that you need some help with water mitigation, and its representative should be able to recommend vendors or send one out to assist you.

2. Get safety equipment

 Before you embark on cleaning and drying everything, make sure that you have the right safety equipment to do so. Here are some safety suggestions when dealing with flood damage:

  • Wear an N-95 safety mask to keep toxic particles at bay. 

  • Put goggles on to protect your eyes from dirty water.

  • Wear gloves and rubber boots to protect your skin.

  • Make sure that you only enter the area when you know it’s safe.

You know who usually has this kind of safety equipment? Professional cleaners. That alone may make it worthwhile to hire a water damage restoration company your insurer recommends. But if you need to mitigate your damages, be sure to do so safely!

3. Clean and dry the flooded areas right away

Time is of the essence when it comes to water damage. The longer water sits, the harder it is to make repairs. So plan to start drying and cleaning damaged areas within 48 hours of the flooding (if you can safely do so).

As soon as the storm stops, go through the house and check every room for water intrusions, spills, and leaks. Once you’ve identified the water damaged or flooded areas, start cleaning and drying them up. Remove water with a wet/dry vacuum cleaner. If you don’t have one, you can rent one or use old towels.

This is another reason hiring a reputable water mitigation or mold removal service company is a good idea. These kinds of companies have the right equipment and experience to get the job done correctly – particularly when the area is big (i.e., a garage or basement).

If you have wet floor carpets or rugs, dry them first using the wet/dry vacuum cleaner, and then use a fan to complete the drying process. Keep the fan on for 24 hours or more. You can also steam-clean your carpet once it’s dry.

4. Dehumidify the house & watch the humidity levels

Right after a storm or flood, moisture in the air can lead to mold growth. Getting the house as dry as possible is key to keeping mold at bay:

  • Open all the windows in your home.

  • Turn on all fans.

  • Use a dehumidifying machine to keep the air dry, clean, and cool.

You can also use a humidity monitor to keep an eye on humidity levels. Keep the relative humidity in your home lower than 60% –  ideally between 30% and 40% – to discourage mold as well as some pests. 

5. Check your home’s exterior

Check the outside of your home, too. Water pooling near the foundation can cause cracks and other damage, including mold growth. To prevent pooling water, you might need to fix the grading around the foundation, extend your downspouts, or add a French drain.

6. Sanitize everything

All water damaged areas, furniture, and things should be completely sanitized after cleaning. For your sofa, beds, and other furniture, use a steam cleaner or a wet/dry vacuum cleaner. For surfaces like floors and walls, use soap and water to clean and sanitize them using a water-chlorine bleach solution.

7. Throw away what can’t be cleaned (after your claim is approved)

Some materials can’t be thoroughly cleaned and dried. Others, like electronics, might be beyond repair if they’re waterlogged. Before throwing away your belongings, make sure the items and the damages they suffered are accounted for in your insurance claim. 

Your claims professional will need documentation of all damage to your belongings to approve your claim. You want to keep all damaged items until the claim adjuster can inspect them. If you can’t, make sure that you have taken a lot of photos or videos of all of the damaged items. These support your claim of damages, and your insurance carrier might not be able to extend coverage without them.

Keep paying attention to your home and surroundings even after you’ve done all these steps, especially throughout flood season and hurricane season. If you smell something musty, err on the side of caution and start cleaning.

Frequently asked questions for preventing mold after a flood

How soon does mold grow after a flood?

Mold and mildew can start to form within 24 to 48 hours of exposure to water. Worse? It continues to grow until you take the necessary steps to remediate it. 

What kills mold after a flood?

According to the Center for Disease Control (CDC), you can kill mold using bleach. However, the CDC emphasizes that you should only use one cup of bleach per gallon of water. Remember to also wear goggles, gloves, and an N-95 mask when working with bleach. 

How long should I run a dehumidifier after a flood?

You may need to run a dehumidifier anywhere from two days to several weeks. The amount of time required depends on how bad your flooding was, how big of an area was flooded, and what materials were soaked. 

When should I hire a professional mold remediation company?

In truth, a professional mold remediation company, especially one recommended by your insurance company, is usually a good idea. It’s safer than tackling the project yourself, and a professional team is likely to be more successful. That said, the Environmental Protection Agency says homeowners may be able to handle mold clean up if the affected area is less than 10 square feet.

One more important question is whether home insurance covers mold damage. The answer is sometimes. Get more details in our article Does home insurance cover mold?

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