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The Home Depot

5 Causes of Household Mold

Pro Referral > Home Guides > Cleaning > 5 Causes of Household Mold
5 Causes of Household Mold

Residential mold carries significant health risks with it, which can cause illness for people exposed to the mold and mildew. If you detect mold in your home, it’s important to resolve the issues quickly and thoroughly to prevent health issues and damage to your home.


The Environmental Protection Agency has information about residential mold available on its website. You will find an overview of mold, as well as advice for cleaning mold and preventing it from returning. Because of the potential for serious ramifications from mold, it’s important to stay vigilant with frequent inspections of household surfaces.


Once you know five causes of household mold, you can maintain your house in a safe and clean manner.

  1. Home foundations are porous, meaning that they will absorb water from the outside and allow it to enter the interior of the home.

    Environment for Mold Growth

    Mold can develop on virtually any surface, but it does require a specific environment to grow and spread. Mold needs favorable temperatures, moisture and nutrients to develop. When the environmental temperature falls between 40 and 100 degrees Fahrenheit and when relative humidity levels are above 70 percent, the temperature and moisture level is ideal for mold growth to occur on any surface that will provide the necessary nutrients.

  2. 1.Flooding

    If you experience a flood in your home, your house is at risk for developing mold from the abundant moisture. With the interior environment at the proper temperature for mold development, mold can develop quickly.


    It’s very important to dry your interior areas as quickly as possible after a flood to prevent mold from developing. By running air conditioning, a furnace or dehumidifiers, you can help dry out the interior areas more quickly.


    Wet carpeting is often a total loss, so remove wet carpeting quickly instead of attempting to dry it. Leaving the carpeting in place provides an ideal environment for mold to develop.

  3. 2.Plumbing Leaks

    Plumbing leaks can often occur behind drywall or sheetrock or beneath flooring. Left unnoticed and unrepaired, the moisture may quickly develop into mold. By the time you detect a problem, the mold may have already caused unsightly damage to surfaces. If this occurs, you must remove and replace the damaged surfaces.

  4. 3.Foundation Moisture

    Home foundations are porous, meaning that they will absorb water from the outside and allow it to enter the interior of the home. If you notice crystallization on the interior surfaces of your foundation – called efflorescence – this may indicate a moisture issue with your foundation. Left untreated, mold may develop.

  6. 4.Indoor Humidity Level

    Many activities in the home can contribute to excessive humidity levels. Cooking, bathing and laundry are three of the main culprits than can push a home’s humidity level to the point where mold may develop. Use exhaust fans to remove excess moisture from the air in your home. Running an air conditioner or dehumidifier should also help control indoor humidity levels.

  7. 5.Attic Moisture

    Mold may develop in the attic due to several issues. If a roof leaks, moisture will enter the attic area. Another situation that can contribute to attic moisture involves leaks that allow air from the living areas to leak into the attic. During the winter, this warm air will condense when it hits the cold air in the attic, creating moisture. Over time, this moisture could cause mold to develop.


    With a watchful eye and fast remedial work, you can make sure your home stays free of mold problems.

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