Open Accessibility Menu

What are the Differences Between Mold and Mildew?

Two types of fungi that are common in homes are mold and mildew, and they have a lot in common. Both substances flourish in moist settings, effortlessly spread to new areas, are difficult to remove from surfaces they settle on, and can cause issues for people’s health and your home’s structure. Despite the commonalities between the two, it is important to know how to distinguish mold and mildew. This is because they each have their own unique risks and need to be addressed differently when it comes to cleaning.

Refer to the following guide to learn the difference between mold and mildew so that you can properly treat cases of either fungus.

Identifying Mold and Mildew: Appearances, Effects, and Types

Mold and mildew are both types of fungi that can thrive indoors and affect your health or cause structural damage to your property.


Mold is a fungus that has numerous identical nuclei, appears in green or black patches, has a slimy or fuzzy texture, and affects materials beyond their surfaces. Mold will penetrate any surfaces it has affected. This not only makes it difficult to treat cases of mold, but this can also lead to structural damage in addition to health concerns. Among the common health effects caused by mold are allergic reactions and respiratory issues, but they vary depending on the species.

While there are over 10,000 different mold species that can be found indoors, there are five types of mold that are most often found in households.

  • Alternaria: This mold is found in damp places like near windows, in showers, on walls, or beneath sinks. Alternaria is usually found in water-damaged places. It has a wooly texture and can be dark brown, gray, or black. Additionally, extended exposure to this mold can result in asthma attacks and allergic reactions.
  • Aspergillus: This mold is the most common one found indoors, usually growing on clothing, walls, paper products, and insulation. Color-wise, it can either be black, brown, green, white, or yellow. Among the health concerns it causes are respiratory infections, allergic reactions, and lung inflammation for people with weak immune systems.
  • Cladosporium: This mold is dissimilar to a great deal of molds in that it grows in cooler environments. It develops on wood surfaces, such as hardwood flooring and cabinetry, and on fabrics, such as curtains and carpeting. Cladosporium can be olive green or black in color and can result in various respiratory problems.
  • Penicillium: This mold grows on materials that have come into contact with water. Among the materials it can affect are carpeting, insulation, mattresses, and wallpaper. Penicillium gives off a strong musty smell and appears green or blue. Its spores are known to spread easily and cause allergic reactions.
  • Stachybotrys chartarum: This mold is the most harmful of all household mold species. It is more commonly known as “black mold” because of its black appearance. Black mold has a musty odor and grows in constantly damp environments, such as within air conditioning ducts, near leaking pipes, and anywhere else where there’s an abundance of condensation. Furthermore, black mold has mycotoxins, toxic compounds that result in serious health concerns: asthma attacks, allergic reactions, breathing issues, chronic sinus infections, depression, and fatigue.


Mildew is a fungus that appears in white, yellow, or gray patches. With time, mildew often changes color to brown or black. It also has a fluffy or powdery texture and grows on the surface of moist materials. As such, mildew is easier to clean, and its growth will not be concealed like mold growth can be. Health-wise, if a person were to inhale mildew, he/she could develop a headache, a cough, sore throat, and other respiratory problems.

Furthermore, mildew is a plant disease that extensively damages plants and crops and is categorized into two types:

  • Downy mildew: This mildew has a varying appearance depending on what surface it has developed on. For the most part, downy mildew begins as yellow spotting that will eventually darken to brown. It is found most often in agricultural products like potatoes and grapes.
  • Powdery mildew: This mildew begins as patterned splotches that are gray or white in color, eventually turning yellowish brown or black as the fungus further develops. Powdery mildew mostly concerns flowering plants.

Testing for Mold and Mildew

In the event you are unable to identify or unsure whether you have a case of mold or mildew in your home, there are tests you can perform that help you figure it out.

Home Testing

Get household bleach and place a few drops of the bleach on the affected material(s). Five minutes later, check the spot that you’ve bleached. If the fungus has lightened in color, then it is a case of mildew. If the fungus stays dark, then it is a case of mold.

If you don’t want to use bleach, you can instead purchase a mold and mildew testing kit.

Professional Testing

The best way to figure out whether you are dealing with mold or mildew in your home is to hire professionals, as they are trained to identify and address such fungi. Find and contact a local company that offers mold remediation services, and the professionals will do an inspection, testing, an evaluation, and treatment to remove the fungus.

Cleaning Mold and Mildew

Because of its ability to penetrate materials and reach their interiors, mold is difficult to clean. The mold attaches itself to materials it has affected. The spores easily spread to new areas and can withstand extreme conditions, making it even more difficult to treat mold. Furthermore, the longer mold goes untreated, the greater chance there is of it causing structural damage and health problems.

While there are do-it-yourself techniques one can perform to treat mold, they are often ineffective. Such remedies treat the fungus at the surface, but the mold often has penetrated the material’s surface. That said, the mold needs to be addressed beneath the surface, and getting professional help is your best bet for this. Professionals have the proper equipment and will use the correct techniques to ensure the removal of mold from your home.

Meanwhile, mildew is different in that it can be cleaned easily. As a surface fungus, mildew can be removed by using a scrubbing brush and commercial cleaner. You just need to make sure that, when you clean mildew, there’s proper ventilation in the area you’re working in and that you wear a face mask. This will prevent you from inhaling any mildew spores and fumes from cleaning products. Rubber gloves are also recommended to serve as protection from the fungus and cleaning product.

In addition, be sure to also clean the nearby areas to ensure the mildew has been thoroughly removed.


The best way to prevent your home from suffering from mold and/or mildew growth is to keep the place dry and free of moisture. The following are some tasks you can take to ensure that your home maintains an environment that doesn’t allow mold and/or mildew to thrive:

  • Keep the humidity level in your home around 40-50%.
  • Use a dehumidifier to maintain a proper humidity level in your home.
  • Repair leaks in your home’s kitchen, bathroom, and other areas.
  • Get regular inspections for your home’s heating and cooling systems.
  • Maintain your home’s air ducts.
  • Get rid of any plants that have been affected by mildew.

If you find fungus growth in your home, use the aforementioned information to help you determine whether the substance is mold or mildew and figure out how to address it. Although they share many similarities, mold and mildew are different fungi that need to be addressed differently. Mold and mildew each come with their own health concerns, which makes it even more important for you to treat the fungus immediately.

In the event that the fungus is mold, get in touch with ServiceMaster Kwik Restore for our mold removal services. Our professionals will evaluate the damage the mold has done to your home, contain it to prevent further growth, eliminate the mold from its source, clean the area, and stop the mold from reappearing on your property. Additionally, we are trained and equipped to remove mold and will restore your home to a safe living environment.