Skip to Main Content
Dangerous Mold in the Home

Types of Dangerous Mold in the Home

Mold can grow unseen in a home’s crawl space, walls, and basement, causing health problems for homeowners. It’s important to stop mold growth before it starts.

Schedule Free Inspection

Preventing Toxic Mold Growth Indoors During the Summer Months

Across the U.S., mold growing inside can cause health problems for homeowners, from allergies to asthma. In the past 12 months, residents of the District of Columbia, Kansas, Tennessee, Connecticut, New Hampshire, West Virginia, New York, Kentucky, Illinois, and Missouri logged the highest number of online searches for “mold removal,” according to Google Trends research.

Mold can grow unseen throughout your home in the walls, crawl space, and basement. It can affect the structural integrity of a home and ruin building materials, rugs and furnishings. On a hot summer day, humidity coupled with a lack of air circulation can trigger the growth and spread of toxic mold. In cities like Baltimore, Richmond, and Virginia Beach, warm summer months seem to start earlier and end later each year. With rising temperatures across the area comes an increased need to stop mold growth before it starts.

Dangerous Mold in the Home

Share this Image on Your Site!
Simply copy and paste the code below and you can share this infographic on your site:

» Download printable PDF

Common Types and What They Look Like

Mold is common and can be found growing almost everywhere indoors and outdoors throughout the U.S. Mold growing outdoors is natural and plays an important role in a healthy ecosystem. Mold found growing indoors, however, can be a huge problem – to your own health and the structural integrity of your home.

The most common types of mold found growing indoors in the U.S. are listed below. Each of these types of mold can negatively affect the air quality found in your home.

  • Cladosporium grows on moist acrylic-painted walls, wood, carpets, wallpaper, or other damp organic matter. There are 40 different kinds of Cladosporium and they come in many different colors including green, brown, gray, and black.
  • Penicillium is a different type of mold you may have learned about in science class or found in your own refrigerator on spoiled food. It causes food and other perishable items to spoil. Penicillium can also be found growing on walls, wallpaper, floors, and carpet. It can be blue, yellow, green, or white.
  • Alternaria mold often grows on iron, tiles, bricks, plaster, wallpaper, paper, and canvas. There are 50 different types of Alternaria mold, which is a common cause of allergies. Alternaria grows in dark gray spots.

Beware of This Toxic Mold

The most toxic type of mold found growing indoors is Stachybotrys chartarum. Often called “black mold,” it is a dangerous, toxic mold. Luckily, this type of mold growth indoors is rare. It is most often caused by long-term moisture in a home. For example, a home that has been empty for months without good air circulation or that has a leaky pipe could have toxic black mold.

It is very difficult to identify the difference between black mold and many of the other common types of mold that grow indoors. Toxic black mold is green-ish black in color and can produce a musty or rotten smell, what we think of as a “musty-smelling basement.” It can be found on water-damaged materials that have been damp for longer than 24 hours.

Because it’s difficult to tell the difference between black mold and other types, the Center for Disease Control recommends removing all mold immediately.

Preventing Mold Growth and Removing It From Your Home

Mold can harm your health even if you can’t see it. That’s why it’s important to stop its growth before it starts. The best way to stop mold from growing in your home is to reduce moisture inside the home. 

Remove Excess Moisture

One of the quickest and easiest ways to reduce moisture in the air is to run an air conditioner during the summer months and add a dehumidifier to rooms where moisture lurks, including the basement, crawl space, or other areas without good air circulation.

If moisture develops inside the home from a leak, open window, or other reason, it’s important to dry any wet areas, including carpets, walls, and furnishings – immediately. To reduce the chance of water leaking into your home, clean gutters and direct the flow of water away from exterior walls before the spring or summer rainy season. Get your home, including its foundation, inspected regularly for cracks, which can allow water into the home. If you use sprinklers to water plants and lawns, make sure they are not striking exterior walls directly or causing pooling water near the home, which could leak indoors.

Other Indoor Tips

There are many other ways you can help reduce mold growth indoors. Remove carpet from bathrooms and unfinished basements. Run fans to create air circulation in all rooms of the house, especially ones that are underused like basements, guest rooms, or storage areas. Don’t overwater indoor plants and clean air vents. Replace air filters regularly to reduce the spread of mold through the air. Cover pipes with insulation to reduce water pooling outside the pipes in the summer months. Clean all bathrooms regularly and remove all standing water, including inside showers and bathtubs. Keeping a clean kitchen, including removing perishable items from your refrigerator and cabinets, is also a good way to reduce mold growth.

Mold Removal

Finally, if you do find mold growing inside, remove it immediately. Throw away molding food, use cleaning products to completely remove mold from walls, and remove and throw away carpets, furnishings, and other items. Don’t just paint or caulk over mold in the shower, bathroom, basement, or other areas. Remove it completely using soapy water or a commercial mildew and mold remover. Once the mold is removed, identify the cause for its growth and fix the issue, or the mold will just grow back again! 

At JES, our professional basement waterproofing, foundation repair, and crawl space repair teams can help fix current problems and reduce mold growth in the future. To learn more about our industry-leading crawl space encapsulation system called CrawlSeal and how it can improve moisture control in your home, contact us today! 

Publish Date:

Last Modified Date:

Service Areas


8361 Town Center Ct
Nottingham, MD 21236


311 Central Rd.
Suite 2-02
Fredericksburg, VA 22401

Hampton Roads & NE NC

2569 Quality Ct
Virginia Beach, VA 23454

Northern VA & DC

7940 Gainsford Ct.
Bristow, VA 20136


309 Quarles Rd
Ashland, VA 23005

Southwest Virginia / Roanoke

2033 Cook Dr.
Salem, VA 24153

Western Virginia

456 Old Courthouse Rd
Appomattox, VA 24522


45 W Boscawen St,
Winchester, VA 22601