How to Find & Fix Hidden Black Mold in Your Home

by | Sep 11, 2019 | Mold | 2 comments

Not sure if you have mold in your home? In some cases, you may be able to visibly see mold growing on surfaces or in corners of your living spaces. But sometimes it’s hidden, and you wouldn’t know it’s there unless you start to notice non-visible signs of mold such as spotty clothing, flare-ups of allergies or asthma, or an unpleasant, musty odor.


Mold is a common household problem, particularly in homes that have sustained water damage or leaks. If you see signs of mold in your home, a mold test can be performed on a sample to determine if it is indeed mold, and even identify the spore type!


how to find hidden black mold and fix it

What is Black Mold?

Molds have varied appearances and can be found in a variety of different colors. Contrary to popular belief, the term “black mold” – or sometimes “toxic mold” – does not technically refer to a particular type or species of mold. In fact, Stachybotrys chartarum is the scientific name for what most people refer to as black mold. It got this nickname because the colonies and spores appear black (or sometimes dark green) in color. However, not all “black molds” are Stachybotrys; there are several other molds whose colonies appear black, including Ulocladium and Chaetomium.


Stachybotrys chartarum got its official name approximately 200 years ago, derived from the Latin “charta,” meaning papyrus or paper. It’s commonly present in buildings with recurring leaks, since it requires a very wet environment such as a building that has sustained water damage. This type of mold is often found on cellulose ceiling tile, paper-backed insulation material, sheetrock, wallpaper, and even fibrous carpet padding in homes or buildings where water damage has occured.


Highly toxic compounds can be found in some species of Stachybotrys, but not all. Stachybotrys chartarum is a dangerous species of mold because it’s capable of producing a variety of secondary fungal metabolites that have been known to cause illness in humans. Molds that produce mycotoxins are often referred to as “toxigenic fungi,” of which there are many species, including certain species of Fusarium or Aspergillus.


Like many molds, Stachybotrys chartarum is an allergen, which can cause a variety of immune responses in humans that can persist until the mold is removed. Exposure to Stachybotrys chartarum is certainly a health concern. However, it’s worth noting that any mold growing in abundance in an occupied space can present a health risk and should be addressed immediately.

Looking for Signs of Mold in Your Home

Mold can occur in any damp location where it has the opportunity to feed upon organic materials. When looking for mold in your home, it’s important to keep an eye – and a nose – out for possible signs. Oftentimes, mold growth is hidden behind household furniture or appliances, making it more likely you’ll smell the mold before you see it.


In most cases, molds carry an earthy, damp, or musty smell. Stachybotrys mold can have a particularly strong smell, which is why it’s often more noticeable when it first starts to form. However, it’s important to remember that not all black-colored or strong-smelling colonies are Stachybotrys, and analysis should be conducted in order to confirm spore type.


RELATED: Everything You Need to Know About Household Mold

Common Places for Mold to Grow

mold in cold temperatures

If your home has sustained any type of water damage, it’s important to be on the lookout for possible signs of mold growth. Mold is commonly present in basement walls or floors after flooding or severe water damage has occured. Chronic or persistent leaking from appliances, sinks, and showers can also lead to mold growth. It doesn’t take a lot for mold to survive and thrive. In fact, most types of mold only need water, organic matter, a dark environment, and time to grow. That’s why it’s often found in places that aren’t heavily trafficked in the home.


When looking for hidden mold, start by searching for any evidence of water intrusion. Although it can be difficult to detect mold growing in the walls, it’s important to look in these areas in order to identify the problem as quickly as possible. Moisture meters and particle counters may be used by a certified inspector to find the source of a water leak and fungal growth, and they can even help detect if there is mold in your walls.


Some of the most common areas for mold to grow in the home include:

  • Basements
  • Crawlspaces
  • Behind furniture or appliances
  • Inside wall cavities
  • Ceilings
  • Window sills
  • Insulation material
  • Air ducts
  • Near plumbing


Keep in mind that mold is a sign of excessive moisture and water intrusion, and it may be visible or hidden behind a variety of different surfaces. Whether it’s caused by a leaking pipe or previous water damage, mold can lead to costly building repairs and even adverse health effects, which is why it should be handled promptly when found.

Testing for Mold in the House & How to Get Rid Of It

If you suspect there is mold growth in your house, it’s important to determine the severity of the problem with a mold inspection. In serious cases where household mold is left untreated, it can cause allergic reactions and illness and create a need for expensive home repairs.


During a mold inspection, a trained professional will come to your home and use a specialized high-flow air pump attached to a cassette in order to collect any spores that may be present. They may also use special tubes that enable them to take samples inside wall cavities, where molds frequently grow. Inspectors will also take an outdoor sample in order to compare the indoor results to the natural outdoor air. Once the sampling process is completed, the obtained samples will be sent to the laboratory where an analyst will remove the spore trap from the cassette and mount it on a microscope slide for analysis. The laboratory analyst will then identify and quantify any mold spores that may be present and generate a detailed lab report.


If the results of the analysis indicate that more mold is present inside of the home than outside, you may choose to have mold remediation performed to address the issue. A mold-remediation or water-damage specialist may remove the affected materials (drywall, carpet, and even furniture) and use a special fan to dry the area completely. Many people choose to have an additional mold survey performed after remediation to ensure that no sources of mold were missed and that the removal process was successful.


Keep in mind that mold remediation only removes the symptom. In order to truly have peace of mind about the health of your family and your home, it’s important to also locate the source of the moisture that led to the mold growth in the first place and make any necessary repairs as you clean up the mold. When testing for mold in the house, professional services are available to help you find hidden mold and moisture problems in your home.

How to Prevent Mold Growth

Woman Looking at Black Mold on Ceiling and Walls of Home

Water damage is the most common cause of serious mold problems in the home. After flooding, leaking, or another type of moisture damage occurs, mold can begin to grow within the first 48 hours. There are some things you can do to prevent mold after water damage, including drying the area as quickly as possible by removing water and using fans and/or dehumidifiers.


If you live or work in a particularly wet environment, you may want to use a dehumidifier to minimize moisture on a regular basis. Maintaining a low relative humidity (<60%) can do wonders in preventing mold from establishing itself indoors. 


Other tactics for preventing mold growth include ensuring proper ventilation in enclosed areas such as bathrooms and laundry rooms and fixing any leaking roofs, walls, or plumbing as quickly as possible.


RELATED: How to Prevent Mold Growth in Winter and 5 Best Ways to Prevent Mold Growth in Commercial Buildings

If You Suspect You Have Mold Growth, JSE Labs Can Help!


Mold can be a tricky problem to deal with in your home. If you think you might have a mold problem, the first thing you should do is have a certified inspector assess the damage or bring a suspected mold sample to a laboratory for testing. At JSE, we specialize in mold identification and can provide you with an accurate analysis of your sample.


Our mold lab offers quick turn-around times and our consultants can answer any questions you may have. In-house laboratory services include mold spore analysis by direct exam for both bulk and air samples. 

Mold can be a pesky problem in any household. If you suspect you have mold growth in your home, contact JSE online or at (503) 659-8338 to get your sample tested.

Lisa Jones-Stohosky

Lisa Jones-Stohosky

Lisa started in the industrial hygiene and environmental industry in 1992 as an asbestos microscopist and began performing building inspections for asbestos, lead paint, and other hazards in 1994.

“This career has been an amazing experience, traveling for work to perform inspections both locally and abroad to locations such as Hawaii and Germany. My real love however is being in the laboratory and assisting our wonderful clients.”

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