Black Mold: A Homeowner's Guide to Detection and Remediation

By: Licensed Mold Assessor Brad Fishbein

January 30, 2023

As a professional mold inspector, people often call me in a panic. "I have Black Mold!"

But here's what you should know.

Not all mold that is black in appearance will produce mycotoxins, but it's essential to confirm that mold is not toxic and harmful to your family.

Concerned about Black Mold?

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What Is Black Mold?

Black mold is a specific species of fungus called Stachybotrys. Stachybotrys is a slow-growing mold that needs extensive amounts of water on porous building materials to grow and thrive. It may produce off-gassing of mycotoxins, which can be harmful and toxic for humans and their pets. Stachybotrys may also be green and gray in appearance as well as black.


Black mold is a slang term that was created by the media. There is no scientific definition for Black Mold.

Here's the thing:

If the media makes up a term we, as a society, tend to run with it.

When you hear that term, it is referring to one particular species of mold. Keep in mind there are over 365,000 known species.

Throughout this article, you will see the term black mold, toxic mold, and black toxic mold, which will all refer to Stachybotrys.

While Stachybotrys is considered the king of toxic mold, other types of mold may be toxic as well.

What Does Black Mold Look Like?

The black toxic mold would be very slimy on the surface with the appearance if it colored in darkly with a black, gray, or green crayon when wet. Once dried, Stachybotrys can start to resemble black chalk with a dusty appearance.


Is Black Mold The Only Dangerous Mold?

Stachybotrys is not the only dangerous species of mold that can be toxic. Other dangerous species include Chaetomium, Memnoniella, Fusarium, Penicillium, and Aspergillus.

So how did this one particular species get so much notoriety?

The mold itself is not toxic. Stachybotrys can produce something called Mycotoxins. Mycotoxin is a fancy word for toxic. While Stachybotrys is not the only type of mold that can be toxic, it is the most feared of the toxic mold types you would find growing indoors.


That alone did not make black toxic mold famous. The media did its job and reported on a couple of high profile cases, some of which involved celebrities which will always get more attention. Two instances were the Ed McMahon Case and The Cleveland Drop Case.

But just like anything with the media, it got taken to the next level.

Is all Mold That Looks Black Toxic?

Not all mold that is black is toxic. Mold can come in all shapes and colors. Just because mold is black in appearance does not mean it 'ss absolutely Stachybotrys nor is it guaranteed to be toxic.


All these black mold spores have one thing in common:

You don't want it anywhere in your home!

For example:

In my 10+ years in the mold industry, I have seen mold in shades of black, gray, green, brown, white, and even red!

I have seen them form some weird patterns as well.

Look at the picture below and tell me if you saw this in your home what you would think:


You probably think that the black part is the "Black Toxic Mold "correct?

You would be wrong…

None of that mold is Stachybotrys at all. The types of mold that were found here were called Penicillium and Aspergillus. These are two separate mold species that are very hard to differentiate under a microscope.

Here's the thing though:

As I told you earlier, there are individual strands of these types of spores that may produce mycotoxins such as one called Ochratoxin. Either way, you would want the mold damaged wall and entertainment center removed.

If you look at this picture further, you will see that black is not the only color present. There is also brown, gray, and green.

This is what you need to know:

Just because mold is black, does not guarantee that it is toxic and just because mold is not black doesn't ensure it's not toxic!

What Does Black Mold Smell Like?

Black mold has a distinctively pungent odor that can resemble similar to rotting for or decaying garbage. The odor will increase with relative humidity in a building higher than 65%. To remove the smell, a process called mold remediation may be necessary.

Is it as cut and dry as removing black mold will remove the odor of it?

Not quite.

Even after removal, if all the remaining non-sanitized building materials and non-treated air remain, the smell may linger.

That is why proper protocols need to be put in place and followed.

Before you learn how to remove black mold, you must learn what caused it to get in your home in the first place.

How Does Black Mold Grow?

Black toxic mold will grow when a water leak affects porous build materials that are not dried out for an extended period time. Often when a leak is not known or neglected for weeks or months, black mold will thrive under the right building conditions.

So what are the right building conditions?

The correct building conditions are wet and humid places with lots of porous building materials present.

The three ingredients that will allow Stachybotrys to flourish is:

  • Water
  • Relative Humidity 60% or above
  • A nutrient (drywall, wood, etc.)


Is Black Mold In The Shower Dangerous?

Showers are typically built to withstand water. While the mold found on the shower tiles may be black, it is unlikely the type of moldis Stachybotrys. Showers built with cellulose-based building materials, it is possible black mold can be present behind the shower tiles or fiberglass.


How Long Does It Take Black Mold To Grow?

The exact time it takes for black mold can vary. On average, under the right conditions, Stachybotrys has been known to grow in as little as thirteen days. If caused by a slow leak, black mold will more likely start to grow within 4-6 weeks if not dried.

Time is of the essence when dealing with leaks.

Stachybotrys can't grow without water and lots of it!

Bottom Line:

If an area is leaking or flooded, it needs to be dried out immediately.

Can Black Mold Be Airborne?

Stachybotrys is an extremely heavy spore that may not always be airborne when it is wet and heavy. When black mold is dried out, and dead, there is a better chance it can become airborne and affect the air quality within a building.

Mold damaged building material which is disturbed increases the chances to become airborne.

Fragments of mold spores may also be found in dust particles that will not always show up on traditional air samples. This air can be circulating your home and contaminating your air conditioning system.

Can Black Mold Spread From A Neighbor's House?

Black mold from one's home can affect the neighbor's house if there is shared wall cavity space such as in apartments or townhomes. Typically mold will not spread from one detached structure to another such as a single-family home.

Does this mean just because your neighbor had a leak that there is a mold problem in your wall?


It all depends on the construction of the building and the significance of the leak in their home.

In most cases, if a unit above leaks, it will most likely affect the unit below for a straightforward reason:

Water flows downhill.

How Is Black Mold Identified?

Collected mold samples on a medium such as a bulk sample, swab sample, or even air sample are sent to a laboratory. A microbiologist then identifies the spore type which can be Stachybotrys or other mold spore species under a microscope.

But who collects the samples?

Well, you can hire a licensed mold inspector who may tell you many issues about your house that you did not know.


I always recommend the mold inspector route if possible, to avoid any contact with dangerous toxins produced by mold growth. However, getting a mold inspection can be expensive.

Can Black Mold Be Cleaned?

Because black mold can be toxic, it should always be removed and never cleaned. Personal Protective Equipment (PPE)will need to be used when removing. Furthermore, if Stachybotrys has been confirmed present, a proper containment barrier should be installed to prevent cross-contamination of airborne mold spores.

Is this something you should try for yourself?


The EPA disagrees.

Well, sort of…

Here they say:

"Who should do the cleanup depends on several factors. One consideration is the size of the mold problem. If the moldy area is less than about 10 square feet (less than roughly a 3 ft. by 3 ft. patch), in most cases, you can handle the job yourself." Source

Which is excellent and for the most part correct, but in my professional opinion too black and white and doesn't cover the grey areas.

They do say "one consideration" so they are indicating it's not the absolute rule.

Black mold because it can be harmful to one's health should always be handled by a trained professional.

How To Properly Remove Black Mold

Removal of excessive mold growth (especially black mold) should be done through a process mentioned above-called mold remediation. Mold remediation involves the process or removal on mold-contaminated building materials and sanitization of structural materials that will remain. The purpose of mold remediation is to return the water damaged area back to it's original condition with cross-contaminating otherwise clean areas.

Mold remediation may be done by a specialist who's business concentrates only on mold abatement or possibly a licensed contractor.

There are proper procedures that should be followed to ensure things are not made worse.

The two resources most in the mold remediation industry refer to for the proper way to perform mold remediation is:

  • New York City Department of Health Guidelines on Assessment and Remediation of Fungi in Indoor Environments,
  • The Institute of Inspection, Cleaning and Restoration Certificate (IICRC) S520

You should not have a regular handyman attempt to remove an area of extensive mold damage!

How Much Does It Cost To Remove Black Mold?

The cost of mold remediation can be determined by how much of an area needs to be removed and properly cleaned. A typical fee is approximately $3500 per average size 10x12 room. Prices can vary from vendor to vendor.

Correctly performed mold removal is not cheap!

When hearing about the cost of how much it costs to remove mold, you will be tempted to do the work yourself.

Just keep in mind….

You can't put a price on your health!

So if you don't know what you are doing, you should think twice.

Who Pays For Mold Remediation?

Mold remediation may be covered by homeowner's insurance policies under the "fungi" section. The typical amount covered by homeowner's insurance is $10,000 per occurrence. In certain cases, when an uncovered loss on the policy caused mold growth, this will be excluded.

Knowing your homeowner's insurance policy is always a good idea when determining if you are covered or not.

If homeowner's insurance does not cover you, there is a good chance you will be responsible financially.

Is A Home Safe After Black Mold Removal?

If proper procedures are done during the mold remediation process, the building space will be safe to move back into in regards to toxins produced by mold. This includes the removal of not only mold-contaminated building materials but construction dust and airborne mold spores.

Every jurisdiction has different regulations (if any) when ensuring mold removal was done correctly.

A common occurrence after the work is completed for a third party mold inspector be called in to perform a clearance test.

A clearance test can involve a visual inspection as well as sampling to ensure the removal of all contaminated building materials. Any remaining building materials are correctly sanitized.

How Does Black Mold Affect Your Health

The black mold itself is not what causes health concerns; it's the mycotoxins it produces. Mycotoxins can lead to many adverse health effects such as upper respiratory conditions, headaches, and a variety of other symptoms. Persons with compromised immune systems are especially at risk.

Some other health effects that mycotoxins from Stachybotrys may cause are:

  • Coughing
  • Itching
  • Dizziness
  • Upset Stomach
  • Breathing Problems

There are also less common symptoms reported. Black mold can affect people in different ways.

Here's The Deal:

We aren't going to acknowledge every studied associated with the health effects of toxic mold, but there is one study that I will point out.

It was a study in 2014 that linked Autism with women exposed to high levels of air pollution during pregnancy, which can include toxic mold.

The study showed the risk of Autism doubled in children with a mother exposed to high levels of air pollution during the third trimester of pregnancy.

I did look over the study, and there are some limitations. But overall, it holds an argument and is worth checking out. You can check it out by clicking here.

Is Black Mold Dangerous For Pets?

Black mold can be just as dangerous for pets as it is humans. In some cases, pets such as cats and dogs may be even more susceptible to getting sick from black mold due to their overall time spent in the home in some cases being more significant than their owners.

Pets are part of the family but let's face it; they may not be as easy to diagnose when they are sick.

Most of the time, pets have to be not acting like themselves for you to notice there is something wrong with them.

How To Diagnose Black Mold Sickness

Sickness caused by toxins produced from the black mold is diagnosed through blood tests. Urine testing for black mold sickness are not reliable and should be avoided.

Unfortunately, here in the United States, there are very loose restrictions for mycotoxins allowed in food. Mycotoxins can cause urine to be affected where it cannot be determined if it's from the food one ate or water-damaged buildings.

Can Black Mold Exposure Be Treated?

Yes, there are two easy steps to treatment for black mold exposure:

  1. Remove the affected person(s) from the contaminated areas
  2. Get treated with anti-fungal medication by your doctor or their recommended form of treatment.

Typically, a healthy person will feel better instantly when leaving the affected areas.

I have known people to feel okay at their work but start having building-related symptoms in their home due to water-damaged building materials.


There have been cases reported of people's immune systems are never fully recovering and being overall weaker due to black mold exposure for a long time.

Another option is taking supplements that are known as toxin binders. A standard toxin binder is called activated charcoal, which may help flush toxins from the body.

What Other Questions Do You Have About Black Mold?

Congratulations, if you made it through this entire article, you now know what people refer to as "black mold" and how it affects you.

Keep in mind, even if you do not have black mold growing in your home, other types of mold can affect you.

Mold caused by water damage should be taken seriously.

If you have any questions about black mold, we'd love to hear from you!

Meet the author: Brad Fishbein is an ACAC council-certified Microbial Investigator. In the fall of 2012, he became a Licensed Mold Assessor in the State of Florida through the Department of Business & Professional Regulation. Brad has helped homeowners with over 5,000 successfully completed Mold Inspections since 2009.

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