Black Mold: Everything You Need to Know When it Appears in Your Home

Kenneth Wilson

If you believe you have a black mold infestation appearing in your home, then you need to become knowledgeable on this post. Black mold doesn’t just ruin the visual appearance of your home, but it can actually cause some serious health problems to those living there. But, before we discuss that topic further, what is black mold? 

Black mold, otherwise known as a fungus-like stachybotrys chartarum, is one of the most harmful molds commonly found in homes. Typically, this bacterium will thrive in highly damp and warm areas like a laundry room, bathroom, or a recently flooded area.  

Now you understand what black mold is, let’s dive further into the topic. We know that black mold is incredibly harmful to humans. To understand this further, below, we discuss the symptoms, how to identify it, and methods for removing it safely without harming yourself. 

What Are The Different Types Of Mold? 

Before we get into the nitty-gritty of this post, I thought it would be beneficial to describe the different types of mold that are commonly found in homes. From knowing this, you’ll be able to identify the mold a lot easier, making the cleaning and prevention methods much more powerful. In the world of mold, there are six different types. Here’s what they are: 


We thought it would be best to describe this one first, as this is commonly referred to as “black mold”. It’s one of the most dangerous types of mold, and it causes headaches, diarrhea, severe respiratory damage, and various other flu-like symptoms. The name “black mold” originates from its appearance because it’s the darkest/blackest mold you can find.  


If your home has recently encountered water damage, then Chaetomium can occur. It can look relatively similar to black mold, but the symptoms are less severe. These include having trouble breathing and encountering watery/red eyes. 


This next type of mold is found in most climates today. Nonetheless, people with a compromised immune system can receive some issues like lung infections and allergic reactions. 


Similar to the above, penicillium is found within most climates. However, if it’s trapped within your home, it can cause some respiratory problems. 


This next mold is quite rare to find in households, as it usually develops in plant debris and soil. But, in some cases, it can appear underneath carpeting, foam insulation, inside drywall, and in HVAC systems. Being exposed to this may result in eye infections. 


During spring, alternaria is found in many climates. Typically, it isn’t found in building materials, like many mold types. However, it can be present within the air inside of your home. If you do become subjected to this mold, you may experience a running nose, sneezing, and throat irritation.  

Now you understand the different mold types and the symptoms they can cause, it may be easier to identify what kind of mold is appearing in your home.

Is Black Mold Dangerous?

We briefly mentioned that black mold is the most dangerous mold that can occur in homes, but how dangerous is it? According to the Worlds Health Organization (WHO), air pollution (such as mold) is linked to 7 million premature deaths. From knowing this, we can start to visualize how severe mold really is. To understand the effects of black mold, we go over the symptoms you may encounter if exposed to excess amounts. 

Breathing issues – The most common issue that occurs from black mold is breathing problems. This is because excess amounts of this bacterium can cause respiratory disease, worsen asthma, and increase irritation in vital breathing organs. These are the types of issues you may encounter, and if you already have a weak immune system, you could experience more severe synonyms. 

Skin problems – Something else that black mold attacks is your skin. For those who don’t know, your skin is the largest organ in your body. With most diseases that occur inside the body, it’s also the first indicator that there’s something wrong. Nonetheless, being exposed to black mold can cause your skin to dry and flake. If you encounter this, you can develop large rashes or even worse hives as inflammation worsens around your body. 

Digestive troubles – Additionally to the above, it can also cause many digestive issues like lack of appetite, unwanted weight loss, nausea, stomach pain, and diarrhea.

Excessive mood swings – Lastly, it could affect your mental state. According to this study, around 40% of residents that live in visually moldy households have a 34 to 44 percent higher chance of becoming depressed.

After becoming knowledgeable on the above, I’m sure you’re now aware of the dangers black mold can cause. Because of this, you’ll want to remove it right away. But, although all mold is bad, not all mold needs to be removed with such care, and that’s why you need to identify it. Want to know more about this? Read the following: 

How To Identify Black Mold

The most important thing you must undergo before removing mold is first to identify what it is. From doing this, you’re able to select the appropriate cleaning and safety measures for that specific type of mold. Here’s how to identify black mold: 

Where is black mold found within a household? 

When identifying black mold, it’s probably a good idea to understand where it’s commonly found. From this, if you find a mold-type substance in these areas, you’ll have a head start to identify it as black mold. Black mold is usually found in these areas: 

-Black mold thrives in places that include cellulose. Because of this, you may find it near or on building materials such as drywall and wood. 

-Including the above, black mold gravitates towards extremely damp environments like laundry rooms, bathrooms, air ducts, kitchens, windowsills, etc. 

-Another place you can commonly find black mold is also between sealants and grout. This is because they are usually in high-moisture locations like a shower. 

When it comes to black mold, you can generally smell it before you see it. If you can smell a musty smell in these locations, it’s probably black mold. However, to further conclude this, I suggest you read the below.

When getting up close with black mold, be sure always to wear the correct protective gear. Always wear a face mask, safety goggles, and gloves. After use, be sure to dispose of them. 

Find and Inspect the Color of the Mold 

First things first, find the mold and evaluate its color. Considering it’s called black mold, you probably expect it to be black. However, it can also appear dark green, dark grey, or even brown before it turns into its final black state. 

Black mold can sometimes be mistaken for different mold types. However, they usually appear to have a smaller spore grouping and are targeted to a specific area. 

Locate the Musty Smell 

If black mold is developing, you may not be able to smell it. However, if it’s fully established, you should be able to smell a musty odor from its location. People have commonly said this smell is similar to rotting leaves or dirt. If you’ve found the mold, and you can smell an odor that is likewise described as the above, then it may be black mold. However, to identify this further, consider reading the next step. 

Is it Slimy? 

From undergoing the above, if you believe it’s black mold, you must perform this next step. Most other common household molds have a light texture. However, black mold is much different. Typically, with black mold, it’ll have a slimy or wet feel. To determine this, grab some paper towels and rub the mold infestation. 

However, before conducting this next step, be sure you’re wearing the appropriate protective clothing. 

Added Confirmation 

If you’re still unsure whether or not black mold appears in your home, you may want to purchase a mold test kit for added confirmation. A test kit like this from Seeml Labs will work superbly. This kit is only available for those living in the United States.

To use this kit, you’ll need to swab a sample from your moldy area. From this, you’ll then send it back to the Seeml labs laboratory, and they’ll test for mold. After, they’ll send you an email confirmation of what type of mold is found within your household. Included with this kit, you’ll receive a lab report and free expert consultation.

Considering the price, you’re able to obtain extremely accurate information, which makes it more than worth doing to ensure your household is entirely safe. 

Now you can accurately identify black mold. How does it even occur in the first place? By knowing this, you can prevent the issue from happening again.  

Causes of Black Mold 

Black mold tends to grow anywhere in perfect conditions. The humidity levels must exceed 70% for black mold to grow, but it’s also known to start developing in 60%. In the ideal world, mold looks to grow in warm, dark, and moist climates. The most common area for mold to grow within a household is places like a bathroom, laundry room, windowsills, etc. This is because these household areas can have a considerable fluctuation in temperature, causing mold to grow. 

Mold can also grow very quickly. It’s well-known that an area of mold can grow in just 24 to 48 hours. If left untreated for a prolonged period of time, this small mold coverage can become substantial. 

How To Clean Black Mold Safely  

Depending on how bad your black mold is, you’ll want to choose one of the appropriate methods below. To cover everyone experiencing black mold, we thought it’ll be best to describe three types of cleaning methods. These are with cleaning products, natural processes, and for larger mold patches. 

Before undergoing any of the cleaning methods below, be sure you’re wearing adequate protective clothing. This includes overalls, face masks, rubber gloves, and protective goggles. After use, be sure to dispose of all your PPE. 

Cleaning Black Mold with Cleaning Products 

A sufficient way to remove black mold is with Borax. This laundry detergent is inexpensive and superb for cleaning mold. It works on nonporous surfaces, wood, and various other porous surfaces. If you’re going to use this laundry detergent on a porous surface, make sure they are not damaged by excessive moisture.

  • Before scrubbing, mix 1 cup of Borax with a gallon of water 
  • After, dip a scrubbing brush into the mixture and begin cleaning the mold
  • Wipe the excess mold from the area
  • Once finished, don’t rinse the area dry as the Borax will prevent black mold from appearing again. 

If you cannot gain access to Borax, I recommend using the below materials and following the above instructions: 

Laundry Detergent

Including Borax, other laundry detergents will also work well on nonporous surfaces. 


   This cleaning product is another one that is superb at cleaning mold from nonporous surfaces. 


You can create a spray out of ammonia, and it works great with removing mold from glass and tiles.

Baking Soda

This last chemical works well with both porous and nonporous surfaces to clean mold. 

Using Natural Methods To Clean Black Mold 

Now, I understand that not everyone is keen on using chemicals because of their repercussions on our environment and planet. But, don’t worry, we have you covered. Below we detail how to clean black mold using natural products. 

The most prominent way to remove mold with natural products is with hydrogen peroxide. Here’s how you’re able to achieve this:

  • The best type of hydrogen peroxide is something that entails around 3% of the substance. Once purchased, you can then begin the cleaning.
  • Fill a spray bottle with the solution.
  • After, spray the moldy area and wait to allow it to sit for 20 minutes. 
  • Proceed to wipe the area clean.

Above is the best natural method you can opt-in for when it comes to cleaning mold. However, I understand that not everyone has easy access to hydrogen peroxide. If you encounter this issue, consider using the below remedies.

Tea Tree Oil

  Superb method for cleaning mold from a multitude of surfaces


  Another cheap and very effective mold cleaner. 

How To Clean Large Black Mold Patches  

When it comes to cleaning large black mold patches, it can be quite problematic and dangerous. Because of this, the likelihood of hiring a professional is extremely high. Experts recommend that if you encounter black mold patches which are larger than 10 square feet, you need to hire a professional. This is because if black mold becomes that established, household cleaning solutions won’t be potent enough to eliminate it. 

Once you’ve delegated a professional to clean the mold, they’ll probably remove certain building materials which you’ll need to replace. For example, if you have a 10-foot mold patch on some plasterboard, they’ll safely remove it rather than treating it. Because of this, it’ll need to be replaced to return that area to its original state. 

After replacing the materials, make sure the reason for mold growth is repaired. The most common reason why mold grows is because of humidity. Typically, this can be caused by a warm environment and a leaky tap. If that’s just the climate of that room, consider investing in a dehumidifier, this should solve the problem. 

After reading the above, you should have a general idea of how to resolve your black mold issues. However, once they are fixed, you ideally don’t want it to return. If you’re going to achieve this, consider reading the below prevention methods: 

6 Ways To Prevent Black Mold Growth

It’s known that 50% of American households have some sort of mold present within them. This number is astronomical, and it’s because people don’t understand the development process of mold. Nonetheless, below you should be able to gain a better visualization of this. Here are the main ways to prevent black mold from growing in your household: 

1.Measure Indoor Humidity Levels  

We briefly mentioned above that black mold adores conditions of around 60+ percent of humidity. From knowing this information, we can quickly put prevention methods in place to ensure mold doesn’t stand a chance to grow. 

We briefly mentioned above that black mold adores conditions of around 60+ percent of humidity. From knowing this information, we can quickly put prevention methods in place to ensure mold doesn’t stand a chance to grow. 

By investing in a thermometer, you can determine if a room has too much humidity within it. Ideally, you’ll only want to place this device in rooms subjected to high humidity levels. By doing this, you’re able to regularly check whether or not the room’s humidity level is above 60 percent. 

If you encounter humidity levels of this percentage, you can then act on the issue. This may be to improve the room’s air circulation, or even add a dehumidifier, etc. 

2.Keep Your House Water-free

The simplest way of keeping your house free from black mold is to keep it dry. When you spill water, mop it up. If a leak occurs, fix it. The same goes for wet items. Let’s say you get caught in a rainstorm, don’t just leave your damp clothing and umbrellas huddled up together. Instead, try to dry them in a controlled environment.

The above is especially important for homes that are carpeted. This is because carpets love to absorb water, meaning they are more subject to mold. This includes any spillages on a carpet; ensure it’s fully dry to ensure no mold builds up underneath. 

3.Clean Your Gutters 

The primary purpose of rain gutters is to filter the rain from your roof and extract it away from the property. Therefore, ensuring there are no blockages in your rain gutter as this is how water could potentially find its way into your home. 

If you commonly see rainwater infiltrating your home during a heavy downpour, this may be the reason why. This type of solution will usually prevent mold from building up in areas like an attic. Needless to say, it’s undoubtedly a superb prevention method that you should undergo regularly. 

4.Inspect Your Home Regularly  

To prevent mold, you should also inspect your home regularly. What I mean by this, is that you’ll want to understand the levels of humidity and have a visual understanding of where mold could present itself. By knowing both of these, you’re able to monitor your home and search for any mold building up. 

From monitoring how your home is looking, you can act on the issue before it becomes a mold problem. For example, if you regularly check the humidity in your laundry room, and you notice it increasing above 60%. Then you can implement humidity control methods to lower this and prevent mold from appearing. 

5.Supply Proper Ventilation 

It would help if you considered supplying adequate ventilation for a specific area that is subjected to mold growth. Let’s take a bathroom, for example. A bathroom is a breeding ground for black mold because of its constant change in temperature and moisture from when people take showers or baths. 

To decrease the chances of mold growth, you should install a ventilation system that extracts the moist air outside. By doing this, you’ll dramatically reduce the humidity levels found in the air, ultimately minimizing the chances of mold appearing. 

6.Invest In A Dehumidifier 

An investment that will massively decrease the chances of black mold or any mold occurring is a dehumidifier. Simply a dehumidifier removes excess water from the air, which you’re unable to prevent, and helps control the humidity level of your home. 

However, running a dehumidifier can be somewhat expensive at times. Because of this, it’s suggested you combine both a humidity thermometer and dehumidifier together. This way, you can use the dehumidifier when the humidity levels increase or become too high. 

As you can see, there are various prevention methods that you can implement today to minimize the possibility of black mold occurring. The only thing left to do now is to action the above prevention methods. 


After reading the above, you should have become knowledgeable on black mold. We discussed the reasons for black mold appearing in your home, removing it, and various prevention methods to reduce it from occurring. Now you understand this, you can now act on the issue and live in a mold-free household. 

Kenneth Wilson
August 6, 2021

Kenneth Wilson

Retired contractor. Currently residing in Southwest Florida. Now in semi-retirement, I write and manage this blog focused on helping home owners make savvy decisions when it comes to finding contractors and getting their projects done. I also operate remodeling design service for homeowners.

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