How to Get Rid of Mold in the Basement / Crawl Space

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You walk into your basement and find a patch of mold growing! What do you do? Mold growth can be a serious issue, but knowing how to get rid of mold in the basement will help you avoid hazardous conditions it may bring. A mold outbreak isn’t just unsightly, it can slowly damage the structure of your home and pose serious health risks to you and your family.

It isn’t difficult to recognize when you have a mold problem. One of the first signs is a strong, musty odor. Mold can have a slimy, fuzzy, or powdery appearance and different varieties present with different color variations. In homes with a crawl space you may notice a musty smell or find mold along the baseboards. The crawl space is not likely a place you regularly visit so mold growth may go unnoticed until it starts to permeate through the floorboards.

What Causes Mold in the Basement?

Man in hazmat suit looking at mold on wood in basement.Man in hazmat suit looking at mold on wood in basement.Man in hazmat suit looking at mold on wood in basement.Man in hazmat suit looking at mold on wood in basement.
Make sure you wear a respirator when working around mold.

It comes as no surprise that mold in basements and crawl spaces is a common issue many homeowners face. This ground level of your home presents the ideal environment for mold to grow – a dark, damp space with limited airflow. Basements are susceptible to excess moisture often resulting from a number of factors:

  • Built-up condensation
  • Leaky foundations
  • Sump Pump failure

Basements typically have poor ventilation. While mold spores do require oxygen to grow, limited air flow in undisturbed areas of your home can easily become a breeding ground. It can grow very rapidly and eventually spread to other areas of the home.

One of the first steps in getting rid of mold in basements is to identify the source of the cause. One of the biggest contributors is excess moisture. Search for any potential factors that are causing the excess moisture in your basement. Leaky pipes are a common problem in basements simply due to their functionality. Over time pipes become susceptible to breaks and leaks from wear and tear. This occurrence can happen even in homes built with high-quality foundations.

If your home has a basement you might have a sump pump installed. This appliance is responsible for pumping out standing water in basements when detected. A built-in sensor and a floater activate the pump when water reaches a certain level. If this pump fails it can easily be linked to issues in water drainage and create a big problem.

Once you are able to locate the source of the excess moisture take the necessary actions to fix them. Repair leaky pipes or call in a professional to inspect and repair a sump pump malfunction. Take action to control the climate in your basement to prevent built-up condensation.

Is it Mold or Mildew? What’s the Difference?

The most common forms of fungi found in homes are mold and mildew. These two forms of fungi have very similar qualities and both can be harmful. Knowing the difference, however, is important when it comes to proper cleaning and removal.

Mildew is typically grey or white in appearance. Mold, on the other hand, can be black, red, brown, green, or any combination of these colors. Mildew grows only on the surface of the material it builds on. You typically find mildew on damp surfaces such as duct-work, shower doors, and refrigerators. It can also grow on various materials such as fabrics, paper, and organic surfaces such as plants.

There are two classifications of mildew- the downy variety and powdery mildew. The downy variety appears as yellow dots that turn brown gradually. Powdery mildew starts off looking like white or gray patches that are fluffy in appearance. These patches eventually turn to a yellowish-brown shade or black. Mildew is commonly identified by its flat, growing pattern that spreads across the material it is growing on.

Unlike mildew, mold can penetrate the surface of the material it is growing on and is much more hazardous. Over 10,000 species of mold can be found inside your home according to the CDC. Mold can form in a combination of colors from white, black, red, green, brown, yellow or blue. It will have a fuzzy or slimy appearance and damages the surface of the material it grows on. Mold typically forms in irregular patches. The most dangerous form of mold is Stachybotrys Cladosporium, also commonly known as black mold. This form of mold produces toxins that have been linked to a wide range of respiratory conditions.

Mildew is much easier to clean than mold because it only grows on the surface, therefore it can be easily wiped clean. You simply need a cleaning solution that consists of vinegar or bleach to wipe the surface. Mold requires more deep cleaning and once it penetrates the surface of the material professional mold removal may be necessary.

Various Types of Mold

Diagram of black mold.Diagram of black mold.Diagram of black mold.Diagram of black mold.
Black mold is one form of mold.

There are many strains of mold that can occur in your home. If you want to know how to get rid of mold in the basement, a good place to start is by identifying which type you are dealing with. Identification is essential so you can adjust your solution accordingly to correctly remediate the problem.

Alternaria – This type of mold is found indoors and outdoors. This strain of bacteria grows easily in dark, dimly lit spaces. If your lower floor has a sink or bathroom it is certain to grow. Possible symptoms from this bacteria may cause allergic reactions or bring on asthma attacks.

Aspergillus – This strain of mold commonly occurs indoors and appears green. This spore has likely developed in most homes at some point over time. Possible symptoms from this fungi may cause allergic reactions, inflammation of the lungs, and respiratory infections.

Aureobasidium – This form of mold growth has most likely appeared in homes with old wood. When it grows it has a pink appearance with black spots or can be brown. Possible side effects from the fungus can easily cause allergic reactions to develop.

Stachybotrys Chartarum – Also known as Stachybotrys Cladosporium this is the infamous black mold that can grow in air ducts and pipes. It can be easily distinguished by its musty smell. Exposure can lead to serious respiratory problems. Professional remediation is recommended if you identify black mold in the home.

Trichoderma – This indoor strain of mold can be found in damp surfaces like carpeting, wallpaper and other possible porous surfaces. Symptoms from exposure to this type of mold are similar to those you might experience with black mold.

Ulocladium – This bacteria occurs both indoors and outdoors and is common in basements after experiencing flood damage. Symptoms from this mold growth can cause allergic reactions and possibly infection.

Mold exposure can cause a variety of symptoms to develop associated with an allergic reaction including irritation to the eyes, weakens the immune system and can trigger asthma attacks in individuals with asthma and lung-related conditions. If you or someone in your family have been experiencing these symptoms it might be due to a mold infestation in your basement or crawl space.

How to Kill Mold

Woman upset about mold on her basement walls.Woman upset about mold on her basement walls.Woman upset about mold on her basement walls.Woman upset about mold on her basement walls.
Nobody wants to see mold inside their house.

Commercial mold-killing products are the most effective and generally offer better stain removal from residue. We suggest Concrobium. This is a popular and well-trusted brand when it comes to mold removal. It comes in various forms to get the job done and works really well for odor removal while also preventing future regrowth. There are other alternatives you can use that you may already have in your home.

Organic Mold Removal Products

One of the best options for an organic DIY mold killer solution is vinegar and baking soda. Cleaning vinegar is recommended. A mixture of vinegar and baking soda will eradicate black mold without releasing harsh fumes in the air. To create a solution you will need 1 cup of vinegar and a couple tablespoons of baking soda.

Borax can also be used to remove mold and mildew stains from porous surfaces and inhibits future mold growth. Borax is a natural mineral powder that is commonly used in cleaning and also makes a good deodorizer. It can be used with vinegar and water as a more effective method. To make a solution with Borax powder follow a ratio of 1 cup of powder with 1 gallon of water. Mix until the powder is completely dissolved. Hot water is recommended to ensure the powder dissolves. This mixture can be used as a spray simply by adding to a spray bottle or applying by using a rag or cloth.

Using Bleach for Mold Removal

Chlorine bleach is a common household cleaner many people have on-hand and it is commonly used for cleaning mold and mildew. There are a couple of things you need to understand first about using bleach for mold removal. This home-made solution will work but is recommended ONLY on non-porous surfaces such as glass, tile, shower doors, etc. It is not recommended on surfaces such as drywall or wood as it can not kill mold completely in these materials.

Bleach does not kill all types of mold so if you are planning on using this as a solution it’s important to identify the type of strain you’re dealing with. If you suffer from a respiratory condition such as asthma, using bleach as a cleaning solution can exacerbate breathing problems. Do not mix bleach with other combinations of cleaners as this can create toxic gases when mixed together.

Oxygen bleach is a better alternative at killing mold in an environmentally friendly composition. This form of bleach typically comes in a powder form which you mix with water then breaks down into hydrogen peroxide and sodium carbonate. It effectively kills mold and bacteria while also working as a good deodorizer.

How to Get Rid of Mold in the Basement

While calling in the professionals is highly recommended when dealing with more serious forms of mold, there are a few steps you can take for DIY mold removal. Before getting started you will need to make preparations by having the necessary supplies for the job and removing furniture or moving appliances. Part of the mold removal process also requires dehumidification to pull out excess moisture. You will need an air purifying dehumidifier or an air conditioner with a built-in dehumidifying function.

►NOTE : Read our guide of buying a dehumidifier for your basement or crawlspace

Safety gear is a must when dealing with black mold for your health and safety. This will require the following:

  • OSHA-Rated respirator or face mask
  • Non-vented goggles
  • Heavy-duty gloves
  • Disposable coveralls

Next you will need to arm yourself with the necessary supplies for mold-removal and cleaning such as scrubbing brushes, rags or disposable cloths, sponges, spray bottle, mold-killing cleaning solution, and a dehumidifier or portable air conditioning unit.

You will need to have adequate access to the walls and floors of the basement to properly get rid of any strains of fungus present. This means you will need to move appliances away from the walls and remove furniture or additional items as necessary. Any items that are contaminated with mold will need to be thoroughly cleaned with a solution or treated with a commercial cleaner as well. Inspect all pieces for visible mold residue as you remove them. You may need to throw out any contaminated pieces that have black mold to ensure the spores don’t spread.

Use a dehumidifier or an A/C unit to draw out all of the excess moisture and dry out the damp space. Since mold spores grow under excess moisture conditions this step will help stop the growth of spores. You should also open any windows that you can and run an exhaust fan to generate good air flow in the space. 

Depending on the duration the mold has been present you may need to ‘soak’ the affected area first. Airborne spores can create hazardous air quality so by carefully saturating the surface prior to cleaning it will help in keeping the bacteria from breaking into the air. Lightly spray the surface with a mold-killing solution using one of the suggestions mentioned above.

Soak the tools you will use to wipe the area such as a brush or rag with your solution first. Then scrub and clean off the visible grime as thoroughly as possible. When you are done, dispose of all of the cleaning tools that came into contact with the spores.

How to Get Rid of Mold in a Crawl Space

Removing mold from a crawl space is not quite as simple as getting rid of mold in the basement. It’s a little more time-consuming process, but necessary to ensure you effectively remove as much mold residue as possible for a cleaner, healthier home. Before you begin you should have the proper safety gear as previously mentioned. You’re going to need additional tools for cleaning and removal such as lights for visibility, plastic sheets or drop cloths, stiff bristle brushes, a foaming spray cleaner, and mold-killing solution.

The first step before you begin is to place lighting for optimal visibility of the area you will be cleaning. Next, place plastic sheets or plastic drop cloths down to catch the mold that falls as you are cleaning the surface. Use a foaming cleaner that is specifically designed for mold removal. Foaming spray cleaners cling better to vertical surfaces and expand once applied to the surface, giving you optimal coverage. Allow the foam to expand and let it sit for a few minutes to effectively loosen mold then begin cleaning the surface.

Once you have cleaned the surface and removed the majority of the mold you will need either a commercial cleaning solution or DIY-mixture formulated for killing mold like those previously mentioned. Using the solution, thoroughly saturate any remaining thin coats of mold then allow to dry. Scrub away any remaining mold and residue using a stiff bristle brush. After cleaning, fold up the plastic sheets carefully and dispose of them in a heavy-duty garbage bag. Dispose all contaminated tools and gear carefully as well and keep bagged outside in a garbage collection bin until trash pickup. Install or implement measures to control the climate in your crawl space such as a dehumidifier.

Even if you choose to do the job yourself, it’s still recommended to call in the professionals for an inspection. Not only do they know how to get rid of mold in the basement safely and effectively, they can also perform tests to ensure it isn’t growing in other areas that may not be easily visible.

Tips for Preventing Mold Growth

The biggest threat that contributes to mold growth is an excess of moisture. To prevent mold from growing in your basement take these steps to maintain your space.

If you can, leave the dehumidifier in your basement or crawl space to consistently maintain the air and climate quality. These are especially useful and recommended if your space does not have any windows or means of proper ventilation.

Insulate your pipes. Hire a plumber or contract a professional to properly insulate your pipes that were leaking or sustained damage. It’s also a good idea to insulate the walls and around windows if your basement has any. This will help minimize condensation from occurring.

Keep the space maintained. Make a habit of checking out the basement a little more often to inspect for any potential problems such as leaks. Inspect appliances periodically and have them maintenance once or twice a year for best results.

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