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How To Get Rid of Mold on Floor Joists in Crawl Space

How To Get Rid of Mold on Floor Joists in Crawl Space

Mold can grow anywhere where the conditions are right, and it is common to find them on floor joists in crawl spaces. Mold remediation costs for such spaces are less expensive than basements and are sometimes used as an alternative to allow access to the bottom of a home, especially in places where the weather tends to stay dry. However, a crawl space can all too easily collect moisture and become a breeding ground for mold.

The Growth of Mold in Your Crawl Space

Unless your crawl space is adequately insulated and ventilated, you may find mold starts to develop there. When you do finally spot mold underneath the house and creeping along the floor joists in the crawl space, it could mean there is a bigger problem in the upstairs areas of your house as well. Early detection of mold is vital to keeping colonies of growth at bay.

Removing mold from a crawlspace is dangerous and should be handled by a Mold Remediation specialist. Call us at (877) 349-1231 for a free consultation with a licensed remediation expert available 24/7 near you.

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Early Warning Signs

Once it starts growing, mold is able to spread very quickly, so it is important you know what it looks like, where it coming from, and what are the best remediation approach. With over 100 species of mold capable of growing in the U.S., there are many possible warning signs of an infestation. Here are some of the more common things to look for when assessing if your crawl space has a mold problem:

1. Musty smells

As mold spores grow into a large colony, a musty, damp odor typically develops. You will probably detect this odor before you are able to see the growth. The scent coming up from the crawl space may be noticed inside the house or around the vents or entryway to the area beneath the house. Even if you use fresheners, it is nearly impossible to hide the smell of mold.

2. HVAC problems

Mold in the crawl space can spread into the HVAC system. It may travel up through the air ducts of the home, filling the house with an odor and depositing spores in new areas for growth.

3. Structural damage

The organic materials of your home are the source of life for mold, leading to the deterioration of wood, paper, fabrics, or glue as the colony of mold grows and feeds. Over time, mold can cause enough damage to the supports and materials of the crawl space to threaten the safety and structural integrity of your home. As mold moves across the floor joists or up into the floorboards, it could cause the ceilings above to collapse, the floors to crack or cave in, and the walls to crumble and fall.

4. Health Concerns

Mold beneath the house can still affect the health of those living inside the home. Mold spores aren’t confined to a single area, as they can spread through the air. Inhalation of these spores and living in a mold-rich environment has the potential to jeopardize your health and leave you feeling miserable. Exposure to these funguses often leaves individuals with unrelenting allergy symptoms, especially for those with more significant allergies.

Exposure symptoms can mimic an upper respiratory infection, with individuals experiencing excessive sneezing, a runny or stuffy nose, cough, postnasal drip, sinus irritation, and skin rashes. The severity of the exposure impacts the potential symptoms. If your health improves when you are away from home yet seems to immediately decline when returning, you could have a problem with mold.

Crawl Space Mold Varieties

There is more than one type of mold that can be lurking along the floor joists or in the crawl space. Knowing what you are dealing with helps you decide on how to get rid of the mold and fix the problem.

It is likely that if mold is present in the crawl space, you will find clusters or patches of white dirt or powder on the girders, posts, or floor joists. These species have a fuzzy appearance and are more commonly found in the spring, summer, or fall months. Black mold varieties are not fuzzy or powdery, generally appearing as a flat, greenish or dark gray patch. Yellow mold can eat at the wooden structures of your home and cause serious decay. Here are the four most common types of mold found in a crawl space:

1. Stachybotrys

This is commonly known as black mold, and it is one of the most toxic species that you could find in your crawl space. Insulation or sub-flooring that has gotten wet or exposed to moisture, as well as carpet, drywall, or beams, are places where you can find black mold. While there are several other strands that do have black coloring in the growth, a distinctive black color, combined with the odor and presence of moisture, should be treated with extreme caution. It is always advised to let a professional mold remediation crew handle black mold.

2. Penicillium

This strand’s name sounds a lot like penicillin, the life-saving anti-microbial treatment, because it had a significant part in the development of the medicine. Crawl spaces with dirt floors and decaying vegetation are prime for the growth of this type, which can cause breathing problems to those who are allergic to the harmful toxins.

3. Cladosporium

This is a potent species of mold that can have devastating health consequences. It prefers to feed and grow on soil, painted wood, woody plants, clothing, paper, HVAC systems, painted walls, and mattress dust. Though you may not have most of these items in your crawl space, a few mold spores can quickly multiply and spread to other areas of the house and contaminate them.

4. Aspergillus

This is perhaps the most common mold found in homes and crawl spaces. These spores aren’t considered as dangerous as some of the others, but there is still concern that long-term exposure can create sinus irritation, acute or chronic lung infections, and allergic reactions. This species can grow indoors, thriving in HVAC ductwork and damp crawl spaces, as well as outdoor spaces.

7 Steps for Cleaning Mold on Floor Joists in Crawl Space

Tackling mold in the crawl space and along the floor joists is a physical job. It takes a lot of scrubbing and the ability to squeeze into tight spaces. Because of these working conditions, you need the property safety gear and cleaning agents to get the job done quickly and without jeopardizing your health. Have the following personal protective equipment:

  • Goggles
  • Textured-grip material gloves
  • Respirator or dust/chemical mask
  • Protective clothing

You also need to gather cleaning supplies:

  • Plastic sheeting
  • 5-gallon buckets
  • Spray bottle
  • Sponges/old cloths
  • Brush, putty knife, or small shovel

Before proceeding, you need to decide on what you are using to clean up the mold you find in the crawl space. Some individuals choose to make their own household solution cleaners. You can use ammonia, bleach, tea tree oil, or vinegar to remove the mold. You can also purchase a commercial-grade cleaner, such as a mold remediation company would use.

Whatever you decide to use, you need to be thorough and systematic in your approach to getting rid of the fungus. Here how to get started with mold removal:

  1. Put on your protective clothing, gloves, or goggles before mixing up your cleaning solutions.
  2. Follow the recommended solution measurements for mold removal. You can use two parts baking soda, one part white vinegar, and one part water to form a paste to coat the contaminated area with. If you have a large area of growth, you may want to use an acid-based cleaner like vinegar that is easier to spray. One cup of Borax to one gallon of water is a strong solution that is still safer than bleach or other has chemicals. Bleach is an affordable solution; to dilute it for safety, mix one quart of water with half a cup of bleach.
  3. Cover any openings, such as air conditioner vents or doors, with plastic sheeting. This keeps down on the spread of mold spores throughout the house. You also want to make sure there is ventilation in the crawl space while you are working with strong fumes or chemicals. Set up a fan blowing the air towards the outside or away from where you will be working. This creates ventilation and allows the moisture to be eliminated more quickly.
  4. Using a small brush or the flat part of a putty knife, scrape off or remove any large growths of mold that you see. You can scrape these into a trash bag or let them fall to the floor. You will be disinfecting the dirt once you are finished with the floor joists and other spaces.
  5. Spray the entire affected area with the cleaning solution of your choosing. Soak the area, but not so much that you create permanent wood damage. Allow the solution to sit and soak on the affected area for at least five minutes before you start scrubbing it. A brush is best to use on any wooden surfaces, as splinters from the wood can pose a safety hazard and they can cause a cleaning cloth to snag. Continue to scrub the surface until all the visible mold has been removed.
  6. Spray down the dirt on the floor with your cleaning solution as you exit the crawl space. This helps kill any mold spores that may have fallen onto the floor, preventing them from growing back. Vinegar, bleach, and other solutions will evaporate, but they can kill up to 90% of any fungus that has found its home in the crawl space. Hard-to-reach spaces can be decontaminated with a spray bottle or a pump sprayer.
  7. After you have scrubbed and doused the contaminated areas, put a UV lamp into the space to help kill any remaining spores. Let the light shine on the dirt floor for at least a whole day. In addition to killing the mold, this helps dry out the space, helping prevent further growth. Use fans to circulate the air and blow out any odors from the mold or cleaning solutions.

Assessing Damage From the Mold Growth

The dangers of mold to your home go far beyond health concerns. If mold is left unaddressed, you run the risk of serious damage to the floor joists, floorboards, and other support structures of your house. Wood that retains moisture is weakened, and an invasion of mold takes the damage even further. The boards and beams can crack and separate as the fungus eats through the materials. You may not know that your flooring is unsafe until it’s too late.

After you have thoroughly cleaned up the mold, you need to assess the area for damage. Look at the joists or boards and determine if there are soft spots or areas of deterioration. You want to have any structural concerns evaluated by a professional contractor, as you may need some parts of board, beams, or flooring replaced for safety.

Paying for Mold Remediation

For those who are going to DIY their mold problem, the costs include purchasing cleaners, tools, and personal protective equipment. This is generally a more affordable option than calling in mold remediation specialists, but you may not be thorough enough in your cleaning. This could lead to a recurring mold problem down the road. Bringing in the professionals may be a better investment in the long-term.

The size of the mold contamination, as well as the materials that have been damaged or infected by the spread, impacts the cost of removal. Access to the area and the extent of the damage as also significant factors. Smaller infestations could cost as little as $500 for removal services, while more severe problems can cost upwards of $30,000 for complete treatment and repair of the crawl space or floor joists. Unfortunately, most homeowner’s insurance policies will not cover remediation services unless the infestation can be linked to a covered incident like water damage or flooding.

For experienced help with removing mold from your crawl space, contact the team at Mold Remediation. They are experts at removal and cleanup services for both residential and commercial buildings.

Mold Inspections

Hiring a professional mold inspector will give you peace of mind. Being in a position where you are uncertain as to the toxicity of mold in your residence can be extremely stressful.

At, we pride ourselves on being quick, thorough and effective in how we communicate the mold remediation tests that we perform for our homeowner clients.

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