How to Kill Mold in Carpet

How to Kill Mold in Carpet

Mold growing in carpet can be stubborn. Carpet is a porous material prone to absorbing moisture, which makes eliminating every part of fungus growth more of a challenge. Homeowners and the owners and managers of commercial buildings should resolve the underlying moisture problem and determine the extent of mold damage before attempting cleanup. Learn more about the most effective ways to get rid of mold in carpet.

Identify and Stop the Source of Moisture

Moisture is the major factor that causes mold to start growing. Sudden major water damage due to pipe breaks or appliance malfunctions or more gradual damage caused by plumbing or roof leaks can saturate carpets.

Carpets may be made of organic materials, including the plant fiber called cellulose. Fungi are capable of metabolizing this ingredient into starches and sugars to support ongoing growth.

The first step toward managing carpet mold involves arranging for appliance, plumbing or roofing repairs. Resolving the underlying issue is essential for mitigation, or keeping damage from getting much worse before cleanup and remediation take place.

Flooring may also mold due to conditions underneath carpets, such as high levels of moisture in a subfloor or crawlspace. In this case, damage may go beyond carpet to include padding and underlayment. A professional mold inspection can be useful, and you may also want to seek out the opinion of a flooring specialist.

In cases that involve elevated levels of subfloor moisture, mold cleanup should take place first. It may be necessary to tear out and dispose of contaminated carpet or any flooring materials that cannot be completely cleaned, as residual traces of mold can lead to recontamination.

Experts may recommend installing anti-moisture polyethylene sheeting or using other treatments and materials to prevent fungus growth under floors. Until this problem is resolved, mold may continue to grow on carpet.

In the case of gradual roof or pipe leaks, a property owner should have a structure inspected to determine the degree of primary water and secondary mold damage. Thermal imaging can detect the path moisture has taken, which can be useful for estimating the size of a mold infestation.

Assess the Extent of Mold Growth In Carpet

A visual assessment of the surface area of a carpet affected by mold is the only safe measurement method for property owners. Additional safety precautions are needed to determine the depth of an infestation.

Attempting to pull back or remove carpet without putting on personal protective equipment or containing the affected area can lead to exposure or spread spores. Either way, moving or agitating moldy materials can intensify the allergenic or toxigenic effects of mold on occupants.

If you plan to check under carpet, consider covering wall or floor vents with plastic sheeting to limit the spread of spores. Some specialists suggest using a pump sprayer to mist the carpet surface with water to discourage the spread of spores.

Experts recommend contacting certified mold cleanup services for infestations of more than 10 square feet of any structure. If you suspect that mold may be allergenic or toxigenic, it is also a good idea to rely on mold remediation professionals to set up containment, remediate damage and prevent recurring infestations.

Remove Mold Growth and Treat the Area

The first step toward cleaning up carpet mold involves eliminating every sign of growth. Contain the affected area to prevent spores from spreading through ventilation equipment. Remediation professionals use single or double layers of polyethylene sheeting.

While you can use a brush to remove excess mold from the surface of carpet, a wet-dry vacuum is the best way to extract spores. For the best results, consider running an extender tube to a vacuum through the seal in a window opening around a box fan that is venting contaminated air outdoors.

Once you have removed as much mold as possible, it is time to treat the affected area. Always test homemade or store-bought carpet cleaning solutions in a discreet area, such as the carpet under a piece of furniture.

It is possible to kill most carpet mold with full-strength or diluted vinegar in a solution of one part vinegar to two parts water. This natural cleaner is not as harsh as bleach or some fungicides but also has a pungent odor. Adding a few drops of essential oil may mask the odor of a vinegar-based solution, which will diminish over time.

You can also dilute one part sodium borate, which is sold as Borax, in 16 parts water. To make a gallon of this alkaline cleaning solution, add one cup of Borax powder to a gallon of warm water.  Other effective carpet cleaners combine one-half cup of Borax powder with one-half cup of white vinegar and one cup of water.

Baking soda can also be combined with vinegar to make a potent foaming cleaner. Baking soda is alkaline and vinegar is a mild acid that can be combined to produce an intense bubbling reaction that can penetrate carpet fibers to eliminate mold.

Hydrogen peroxide also produces a bubbling reaction but may discolor carpet. Mix one part hydrogen peroxide to two parts water and fill a spray bottle with the solution. Be sure to spot test any cleaning solution containing this ingredient in an inconspicuous area. Spray carpet and wait five minutes before blotting dry.

Bleach is not the best choice for killing mold on carpet. This caustic cleanser can discolor carpeting and cause fibers to break down. Furthermore, bleach is a surface disinfectant that may not penetrate into porous materials to kill the hyphae and mycelium.

Fungicides are the best options for stubborn mold infestations that do not respond to household cleaners. It is also important to test these substances and avoid contact with sensitive occupants, such as children or pets, and divert traffic over these areas.

Blot and Dry the Affected Area of Carpet 

Once you have treated moldy carpet, blot the treated area with paper towels or a clean, absorbent cloth. This is just the first step toward reducing moisture levels after cleaning. It is important to increase air circulation to allow an area to dry completely. Afterward, check back over the next few days to determine whether any signs of regrowth become apparent.

For faster drying, you should use a new fan that is not contaminated with mold spores. A dehumidifier can also be helpful for drawing moisture out of porous materials, such as carpet. If signs of mold are still evident after treatment, it may be necessary to reapply cleaning solutions or fungicides or seek out professional carpet cleaning or mold remediation.

The source of water damage is a critical factor for determining how easy is to clean and keep carpet that has supported mold growth. Moisture working its way up from under flooring may require the removal of flooring and installation of a watertight barrier in the form of a layer of polyethylene sheeting.

Moisture coming from broken or leaking pipes or a roof leak tends to work its way down to carpeting. It may also be necessary to clean and dry walls and baseboards after this type of damage. Most leaks in a structure start as contaminated Category Two gray water but can degrade into grossly contaminated Category Three water after soaking through building materials.

The presence of toxic mold in a structure may necessitate the replacement of carpeting, drywall, insulation or other porous building materials. Further treatment, such as air filtration with a carbon medium or an ozone treatment, may be necessary to break down mycotoxins. Consult with trained remediation professionals regarding the toxicity level of mold and the requirements for a complete cleanup.

Consider Retreating or Replacing Carpeting

If an initial white vinegar or Borax treatment is not effective, a property owner should weigh the pros and cons of attempting another DIY mold removal treatment. The longer mold is permitted to grow in a structure, the more severe an infestation may become, leading up to a more extensive and expensive professional cleaning.

Mold remediation experts can help homeowners and commercial building owners make informed decisions about attempting to clean moldy carpet. In some cases, the cost of replacing the carpet may be less in terms of money and time than repeated cleanup attempts. In other cases, natural cleansing solutions, such as vinegar, may not kill a particular type of mold.

It is impossible to identify the species of mold growing on carpet without professional testing and lab analysis. Air, batch or surface samples submitted for lab analysis can be positively identified, along with the allergenic or toxigenic status of an infestation.

In general, carpet that is supporting toxigenic mold should be replaced. It is also worth noting that while most mold cleaning solutions kill spores and reduce the amount of microbial volatile organic compounds released into the air during the growth cycle of colonies, toxigenic compounds can linger in a structure even after cleanup is complete.

When To Seek Help From Mold Cleanup Experts

If an infestation appears to affect more than 10 square feet of a structure, a property owner should arrange for a professional inspection. The size of the area affected by mold and the type of mold in a building will determine whether limited or full containment are necessary to safely clean up mold on carpet or other building materials.

Depending on the extent of an infestation, plastic sheeting and professional methods for creating negative air pressure with a decontamination chamber may be necessary to stop the spread of spores. Limited containment only requires a single layer of sheeting, whereas full containment requires double layers, negative pressure and an airlock.

Toxic mold can be difficult for non-professionals to handle safely. In many cases, it is necessary to tear out, bag up and dispose of carpet and other porous materials contaminated with a toxigenic fungus species. Surrounding materials may be better candidates for cleaning, and the damaged materials can be replaced during the remediation process.

If the entirety of a mold infestation only affects a small area of carpet and does not seem to be causing negative health effects, this infestation may be a good candidate for a do-it-yourself cleaning attempt. Always wear personal protective equipment, such as a face mask or respirator rated to filter out mold spores.

In terms of carpet cleaning treatments, distilled white vinegar is one of the most effective household solutions. If treating mold with a full-strength vinegar or a mixture of vinegar and water in a one-to-one ratio or one-to-two ratio is not effective the first time or after a repeated application, you may want to seek out a mold removal service.


  1. Is it possible to get mold out of carpet?

It may be possible to clean moldy carpet infested with non-toxigenic species that pose lower allergy risks. Carpets contaminated with toxic black mold are more difficult to clean. In these cases, or for infestations that have spread over more than 10 square feet, carpet replacement may be a better option.

  1. How long does it take for mold to grow in wet carpet?

Mold may start to grow on saturated carpet in as little as 48 to 72 hours, or two to three days. Carpet often contains cellulose. Regardless of the composition, carpet fibers trap dust and spores that have the potential to support fungus growth even if you vacuum on a regular basis.

  1. How do I know if my carpet is moldy?

A musty odor in a structure or visible discoloration on the carpet in a place where no spill has occurred are the first signs of carpet mold. Mold may be yellow, black, green, brown or white in color and fuzzy in texture. Consider seeking a professional opinion on mold cleaning or removal.

  1. Will carpet mold if it gets wet?

Damp or wet carpet is prone to develop mold. Some carpet contains cellulose or other organic fibers that support mold growth. Dust and spores accumulate in fibers. Carpet holds in moisture and may worsen mold that affects lower levels of flooring such as padding, sub-flooring or underlayment.