This article is designed to illustrate the differences between mold killing, cleaning and preventative chemicals, and is not to be used as an all-inclusive list of steps for mold remediation. For instructions on how to remediate mold in areas in and around the home click here.

During conversations on mold cleanup there’s one topic that always comes up: the difference between three separate types of mold treatment chemicals and when and how to use them. There’s no reason to get too technical on the subject because common sense is the driving force in solving mold problems. There are three basic types of chemicals that are used in mold remediation:

Mold Killers

The most important are the fungicides, which are typically disinfectants as well. These are also simply called mold killers by many in the industry. The word fungicide means “kills fungi,” and mold is a type of fungi. A mold killer may double as a cleaner or preventative in some cases, but it’s primary purpose is to kill mold and mold spores, so it’s too be used for this specifically when needed. But when is a mold killer needed?

Every surface and material inside and around a mold contaminated area, especially those materials you’re planning to try and save, should be treated with a mold killer (fungicide).

Surfaces that can/should be treated: all porous, non-porous and semi-porous items that the remediator wishes to save, and all surfaces in a full home mold contamination that the remediator is planning to tear out and dispose of should be treated as well before moving them or performing the tear out. This is to limit the amount of living mold spores that are spread around.

Mold Cleaners

Mold Cleaners are simply cosmetic products designed to remove mold stains and make surfaces and materials look clean or cleaner again. The most common cleaner is bleach. While bleach is a very well-liked cleaner because of how efficiently it bleaches out the mold stains and makes them appear to vanish, it’s quite a harsh product with a harsh odor. Many people who deal with mold cleanup on a regular basis opt for safer products like oxygen bleaches, soaps and detergents. Fungicides with surfactants in them can sometimes be used as mold cleaners and scrubbed, brushed or wiped on surfaces to remove stains, but it’s important to recognize the fact that cleaning mold means removing the visible growth or stains and killing mold means using a fungicide to kill the roots, spores and fruiting bodies and stop the growth.

Cleaning mold without chemicals, like using a HEPA vacuum or HEPA air moving equipment to filter mold spores and toxins from the air is a form of mold cleaning that doesn’t directly address the mold stains that may be present, while dry ice, sand or soda blasting can be a very quick and effective way to remove mold stains. These methods can be used in conjunction with other methods or mold cleaning or mold killing, depending upon what the mold cleanup job requires.

Mold Preventatives

There are hundreds of things that can prevent mold growth, but the most important is controlling the moisture that fuels mold growth in the first place. There are many antimicrobial paints, sealants and other special coatings on the market that can add a little more protection against mold growth to many surfaces, but in the end, if moisture isn’t controlled, mold will return. Nothing will prevent mold in the constant presence of moisture.

There are waterproofing and fungicidal sealants on the market for treating decks, siding, fences, crawlspaces and other surfaces, and even zinc and copper strips can be used to prevent mold growth on roofs.

How do I know if I need to use a mold Killer, Cleaner or Preventative?

Before starting any mold remediation project, it’s best to plan a strategy, the safest and most thorough way to go about the job. Sometimes it’s best to treat with a fungicide first and in other cases it’s better to use a cleaner first. Sometimes the simplest treatment will work fine and in others several careful steps should be taken. Keep in mind that fixing the moisture problem that allowed mold to grow in the first place is as important as the actual killing and removal of the mold.

Mold remediation isn’t limited to just killing, cleaning and preventing mold growth. The purpose of this article is to clear up what the difference is between these three ideas. When dealing with mold contamination indoors, especially in living areas like bedrooms, kitchens, etc, it’s almost always imperative to kill the mold with a fungicide. Cleaning may be necessary if there’s visible growth or stains to remove; otherwise there may be no reason to use chemical cleaners. The physical removal of mold spores using HEPA vacuums or HEPA air filtration is almost always mandatory if the mold contamination covers an area larger than 1-10 sq. ft., if there’s a musty odor, if anyone’s been noticing any health symptoms which could have been a result of exposure to mold, or if prior mold testing has shown that there’s an elevated level of mold present. This is a form of mold cleaning, just not using chemicals. Mold preventative chemicals can be applied at the end of the mold remediation project to many surfaces. There are antimicrobial paints and sealants that can be used to treat studs, floorboards, drywall, ceilings, decks, patios and many other surfaces and materials. This isn’t always a necessary step, but when mold remediation is done by homeowners and other DIY’s instead of certified professionals, this step is very helpful. Mold should be treated seriously and remediation should be done safely and thoroughly. Err on the side of caution and mold remediation will always be successful.

Here are some examples:

Crawlspace Mold

Let’s say you have a mold contamination in a crawlspace and the mold is limited to this area, but the growth isn’t covering a few small spots in a corner, but instead the growth speckles the floor boards and joists all across the space. Which, if any, chemicals might you use to help remediate the mold contamination?

Think about simplicity and safety first. Since this is a crawlspace and the mold is limited to this area you may not need to worry about killing the mold right off the bat. Cleanup is typically the first step, same as it would be when treating mold on outdoor surfaces like siding, decks or patios. Remove any insulation that’s present and install a moisture barrier if one isn’t already installed. This is a cleaning step in that you’re removing the insulation that can’t be treated and making it easier and safer to work in the crawlspace. Chemical or mechanical cleaning can be done at this point to remove visible mold growth. Bleaches or other cleaners can be used to remove stains and growth in many cases, but with harsher staining it may be necessary to use a blasting media or sander to remove the stains.

Now that the crawlspace is cleaned out and surfaces have been made more cosmetically presentable there’s room to go ahead and kill the mold roots with a fungicide. Most fungicides are applied using spray equipment, but some can be fogged. This step is imperative whenever remediating mold on semi-porous surfaces like wood, concrete, cinderblock, brick, etc. Mold roots into these materials and cannot just be cleaned off by wiping, scrubbing or sanding. A fungicide is needed to penetrate to the roots and kill the growth.

Once this is done it’s a good idea to apply a fungicidal preventative of some sort, whether a paint or sealant or other type of coating. While this may not be 100% necessary in indoor areas like kitchens or bedrooms, crawlspaces tend to get and stay damp easily, so applying a mold preventative is never taking things too far.

Living Room Mold

Let’s say there’s been a serious roof leak while you were out of town and for a couple of week’s water and mold infiltrated the living room. While there are many steps that should be taken here to ensure the remediation is done safely and successfully, the first chemical you’d use would be a mold killer, a fungicide. When dealing with mold in living areas it’s best to kill as much of the mold growth and spores as possible before going about the cleaning process. This will help limit the living mold spores that get spread around later.

After using a fungicide the cleanup can begin, where bleaches or other cleaners may be used to remove stains, HEPA vacuums and air movers may be used to filter out the air and physically remove mold and spores from surfaces. Drywall and carpet may be cut out and disposed of. Many other steps may be necessary, but one can see that the ideas of killing and cleaning mold are two entirely different things, even though many people use these two terms interchangeably. When treating mold indoors the mold killing and cleaning steps may have to be repeated several times back to back to achieve a result acceptable to the homeowners, so it’s important to understand that just killing and then cleaning the mold may not be enough. You may have to treat with a killer then clean, then treat with a killer again several more times, or even redo the cleanup process depending upon the situation. The idea is, once again, to err on the side of caution. Every mold remediation project is different.

When the cleanup is done and the mold is killed the option to seal or paint studs, drywall, flooring and other surfaces with an anti-microbial product to help prevent future growth is a good idea, although if moisture is controlled, isn’t entirely necessary. In all cases using an anti-microbial product is safe practice.