Spraying a biocide at a mold remediation project (C) Daniel FriedmanHow to Use Disinfectants, Mold Sprays, Biocides, Mold Encapsulants, Fungicides, & Sealant Paints

  • MOLD SPRAYS, SEALANTS, PAINTS - CONTENTS: Disinfectants, Sanitizers, mold spray encapsulants, disinfectants, encapsulants: products, choices, & use guidelines. Mold spray mistakes to avoid. Definition of biocide, disinfectant, sanitizer, sterilize. Guide to using disinfectants, sprays, and paints to control bacteria, mold, or other indoor environmental problems. Recommendation against biocides for mold remediation
  • POST a QUESTION or READ FAQs about how best to use biocides, fungicidal sealants, sanitizers & sprays in buildings as part of a mold contamination remediation job
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Using mold sprays, sealants, sanitizers indoors:

This article discusses the use of sprays to address bacterial and mold hazards in buildings. We illustrate when the use of disinfectant or biocidal sprays, fungicides, bleach, paints, and encapsulant coatings are useful, and when they are a mistake.

This article emphasizes that cleaning or removing problem mold and correcting the reasons why it grew are key steps, adding that consumers should beware of use of sprays of any kind if they substitute for those steps.

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When Is it Good Practice to Use Biocides, Disinfectants, or Fungal sprays in a Building to Address Bacteria or Mold?

Guide to Using Biocides, Fungal Sprays, Mold Sprays, Sanitizers, Sealants for Indoor Mold, Particle, or Odor Contaminants

Mold on framing in a crawl space (C) Daniel Friedman

What are the Proper Steps for Removing Indoor Mold Contamination?

Is there evidence of mold or bacterial contamination in the building such as areas of wood, paper, or other material covered with mold or mold-suspect material or signs of a prior sewer backup?

If the building has more than 30 sq.ft. of contiguous toxic or allergenic mold it should be cleaned by a professional mold remediation company. See MOLD / ENVIRONMENTAL EXPERT, HIRE ? and DO IT YOURSELF MOLD CLEANUP.

Beware: often the most serious mold we find in buildings is not the "toxic black mold" you see on a building surface, but rather the mold you don't see in building cavities, even on indoor building surfaces, or in fiberglass insulation in a damp or wet area.

See MOLD in BUILDINGS and Mold in Fiberglass Insulation for details.

Spraying a biocide at a mold remediation project (C) Daniel Friedman
  1. First properly inspect the building to confirm that a mold problem is the source of occupant complaints, accurately locate the mold reservoir, and accurately identify and correct its cause before launching any costly mold remediation job. See Premature or Inaccurate Mold Spray Application below
  2. Second it is important to physically remove contaminated or moldy materials and debris or materials and debris that have been contaminated with sewage or flood water sludge and mud.
  3. Third it is important to physically clean the contaminated surfaces in a crawl space such as moldy joists or subflooring.
  4. Fourth, use of a biocide, sanitizer, disinfectant, or surface encapsulating spray as a final step makes people feel more confident about the mold or sewage cleanup, but although this is a widespread practice, the use of biocides is questioned by experts.
    See Recommendation Against Biocides [for mold remediation] below.

    One could certainly question the usefulness, effectiveness, and wisdom of spraying carpeting such as shown in our page top photo. If the carpeting is so infected as to "need" spraying with a disinfectant, it and its padding should be removed, discarded, and the surfaces cleaned instead.

Sources of Disinfectants, Sanitizers & Sealants for Use in Buildings

At DISINFECTANTS & SANITIZERS, SOURCES we provide a complete product list and we give contact information for suppliers of biocides, cleaners, fungicidal sealants, sanitizers, paints including the examples that are listed just below.

Be Careful to Avoid Premature or Inaccurate Mold Spray Application

Client pointing to area where applicator sprayed CalBrite (C) Daniel Friedman

At a follow-up investigation requested by homeowners (client Z., 2007) we learned that a local mold remediator had applied a spray product into wall cavities and on interior wall surfaces.The clients reported that a "biocidal spray" was used in their basement and in upper floor wall cavities. (See Biocide Sanitizer Confusion below).

Because the problem mold reservoir had not been properly located, moldy odors and mold complaints persisted in the home.

The client is shown (photo at left) indicating one of the basement spray application locations. Based on client-perceived odor sources, the remediator used an thermography - an infra-red camera to identify cool areas around a window, areas that he then identified to the client as the problem mold reservoir. A mold spray product was applied through small openings into wall cavities around the window and on exposed surfaces in other building locations. (Photo, left).

THERMOGRAPHY IR Infra Red & Thermal Scanners - discusses use of infrared and thermography images and temperature scanning equipment.

The source of odors in a building can be tricky to pinpoint, as we discuss at ODORS GASES SMELLS, DIAGNOSIS & CURE.

When the client continued to complain of mold odors in the home, a subsequent inspection including test cuts by the author were made into the previously-sprayed wall cavity where we found evidence that no water or air leaks (an expected cause of mold in a building cavity) nor mold had previously been present where the spray was applied.

That inspection and subsequent laboratory testing indicated that the spray procedure had been ineffective, almost certainly because it was applied based on poor mold-locating methodology, and because it had not been applied where mold was in fact present in a problem mold reservoir that we located (by inspection) elsewhere in the building.

The client's leftover product's package label described the coating as intended for ceilings, roofs, decks, walls, mold, odor, and exterior surface cleaning, and USDA authorized for use in federally inspected meat and poultry plants. The "left over material" was labeled as CalBrite™. The company's attorneys have indicated that:

"CalBrite is not held out to be a biocide. To the contrary, CalBrite is a sanitizer, and when used it will kill as much mold as a more chemically potent or harmful biocide."

At its core however, the ultimate success of this mold odor removal case turned not on choice of mold spray chemical, but on accurately finding the problem mold reservoir. It illustrates the importance of determining that a problem mold reservoir is present in a building, using valid investigation and testing methods, and accurately locating the problem(s) in the building before any costly cleaning, sprays or other steps are applied.

See MOLD CLEANUP - MISTAKES to AVOID for a master list of the principal ways that people foul up mold cleanup projects.


Biocide - Sanitizer Definitions & Confusion Among Biocide, Disinfectant, Sanitizer, Sterilizer

It appears that many consumers and perhaps some mold remediators are unclear about the distinction among definitions of biocide, disinfectant, sanitizer, and sterilizer. [Given just below.] While the producers of various cleaning products are careful to distinguish among these terms when describing their individual products, a search for official definitions shows why confusion might be expected among the general public. Even U.S. EPA mixes and merges these terms and often discusses them together.

"The cleanup process involves thorough washing and disinfecting of the walls, floors, closets, shelves, and contents of the house. In most cases, common household cleaning products and disinfectants are used for this task. ... It is important to remember that disinfectants and sanitizers contain toxic substances. The ability of chemicals in cleaning products to cause health effects varies greatly, from those with no known health effects to those that are highly toxic."

"... sanitizer products, as defined in section 455.10, are "pesticide products that are intended to disinfect or sanitize, reducing or mitigating growth or development of microbiological organisms including bacteria, fungi, or viruses on inanimate surfaces in the household, institutional, and/or commercial environment and whose labeled directions for use result in the product being discharged to ... [potable water supplies]" -- U.S. EPA

New York State's health department describes bleach as a sanitizer.

Basic Definitions of Biocide, Disinfect, Sterilize, Sanitize, Sanitizer

An example of a biocide product is Bio-Cide International's Pro-Oxine. More on biocides and an expert's recommendation against their use in mold remediation projects is provided at Recommendation Against Biocides.

Industry and product definitions of sanitizers emphasize what the producers state are less-toxic or even non-toxic (to humans and other animals) chemicals used in those products.

Our research found that a main distinction between a sanitizer and a disinfectant is that at the "specified use" dilution, the disinfectant will have a higher kill rate of bacterial pathogens than a sanitizer. As Burge points out below, some microorganisms are quite resistant to disinfectants / biocides.

Similarly, a narrow distinction between sterilize and disinfect is to distinguish between removing all living microorganisms and removing virtually all microorganisms.

See ASTM E197105 and see CSPA Public School Cleaning Product Guidelines. Also see "Basic Elements of Equipment Cleaning and Sanitizing in Food Processing and Handling Operations", University of Florida IFAS Extension.

In addition to the use of biocides or sanitizers directly in or on buildings, some building coatings may contain a biocide or a sanitizer product as well.

Recommendations Against Use of Biocides in Buildings?

Really? Some experts also warn that at least some biocides may be irritating or harmful to building occupants, may leave harmful particles, are only temporarily and only partly effective, and may add moisture that adds problems to the building to the question “When should I use biocides during fungal remediation in buildings?” the short answer is that use of biocides should be avoided if you can.

We agree with the following opinion expressed by Dr. Harriet Burge, our favorite teacher and a respected expert in the field of public health:

Biocides, as the word indicates, are designed to kill living organisms. The simplest answer to the question, is to use biocides when you want to kill something. Answers are never so simplistic, however. Before using a biocide, you should consider the following questions:

  1. Is killing the organism going to make a difference in the remediation outcome? The answer to the first question, at least with respect to fungal growth in buildings, is usually “no”. Most illnesses and symptoms related to fungal exposure will occur whether or not the fungus is alive or dead.

    Also, the use of biocides will only marginally change the speed with which re-growth occurs if suitable moisture conditions recur. Cases where biocides may affect outcomes are in hospitals where infection of immunocompromised patients is of concern, in cleaning up bird droppings infested with Cryptococcus neoformans, or as a delay tactic in areas prone to repeated wetting.

    Fixing the water problem, or using materials that do not support fungal growth, are better long-term solutions.
    See MOLD KILLING GUIDE for more about "killing" mold.
  2. Is the biocide effective against the organisms of concern in this case? The second question is equally important, especially for fungi. Most biocides were designed to kill infectious bacteria in hospitals and other high-risk environments. Many biocides that work well against bacteria are essentially useless for the control of fungi.

    Thus, fungi are highly resistant to ozone, ultraviolet radiation, quarternary ammonium compounds, and many other commonly used biocides. Some of these biocides (e.g., ozone) will inactivate some spores in a population and enhance germination for those remaining. For this reason, reliance on biocides is not recommended for the control of most fungi.

    Examples of biocides that are effective against fungi are: ethylene oxide (useful as a fumigant for wet, moldy books), formaldehyde in high concentrations, and glutaraldehyde in high concentrations. None of these are recommended for use except under exceptional circumstances due to their potential toxicity.
  3. Is exposure to the biocide more or less dangerous than exposure to the living agent(s) of concern? For any biocide, it is important to weigh the risks of human exposure to the biocide against the potential benefit of reducing human exposure to the fungal species targeted.

    For many infectious disease agents for which most biocides were designed, the disease is far worse than exposure to the biocide. So the answer is, for nonspecific building-related symptoms, the risk tradeoff is not so clear-cut.

If possible, biocide use should be avoided. If there is a logical reason to use biocides in a specific case, then care must be taken to insure that the biocide will be effective and that human exposure to the biocide will be minimized. -- Dr. Harriet Burge EM Lab by email 8/30/04

Also see MOLD CLEANUP - MISTAKES to AVOID for a master list of the principal ways that people foul up mold cleanup projects.

When is it Good Practice to use Disinfectants, Biocides, Mold Paints, Fungicidal Sealants and Encapsulant Sprays in a Crawl Space or in Other Building Areas?

Use a disinfectant when it is necessary to - as Burge said - kill something. For example when cleaning up a building sewage spill it is necessary to first wash, then disinfect surfaces and contents. Details about these procedures are at

Clear Fosters 4051 encapsulant spray (C) Daniel Friedman

Surface encapsulant sprays are used by mold and flood damage remediators to knock down remaining airborne particles in the work area and to immobilize (the hopefully very few) particles that remain on surfaces and in crevices of a building area after professional cleaning.

Encapsulant mold spray on top of thick debris (C) Daniel Friedman

We sometimes see encapsulant sprays applied right on top of thick heavy debris or on building insulation. This is an ineffective shortcut that should be avoided. (Photo at above left).

Our laboratory photo shows how a clear encapsulant spray (Fosters 4051™) produced individual "over spray" dried droplets which captured both small particles and some large fiberglass insulation fragments that were airborne at the time the encapsulant was being sprayed in the remediation area.

Fosters 4051 encapsulated particles (C) Daniel Friedman

Clean, don't just spray: Do not, however, permit the use of biocides, disinfectants, sprays, or encapsulants as a substitute for the physical cleaning that must come first.

Sloppy mold spray application (C) Daniel Friedman

Otherwise there is risk that you will leave harmful contaminants and particles in the building, and it is likely that cleanup will be inadequate. Look at the thick debris sprayed-over in this building. Simply stirring the debris shows that this approach was ineffective.

If you are going to apply a mold paint or sealant in a building, be neat and thorough. Don't accept an incomplete, amateur job like the one shown in our photo at left.

Fiberlok IAQ 6000 HD™, Anabec X70™ waterborne sealant, and Fosters 4051™ (clear coating shown at above right) produce sealants frequently used by mold and flood damage remediation companies.

Also see Protex™ 63, a sealant and coating t formulated for exterior use. Or see our complete list at DISINFECTANTS & SANITIZERS, SOURCES.

Once the building has been cleaned of debris and moldy materials, and building leaks, moisture traps, or crawl space water has removed, and after we've eliminated the sources of building water entry, we are ready to take the next steps to keep the building clean and dry. ( MOLD PREVENTION GUIDE)

Also see see TRAPPED MOLD BETWEEN WOOD SURFACES for a discussion of the question of need to remove mold from mated and inaccessible building surfaces.

Readers should also see CRAWL SPACE DRYOUT - home if your building is built over a crawl area

Mold Cleanup Articles


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