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Pre-Cleanup moldy basement framing Guide to Use of Fungicidal & Other Sealants
Used on Building Surfaces

  • POST a QUESTION or COMMENT about using mold or fungicidal sealant coatings after a mold cleanup or building flood or sewer backup

How to use mold sprays:

This article discusses the best use of fungicidal sealants and mold paints or sealants to seal remaining free dust and to retard future mold growth.

Page top photo: just spraying a sealant paint over moldy dirt and debris is an unacceptable shortcut to what should have been a more-thorough environmental cleanup job.

We discuss the pros and cons of using fungicidal sealants on wood surfaces and give sources and list types of those products.

We also discuss common errors made when cleaning wood surfaces, such as relying on bleach or performing expensive and unnecessary cleaning on cosmetic black mold on wood surfaces.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

Treat & Seal Cleaned Building Surfaces Against Future Mold, Odors, Moisture

Spraying Anabec biocide on an interior carpet (C) Daniel Friedman & AnabecAn optional step to reduce or retard future mold growth

Using a fungicidal sealant or a post-fire remediation sealant paint or coating is an extra step that can help lock-down the few remaining mold or other particles after a building clean-up operation, reduce odors, and by improving the moisture resistance of wood or drywall, reduce the chances of future mold growth.

Optionally, you may elect to treat cleaned lumber by coating its surfaces with a sealant intended for that purpose and following the recommendations of the manufacturer.

It's important to distinguish between

Watch out: Our page top photo shows fungicidal paint sprayed on demolition debris in a building. That was a poor quality job. The debris should have been removed before this sealant was applied. Neither of these sprays or treatments is a substitute for what's needed to deal with mold or other building contaminants:

  1. Find and remove the contaminant (such as mold)
  2. Clean the exposed surfaces
  3. Fix the cause of the contaminant (such as fixing leaks or an indoor moisture or humidity problem)

Just above, the worker is spraying a sanitizer or biocide onto interior carpeting in a building. If the carpet was never flooded nor mold contaminated, this spray is unnecessary.

If the carpeting was flooded by water or a sewage backup, or if it was mold contaminated, both carpet and padding should have been removed from the building and disposed of, and the exposed flooring cleaned.

Article contents

This article series explains how to clean off or remove toxic or allergenic or even just cosmetic mold found on surfaces of unfinished wooden building materials such as framing lumber (rafters, floor joists, wall studs), and building roof, wall, and floor sheathing such as plywood, tongue-and-groove pine boards, and other structural wood surfaces in buildings.

Applying Fungicidal Sealants after Mold Remediation

Photograph of sub microscopic debris and fiberglass insulation fragments encapsulated by a fungicidal sealant

The mold remediator/cleaner may elect to apply a fungicidal sealant such as Fosters™ 4020 or 4051, the Anabec™ two-step cleaner-sealer system, or non-sealant fungicides may be applied in an effort to reduce the chances of future mold growth on the cleaned surfaces.

But readers should review the advantages and warnings about using fungicides and fungicidal sealants described next.

The photograph shown here was taken in our forensic lab during examination of a mold remediation clearance dust sample.

The photo shows how a clear fungicidal encapsulant (mold sealant) can encompass and immobilize small particles, in this case fragments of fiberglass insulation and sub-micron microscopic debris which were coagulated and encapsulated into now-solidified droplets of a clear commercial mold encapsulant/sealant.

Advantages of applying a fungicidal sealant to retard future mold growth

Photograph of clear fungicidal sealant on building framing and subflooring

This photograph, taken during a mold remediation clearance inspection, shows the use of a clear fungicidal sealant applied to previously-cleaned building framing and subflooring. The shiny coating makes evident where the coating has been applied.

The transparent nature of the coating permits the inspector, building owner, or a subsequent buyer of the property to view the quality of the cleaning job. Clear encapsulants have this advantage of showing the condition of the coated surface, assuring us that the mold remediator didn't simply "spray-over" a dirty moldy surface.

On the other hand, white or pigmented fungicidal paints and sprays are easier to detect, and it's easier to see if the application missed any surfaces that were supposed to be coated.

Good mold cleanup job (C) Daniel FriedmanOur photo shows an air sampling test underway (center) in a previously-very-moldy crawl space after expert cleaning, application of a clear fungicidal sealant on wood surfaces, and installation of a secure plastic barrier over a dirt and gravel crawl space floor.

Here are some advantages of using a fungicidal sealant following mold remediation:

Warnings about using fungicidal sealants to control mold growth

Mold spray applied after cleanup (C) Daniel FriedmanOur photo shows a white fungicidal sealant paint spray coating that has been applied to all surfaces in a building basement as the last step in a mold cleanup project.

The remediator did a great job of removing moldy materials, cleaning all surfaces, and leaving no demolition dust or debris in the building - all before this mold spray paint was applied.

Mold Remediation Products, Fungicidal Sprays, Sealants, Biocides, Washes

Fungicidal, Mold, Odor, Fire-Soot Sealant Research

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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-06-26 by Sean Hodgkin - what's the effective way to clean mold from timber?

Hi. On your webpage titled MOLD CLEANUP - WOOD FRAMING & PLYWOOD you describe how mould can be removed effectively from timber by wiping off, but later on the same page, in response to a reader's question, it's stated that wiping off is an incomplete method of mould removal.

I've relied on your website for reliable and sensible advice in tackling my own mould problem, and found it a uniquely valuable resource in my attempts to remedy my own property's mould problem.

Have I misunderstood this apparent contradiction? Best regards Sean

On 2020-06-26 - by (mod) - Remove Stains Left by Surface Cleaning of Moldy Wood? Just Wiping May Not be Enough.

Bleach used to remove black stains and mold spots when restoring an old heart pine floor on Willowbrook Heights in Poughkeepsie NY(C) Daniel Friedman at InspectApedia.comYou're right, Sean, thanks for asking as that shows that I need to be more clear. Let's distinguish among

  1. Cleaning or removing mold and cosmetic repair of leftover mold-stains in wood surfaces
  2. Wiping off hard surfaces or finished surfaces vs. "wiping" porous, soft, or un-finished wood surfaces
  3. Living with harmless stains within wood that's then kept dry and clean, or sealing it for cosmetic or mold-resistance reasons

You can wipe off surface mold on any wood surface, using any household cleaner.

That is the first and most-appropriate step in removing a mold problem that is a health or IAQ concern for building occupants. For a proper repair we must also find and fix the cause of mold growth.

If the mold is on the exterior surface of finished wood or another hard surface, wiping and cleaning may be sufficient. But that may not be the case for porous wood surfaces.

That does not address the cosmetic concern about remaining mold-stains, as surface wiping can not remove mold stains that are deeper into the wood surface.

However, in my experience, the remaining, stained-wood is **only** a cosmetic issue, that is, it is harmless, not releasing mold spores into the environment, and not producing or growing more mold, ** provided ** we also dry out the area or fix leaks or high moisture - the conditions that would have caused mold growth in the past.

What remains, then, is a cosmetic issue.

In some cases, for cosmetic reasons such as on a floor or on exposed wood beams, we might want to remove more or try to remove all of that stain.

In restoring old heart pine wood flooring such as the floor shown above (3 Willowbrook Hgts Pok) I have gone so far as to swab small stain spots with a Q-tip dipped in household bleach, watched the stain lighten until it matched the surrounding wood, then cleaned off the bleach, dried the floor, and stained and re-finished that area.

You can see that one must be careful not to leave bleach on the surface for too long as well as taking care not to use a stronger bleach solution than necessary. If you do over-bleach, as I did in a couple of spots, you may be able to recover by cleaning off the bleach thoroughly and staining to match the surrounding flooring.

The more-successfully bleached spots cannot be seen at all on the flooring example I give above.

So it's possible to successfully "restore" such wood but it's labor intensive and benefits from experience and a light touch.

If the stain is deep into the wood, beyond what can be reached by media blasting

details at MOLD REMOVAL, MEDIA BLASTING

or sanding, then we're left with either complete replacement of the wood component - not usually cost-justified -

or we have to clean as much as we can and live with the stain -

or we have to give up on the exposed natural wood and instead coat the wood with a sealant or stain or even a paint.

FUNGICIDAL SPRAY & SEALANT USE GUIDE sold in either pigmented or clear forms

Really? Well, no. For leftover mold stains on wall studs in a basement whose walls are to be covered in drywall and perhaps later paneling, there is no need to remove cosmetic leftover stains once you have cleaned off surface mold and have also made sure that there are no moisture or leak sources that will invite further mold growth.

For peace of mind or "insurance" you can opt to seal the studs with a fungicidal sealant, as that reduces future moisture uptake and would retard mold growth should there be high moisture in the area later-on.

Thank you for asking; let me know if this explanation leaves you with further questions, criticism, or suggestions.

On 2020-07-04 by Sean Hodgkin - UK wood mold cleanup information - InspectApedai website has been invaluable.

Hi Daniel. Thanks very much for your response, and for clarifying the issue for me: that cleaning mould from a surface by wiping, media blasting etc, still requires the underlying cause of the mould's growth to be addressed in order for the cleaning to be effective.

I live in the UK, and there really is very little in the way of information about, or even recognition of, the problem of mould in the home here, and so to have found your website has been invaluable.
Thank you

On 2020-07-04 - by (mod) - help for UK readers with mold problems

I'm glad to assist. We value our UK readers very highly.

This Q&A and the one just below were posted originally at MOLD CLEANUP - WOOD FRAMING & PLYWOOD

Reader Question: is it OK to apply a sealer or wood preservative over black stains on plywood roof sheathing?

Last September I had a new garage roof fitted and within 7 months the plywood used inside developed black mould spots. The company that fitted the roof said it was caused by condensation.

Having wiped the roof with a mild detergent I was left with black stains on the plywood. I would like to know if it would be ok to put a wood preservative on it despite the stains - don't want it to come back.

Would appreciate your advise? - [Anon by private email 23 July 2015]

Reply:

Yes you can apply a wood preservative, leaving cosmetic black stains under the preservative.

But if you do not find and fix the cause of condensation (removing a water source and/or improving ventilation) I'd still expect future trouble.

You may find stains or mold appearing on other wood or mold-friendly surfaces in the same area if indoor moisture levels are high, or if there is building insulation present that may become mold contaminated.

See HUMIDIFIERS & HUMIDITY TARGET

See ROOF VENTILATION SPECIFICATIONS

 

Question: what fungicide would kill ringworm spores in a garage

what fungicide would kill ringworm spores in a garage - Margery, 8/26/11

Reply:

Margery, ringworm (dermatophytosis) spores can be airborne according to various experts, but my OPINION is that cleaning or removing the source is critical; trying to cure any airborne indoor air quality problem by treating the air is not likely to work - the particle source remains.

For cleaning indoor surfaces, an adequate disinfectant is needed. Vets comment that using a fairly strong Bleach solution (1:10 dilution) or lime-sulfur dip (1:33) have a LIMITED ability to inactivate ringworm spores indoors.

A vet we consulted suggested that Enilconazole, if available, can be used as disinfectant area fogger (Clinafarm SG—American Scientific Labs, Janssen Pharmaceuticals ) but

WATCH OUT, this chemical is not approved for this purpose in the US. THOROUGH cleaning of all hard surfaces is key.

I would dispose of any soft goods that can be tossed.

Some vets recommend steam cleaning carpets.

My field and lab tests of mold spores (not ringworm spores) found in and on carpets and other thick fabric materials found that it would be a rare steam device that can produce enough volume and temperature to be effective in thicker materials.

Question: How can we clean the subflooring to remove the mold before laying down the wood flooring?

We are removing laminate flooring to install wood flooring. When we removed the under pad the subflooring has mold in several places.

We do not even know how this came about. How can we clean the subflooring to remove the mold before laying down the wood flooring? Thanks. - Bill & Bonnie 10/2/11

Reply:

Bill & Bonnie, any common household cleaner, even soap and water, work fine for cleaning off mold from subflooring. Be sure the subfloor has dried before installing new materials over it. You shouldn't need to use a sealant.

Question: need to seal wood with a coating that withstands bio-hazard cleaners

I have repaired doors in a retirement facility and need to seal the exposed wood. The sealant needs to withstand bio-hazard cleaners. Any suggestions?

I am hoping you have some insight to a sealant that can be used in a medical facility that will withstand the harsh cleaners used after an out break.

Thanks,
Andy - 11/1/11

Reply:

Andy, we list a number of providers of biocides, sanitizers, and sealants in the article above and in the references at the end of this article.

It would be most effective to ask your question to those folks directly to be sure that they understand exactly your requirements.

Question: we want a non slippery penetrating sealer that goes unnoticed after it dries.

We have a travertine pool deck and stairs approximate 2000 sq ft total. Is there some products that we can use to inhibit future mold growth. The difficulty is in that we are in Naples Fl and have approximate 5 months of rain every day. We want a non slippery penetrating sealer that goes unnoticed after it dries. Kip 8/17/11

Reply:

Kip, take a look at MOLD RESISTANT CONSTRUCTION

There are fungicidal sealants and paints that can work well on some surfaces provided the surface is clean and dry and sound first.

There are some clear sealants, but I'm afraid that in native form they'd be slippery.

Talk to the manufacturer about adding an anti-slip to those paints or sealants. In other words, you may be able, with manufacturer advice, fabricate a clear sealant that includes an anti-slip additive.

Question: Have you examined the Aegis Microbe Shield technology from mPact?

Regarding your text which I quote from above --

"I have been unable to find any long term study of the enduring effect of the fungicidal or microbial effect, and some studies, such as those done on microbially-treated fiberglass duct insulation indicate that the treatment is not long-lived."

Have you examined the Aegis Microbe Shield technology from mPact?

Reply:

We have not examined nor directly tested the product you name nor performed chemical tests on any other sealant, biocide, or antimicrobial or sanitizing agent.

We do, however, review documents and technical literature about these topics and products, and we do have field and lab experience in testing buildings for mold contamination before, during, and after various approaches to mold remediation.

When evaluating the effectiveness, claims, or promises of any product it is useful to distinguish between marketing literature, "white papers" produced by the product manufacturer, and independent, peer-reviewed authoritative studies.

In some fields, such as septic tank treatments and perhaps in the area of mold treatments, these distinctions are particularly important.

Anon:

Aegis Microbe Shield is provided by mpactworldwide [dot] com. The company's description (a video) of the product is interesting and it makes a compelling argument that the product, because it does not give up any of its coating material to a microbe that lands on the treated surface, works indefinitely.

The product is described by the company as 99.9% effective against an extremely wide range of pathogens. Interestingly, the company also indicates that "Simple field-testing can quickly confirm the presence and continuing efficacy of our treatment."

"Indefinitely" is ... well, a time period of uncertain length and may not necessarily be taken to mean "forever". This helpful comment is offered by the company:

How long the technology continues to function is directly related to the life of the surface to which it is applied. In other words, while the technology may continue to fight germs indefinitely, the surface may be worn away, painted over or damaged, which would compromise the coating’s ability to function.

Assuming that the surface is kept clean and not abused, our protection will last for the life of that surface. [5]

The product is described as a proprietary formula, meaning we don't know what's in it. We did not find, among the company's download-available documents, independent, scholarly or peer-reviewed studies testing the long term durability of its surface coatings or treatments, though the company's product description is indeed quite interesting.

The company's website offers a study, examining skin absorption in rabbits, reporting on the safety of an antimicrobial that sounds like the one referred to in the company's promotional video: organosilicon quaternary ammonium chloride. [8]

Other downloads document that certain of the company's products conform with Boeing or other standards.

None of these documents discusses the questions of use of biocides in buildings, particularly as part of mold remediation, their proper use, efficacy, and long term durability.

We caution you that even if a biocide could "kill" every single mold spore (making the spores unable to germinate or grow on a surface in the future), you may be leaving toxic or allergenic particles in place. And our own field studies that sample sprayed or treated surfaces that had not first been thoroughly cleaned, often find viable as well as non-viable spores in the sample.

Finally, the best and proper mold remedy is to clean moldy surfaces, dispose of materials that cannot be effectively cleaned, and correct the leak or moisture problem that caused the mold growth. We have no objection in principle to ancillary use of biocides or other agents or cleaners to improve the process or to seal the surfaces to resist water uptake and thus retard future mold growth.

But no spray or cleaner seems to be an effective substitute for doing the real work: clean the mold and fix the leak.

Question: fighting ringworm - do I have to get rid of every spore in my home?

After fighting ringworm for three months on our dogs and one cat plus ourselves which we contacted from a rescue kitten I have come to the conclusion that constantly cleaning your whole house, basement car, garage and clothes with bleach is an impossible task which will drive anyone crazy. Easier said than done.

So if you get this scourge be prepared to live with it forever or move. You will lose all your friends and relatives with or without pets because they hear the word "ringworm "and head for the hills.

My doctor says it's no big deal unless you live in a damp dark cave but the vet thinks it's the end of the world. You can't get rid of every spore and all it takes is one to re infect you?

So what to do?If there is a hell i'm in it. - Carol Clark Hill 11/12/2012

Reply: no

Carol,

I suspect the term "spores" is misleading here - as typical airborne mold spores likely to be found in a home are not the same sort of fungal spore as the cause of ringworm or dermatophytosis. Ringworm, which can infect humans and other animals is caused by the fungus Tinea and might be spread by direct contact, not by air. More details are provided by the U.S. CDC [20]

The object of removing every single airborne or surface-dust mold spore from a building is, frankly, silly. The moment you open a door or window, spores enter from outdoors.

Once a building has been properly cleaned of a known problem reservoir, no such heroic measures are appropriate.

We understand your concern, as ringworm is an upsetting and contagious infection - when I was a kid, the animals on our farm suffered as on occasion did we. It was cured by seeing a doctor. Your doctor is right on target in my opinion. And the CDC agrees, stating

Dermatophytes can live on moist areas of the skin, on environmental surfaces, and on household items such as clothing, towels, and bedding.

and ...

Ringworm is transmitted from direct contact with an infected animal's skin or hair. [20]

Once you've cured ringworm and cleaned wet shower floors, etc, beyond normal cleaning and keeping an eye on your pets' health, take a look at our article on

HUMIDITY CONTROL & TARGETS INDOORS

for help with setting and maintaining an appropriate indoor humidity. If your vet is telling you you can get ringworm by air transmission of a fungus s/he is mistaken.

Question: hurricane Sandy flooded my sub-basement dirt floor - should I put down chemicals?

I had a flood in my sub-basement during Sandy. The sub-basement was professionally dried and cleaned.

Do I have to put some chemicals into it just to be on a safe side? The floor is dirt - Jate 11/17/2012

Reply:

Kate,

If the sub-basement was properly cleaned and dried, adding more sanitizers or chemicals should not be necessary, though there are some advantages to

- using a fungicidal sealant on exposed wood surfaces to reduce future moisture uptake

- putting down plastic over the dirt to keep moisture from migrating into the building

See these articles

for a complete list of suggestions on how to clean up & dry out a wet or flooded crawl space.

Question: hairy brown mold growing by my shower door.

(Feb 25, 2014) Emily said:
I have noticed what looks like a hairy brown mold growing by my shower door.

The shower is large, the bathroom is large and well ventilated. I suspect part of the problem was a shower mat that seems to retain water all the time.

I dismissed it, and washed some of it away with hot water thinking "I'll deal with this over the weekend." Today I step in the shower to find the brown mold has sprouted into two small 1-2" mushrooms!! There appears to be no leak when I go into the basement and look under the shower, and I'm praying it's the mat, which I've discarded.

To treat this, would a bleach-water mixture applied with a toothbrush work followed by a rinse of hot water? And would those DIY water-vinegar sprays monthly resolve this? I'd really appreciate any info!

Reply:

Emily, if you search InspectApedia for "hairy brown mold", you'll see my photos of Stemonitis sp. that you can compare to the mold you see.

It's fairly distinctive, not hazardous itself, but indicates a moisture or leak concern. When you see mushrooms growing out of a wall you can figure there is more leaking going on than you realized.

Any household cleaner approach is fine for mold cleanup and removal; bleach is nice if you are trying to correct discoloration but can be more dangerous to handle; remember that in mold cleaning the object is not to "kill" mold (which is pointless and usually ineffective) but rather to *remove* or clean off the mold and to correct the cause for its growth.


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