Mold Control on a Budget


Question: What would you want to know if you were interviewing

representatives of mold removal services?

May: Here's my list.

Would the mold removal service work with me and use the products I want used?

I wouldn't want to replace mold contamination with chemical fumes from pesticides in cleaning or encapsulation products. That doesn't make any sense to me. I would only be comfortable with a lime-based encapsulant, such as Caliwel or whitewash, depending on my comfort level and pocketbook.

Caliwel is EPA-registered for use in mold remediation, but whitewash is not. The remediation company may understandably insist on an EPA-registered product. (I have no financial interest in Caliwel.)

For cleaning, I would want Borax solution used. (A US Borax company representative may tell you it's not for cleaning mold, but I've seen its effectiveness under the microscope.) I find Borax solution far more effective than chlorinated bleach for cleaning mold off a surface. To me, folk who still work with chlorinated bleach solution do not monitor their work with a microscope.

Under the microscope, I have seen before-and-after cleaning samples comparing chlorinated bleach, hydrogen peroxide, other conventional cleaning products, and Borax. Borax easily wins the contest for an effective, least-toxic cleaning product. Borax is excellent, the rest tested mediocre.

Question: The remediator I interviewed says he'll use a biocide for cleaning.

Response: A biocide kills mold, but what kills mold might also harm us. Why bring on the big guns when Borax will do? You don't have to kill the mold. Just get rid of it.

Is the representative willing to put my requirements in writing?

How can I be assured that this information will be communicated to the project manager and from that person, to the workers? If you have it in writing, you have something to fall back on if needed.

Question: "Is there a conflict of interest with a remediation company performing both mold removal and mold testing?"

Such a conflict of interest is not permitted in the lead and asbestos industries, and states such as Florida are passing legislation to outlaw such a conflict of interest in the mold industry.

Nevertheless, if you look in the Yellow Pages, you will most likely find ads for companies offering both inspection and remediation services.

I would want an independent investigator whom I could trust to be my advocate, preferably one with a microscope.

The Standard of Ethics of our national professional organization, the Indoor Air Quality Association,, forbids a conflict of interest whereby a mold remediation company also offers mold inspection services.

Imagine this scenario: "We'll give you a free mold inspection. And then, if there is mold, we  will do the mold removal for you." Since mold is everywhere, I wouldn't trust such a company to put a proper context to their test results.

I'd also be concerned if the company worked with "green" products, because most of the green products I've crossed paths with have not stood the test of time. Mold grows back.

I'm in favor of least-toxic green products, but not all green products are least-toxic or effective. I want green products that are also effective and stand the test of time. The only product I'm currently recommending is Borax solution for cleaning. Caliwel (or whitewash) is recommended for encapsulation, because neither contains chemical pesticides (other than lime).

I'd ask if the company representative is comfortable with me bringing in my own post-remediation mold inspector prior to encapsulation.

To put this into simple terms, I want to make sure they don't paint over mold. If I'm hiring them to clean the surface, I want the surface clean and even invisible mold gone.

How do you confirm that invisible mold is gone from a surface? There are two ways: either with an inspector who works with a microscope, or send a sample or two to a microbiology laboratory.

One exception to this is if I am pretty sure that there are only moderate levels of mold on the surface, I might be comfortable with them vacuuming the surface and then just painting over with Caliwel, which kills mold on contact.

Watch out for piglet mold remediators.

At one mold remediation course I took for professional enrichment, the instructor spoke about fees. He asked how much profit is enough. "If your expenses are $5,000 for a job, would a $10,000 fee be reasonable?" He knew there are remediators going for $20,000 or more.
You'd never pay such a high hourly rate if they broke down the project into hours. It's more lucrative for them to charge you a flat fee for the project, or to include a lot of extra charges.

On the other hand, expenses for a professional remediation company can be high, such as for insurance, training and certifications, and paying decent salaries to hold onto good help. You'll have to make a judgment call in this area. Some companies, for example, might include the use of negative air machines and air scrubbers in their fees, but others would charge extra for rental.

Remember, the objective of the company representative is to charm you and sell the job. But the job is only as good as the workers they send.

Agree on post-remediation standards.

That is, what type of testing will be done following the remediation work? How will a determination be made as to whether the job is acceptable or not? If the job is judged to need additional work, is there any guarantee that the company will provide this additional work at no extra charge? In my experience, companies more often than not agree to do additional work but want to charge for it.

Here are my post-remediation standards:

  • Work with a microscope to confirm that mold growth is gone from surfaces. Removal of growth is my main concern. Numbers of stray spores can always be reduced later with routine HEPA vacuuming and damp dusting.
  • Take a few spore trap samples for independent laboratory analysis. I like to see raw count numbers, particularly of Aspergillus and
    Penicillium, down in the single digits, but if they are reasonably low, I know that routine HEPA vacuuming and damp dusting will continue to remove stray spores from circulation.
  • Possibly do some culture plate sampling, depending on the job.

Would I be interested in references?

Not that much. I have a hunch that it's not too hard to pass a spore trap air quality test after the work is done. One remediation company owner proudly told me, "We've never failed a post-remediation testing," with the mold inspector they used for post-remediation testing. My (silent) thought was that the inspector didn't know where to look.

Perhaps that's being unfair. I generally don't "fail" a job, either - except sometimes where the company hasn't followed my instructions - but often there are "touch-ups" that are needed. Maybe additional demolition is required, or encapsulation. This is not "failure," because the remediation workers are doing their best to clean something that is invisible. My job, with the microscope, is to give them guidance about any remaining invisible mold. It's in everybody's best interests that we work together to get rid of all the mold.

Caliwel is always a secret weapon, too. If you wonder whether mold residue is growing on a surface, coat the surface with two coats of Caliwel. If mold was there, it will be killed and the surface sealed.

Two limitations with Caliwel:

  • One client used it on drywall in a below-grade room. When she went to paint color over it, the finish was splotchy. I think that, unless maybe I was using white paint, I'd avoid Caliwel on a wall that was going to be painted over. Put two coats on the paper backing of drywall, though, to protect that surface.
    Note: Alistagen has recently come out with a Caliwel paint, so check with them regarding the application that interests you.
  • One chemically sensitive client reacted to the slight odor of Caliwel. After a few weeks, when the Caliwel thoroughly cured, she had no problem with it. The mild odor diminishes quickly after the product dries. According to the manufacturer, Caliwel contains no VOCs (volatile organic compounds).

I'm not particularly interested in how experienced the company is.

To me, a less experienced company might be more open to listening to instructions. My instructions often differ from the usual way a mold remediation company conducts business, particularly in the products used.

My best experience on a large residential mold removal job was where the crew was ignorant about mold. My clients opted to work with their construction contractor who had never done a mold removal job. The contractor's workers had humility and listened to what I told them.

We got to the end of the project with laughter and hard work, and the job was done just the way I instructed. The contractor rented an air scrubber for the project. The total cost to the clients was $20,000, compared to $80,000 estimated by several mold remediation companies.

Today the remediation cost would be even less, because I didn't know about Caliwel at the time of that project. Caliwel would have enabled the crew to cut out a lot of scrubbing and would have eliminated a lot of microscope work for me, too.

We just didn't have the tools we needed when mold hit the headlines. I was still using hydrogen peroxide as a cleaning product, but it was mediocre compared to Borax, which I found later. Hydrogen peroxide was no better than chlorinated bleach, but at least the workers weren't breathing in chlorine, which is a suspected carcinogen and can give off carcinogenic by-products in contact with wood.

We also didn't have an encapsulation product that didn't have a chemical mildewcide in it - even the green products I found had "optional" mildewcides. Every time I ordered a gallon to test without the mildewcide, the order always seemed to arrive with the optional chemical pesticide in it. I began to understand that the manufacturer knew the green product wouldn't be effective without the chemical pesticide - so what was the point of using this green product?

As you can imagine, I was delighted to find Caliwel, a lime-based product that kills mold on contact. At last I had an encapsulant that wasn't going to off-gas chemical pesticides. I don't know of any competitor to Caliwel, not at this time.

There is some question whether treating a surface with BoraCare or Timbor (termite-treating green products based on Borax/boric acid) is effective for killing mold and protecting the surface for the long haul, but these products are not registered with the EPA for use in mold remediation and I am not experienced with them. If the price is the same for Caliwel and that IS registered, I figure, "Why look elsewhere?"


Whitewash is made of lime, which is calcium hydroxide. Calcium hydroxide eventually breaks down into calcium carbonate, which I presume would not be effective against mold. How long this process takes, I have no idea.

The process discovered by the Alistagen folk in the manufacturer of Caliwel slows down this process of calcium hydroxide changing to calcium carbonate, as I understand it.

On the other hand, I saw what was probably whitewash applied a hundred years ago or so in the basement of an old house. In a relatively dry basement, I usually find very little mold on the old wood anyway. However, here, there was a little mold on bare wood and none noted on the whitewashed surfaces. I just tucked this experience away in my mind. It's not enough to draw any firm conclusions on. When the opportunity presents itself, I need to experiment with whitewash.

A colleague who works for the health department in South Africa and I have brain-stormed on what might work to control mold in the huts of poverty-level folk. I know of nothing more promising and affordable than Borax and whitewash.

Stories of unhappy mold removal experiences:

The contractor probably didn't know that the products he was using weren't effective, because nobody ever checked the job just a few weeks later.

Two clients worked with a mold remediation contractor who came with wonderful references and promised a lot. However, the contractor used green products, and the products didn't pass the test of time (mold grew back within two weeks). At first the contractor responded, and said he would do what the clients wanted to make them happy -- only it would cost them additional...because HIS product failed. When they objected, he stopped answering the phone.

This contractor didn't adequately research his product to see if it would be safe to use with a chemically sensitive person.

One man hired a local mold remediation company and told representatives that he wanted only safe products used in his house, because he was chemically sensitive. The representative told him not to worry, that the products they used were benign.

The man proved to be so sensitive to the conventional products that he ended up having to knock down his house and re-build. He sued the company, but the suit is still pending.

Please note that some mold remediation companies have customers sign off that they are not responsible if someone reacts adversely to a product used in the home. Such a written release was advised at the course I took in mold remediation.

Homeowners might consider doing a test-run with a product for personal sensitivities prior to it being used in their house. Painting a piece of spare lumber with the product and seeing what it smells like after it dries may rule out a troublesome product.

The project manager did not share my report with the workers.

A woman hired a mold remediation company to clean the mold in her basement. My report stated that the worst areas of mold were the ceiling joists and subflooring, but the project manager forgot to mention that to the workers. They cleaned up everything except for the ceiling, which looked fine but in actuality was covered with Aspergillus.

When I did the post-remediation testing, I checked the ceiling by taking tape samples and looking at them under my microscope. I saw as much invisible mold at the ceiling as there was before the remediation. The project manager was cooperative and sent a crew back to clean and encapsulate the ceiling. The woman would never have known about the remaining mold without a post-remediation check with a microscope.

Take-home lesson: How do you ensure that what you agreed upon with the project manager gets conveyed to the workers? This is not a simple issue, particularly since the work area typically is off-limits to the homeowners and since workers often do not speak English.

As I occasionally joked, "Bring in the cleaning women!"

One woman was so distressed with the quality of demolition work done by her mold removal crew that she expressed her hope to the project manager that they do a better job with the cleaning end of the project.

The project manager replied, "Not to worry. We have a crew of Russian cleaning women coming in for that, and you'll be happy with them."

Take-home lesson: Cleaning up mold is a careful, meticulous cleaning job, followed by capturing settled stray spores from flooring and horizontal surfaces by HEPA vacuuming and damp dusting. Let spores settle down first over 4-8 hours. Repeat vacuuming and dusting a few times, with 8 hours or more between sessions.

Mold spores were "blasted" throughout the house.

A mold removal company representative assured the homeowners that soda blasting (high-pressure blasting of baking soda on moldy surfaces to dislodge mold spores)  would clean the surfaces. I later found that mold spores had been blasted throughout the house. Some companies use dry ice blasting, but doing this would be as tricky as using baking soda.

The client got a surprise bill.

My client did not want an open estimate. She asked for - and received - a "not-to-exceed" figure. Yet, later the project manager insisted that more money was owed because he believed that work extended beyond what was in my report. The "hints" he gave on a couple of occasions passed right over her head and mine, because we both thought there was a cap to the project. She had a "not-to-exceed" figure in writing in the contract, and thought it meant what it said.

The situation became more and more unhappy. My client and the remediation company eventually came to a compromise above the "not-to-exceed" figure, just to avoid a lien against the property. Her attorney said she'd win in court, but she'd end up losing with attorney fees. I forfeited my fee to her because I had recommended the remediation company. I'm not totally sure what the lesson is, I do know it was expensive. Maybe you'll be smarter for our experience.

Sorry about what the reference books say.

The basement ceiling was wiped down with a product that any mold remediation reference book says kills mold. To me, there was as much mold left after the wipe down as I observed under the microscope prior to cleaning.

If roots aren't encapsulated - surprise - they grow back.

At one house, a mold remediation project manager refused to encapsulate the kitchen ceiling joists and subflooring after cleaning. He said it wasn't necessary. A month later, Aspergillus mold covered the ceiling joists and subflooring, and they had to re-clean it. This time, the ceiling was encapsulated.

Thinking outside the box.

At many jobs, the remediation company builds a temporary plastic room around the work area (called "containment"). If you walk into that enclosure you feel like you're in a plastic box. It's not so hard to clean up mold inside a plastic box -- but does that mean that there's no mold outside the box, too?

I understand that the company wants to limit the scope of the job -- but as a homeowner, I would like to know that not just one area of mold has been dealt with. I'd like an in-depth mold investigation prior to contracting for mold removal. I'd want a protocol drawn up that addresses mold in my home, not just in one small area.

The mold industry addresses this by saying they need to restore an area to the pre-incident state. In other words, they are responsible just for the area of the recent leak or whatever brings them to the house.

I guess the company would have to draw the line somewhere, but I like to discuss with the homeowners the testing options. I figure if someone is interested in mold from a leak, they'd also like to know if another area of the house has mold, too. Why spend money to fix one area, when spores and fumes from another area might be essentially voiding the investment the homeowners have made in mold remediation? But then, my approach is holistic.

Testing the mold remediator's equipment?

I often wonder if the spore trap testing typically performed after a mold remediation job is mainly testing the efficiency of the air scrubber or negative air machine. Maybe if no mold cleaning were done other than running an air scrubber for a week prior to testing, the area would also test clean.

Spore trap testing draws in a given amount of air, and the lab technician counts the stray spores from that air.

Maybe the area passes the post-remediation test, but there's still a lot of mold on one or more surfaces. A day after cleaning, chances are good that the air is still clean. But what about a week later, or a month later? Will the air still be clean? From the standpoint of the mold remediation company, they think, "How do I know what the homeowner might do in the interim if we wait longer for post-remediation testing? The homeowner might open windows, and spores would blow in. My job might fail the post-remediation test, and I'd be in a mess not of my making."

One mold removal company owner told me, "I'm responsible that the job passes the post-remediation testing on the day after I finish work. After that, I don't know what happens, and I'm not responsible."

This is another reason I like to work with the microscope to check surfaces after mold removal and cleaning. If I find an area that still has significant mold growth, I want the mold remediation company to return and attend to that area. My in-depth work protects everyone. It protects the health of the family. It protects the back of the mold remediator, who runs less risk of being sued.

The problem: Almost no mold inspectors work with a microscope. At the least, you can work with me through the mail with tape samples. See the Mold Testing section.

Blame the homeowner for not controlling the relative humidity.

Mold grew back to the point of being visible a year later in a basement. The company had not applied an encapsulant to wood surfaces, contrary to what I had recommended. Rather than accept responsibility that they didn't follow instructions, they blamed the homeowners for not controlling relative humidity. (If Caliwel had been applied, controlling relative humidity becomes much less significant.)

A franchise mold remediation company was hired to clean off the ceiling joists and subflooring in a basement. They said that they had to use their franchise cleaning solutions. OK, no choice.

But, twice the remediation crew cleaned, and twice I found unacceptable levels of Aspergillus remaining on the ceiling joists and subflooring. Finally they agreed to use Borax - but, when I returned, I still found high levels of Aspergillus.  I knew Borax would work. What did the crew do wrong?? The franchise company representative got fed up with me and refused to send any workers back.

Even though the builder was supposed to pay the bill for re-cleaning, the builder went bankrupt. My clients were initially told that they had to "sign off" at the start of the project giving permission for mold workers to be in their house. The clients learned only later that what they had "signed off" on was to agree to pay the bill if the builder defaulted.

The clients found another local mold remediation company who came in, used the Borax solution as directed, and removed the mold from the ceilings joists and subflooring on the first try - for $500, I might add. The homeowners were delighted -- though they later had to come to a settlement with the original company that couldn't seem to get mold off the basement ceiling.

I wonder how many jobs are left with mold growth that nobody knows is there, because no one works with an on-site microscope?

If I were you, I'd slap two coats of Caliwel on every square inch of wood in a below-grade space, unless you live in a desert. Or, on the budget plan, paint on whitewash, though I don't know what the track record for whitewash is. Caliwel's is at least 10 years. None of the remediation products that I know of guarantee a lifetime. The only product that did that was the old leaded enamel paint - great stuff. Mold would never grow on it. Too bad it was poison.

Top of page

Tell a Friend

EnviroHealth Consulting, Inc., 1-888-735-9649

Mold and other environmental inspections available in

  Connecticut - Maryland - New Jersey - New York - Pennsylvania - Virginia - Washington DC and other areas

Updated 9-2011