How to control Mold Part 1
Identifying and Controlling Mold
Molds are some of the oldest known living organisms. Molds fall into the phylum of fungi. Animals consume organic matter and oxygen to produce food. Plants absorb mineral matter and convert it to food by using light through the process of photosynthesis. Fungi do neither of these. They do consume organic matter, but process it by excreting chemical compounds to breakdown the material into proteins that can be absorbed as food. While most molds do require a certain amount of oxygen, it does not support their digestive needs and they are not oxygen dependant in the same way plants and animals are. While fungi as a class of organisms vary widely in type, I will deal more specifically with molds likely to be found in buildings. Common molds require 3 things to thrive. 1. Temperatures in the range of 40-110 degrees Fahrenheit. 2. An organic food source. From wood, paper, leather, dead skin cells, soap scum, to leaves and even other molds. Some molds are parasitic and will thrive on their brethren. 3. Molds require moisture in range of 60% sustained relative humidity or .6 water content. Take away any of these 3 things and molds cannot thrive. Molds can be of a variety of colors. Often the color is dictated by the food source, but can be a method to classify the species.
Molds produce a variety of chemical compounds as part of their life cycle known as mycotoxins. These can be some of the nastiest chemicals imagined. (These are what make some mushrooms deadly). Fortunately, they are produced in extremely small quantities. Fact: bread molds produce some of the nastiest chemicals. Molds use these chemicals to 1. Breakdown organic materials for absorption as food. 2. Defense against other organisms. Molds can alter the chemical production based on the food source or environmental conditions. It is these chemicals that you are sensing when something smells “musty or moldy”. It is a fact that the chemicals produced by molds and the proteins which make up molds can be allergenic. Some people are more susceptible than others. One person’s reaction to molds may be completely different than the next. The mold type greatly determines toxicity. For example, the fungus Histoplasma capsulatum is the cause of the disease histoplasmosis and is very dangerous, even deadly. Fortunately it is not associated with common molds. Typical reactions to common household molds are runny nose, itchy eyes and sneezing. Persons with other health issues can have a much worse reaction when exposed to molds. The very young, the very old, people with compromised immune systems, those with pulmonary diseases like asthma and those undergoing cancer treatment should avoid exposure. The toxicity of common household molds is generally misunderstood and has been unfortunately hyped by the media. Stachybotrys or “black mold” is lately being identified as “deadly” by some sources, but little true scientific evidence exists to justify it’s “deadly” description.
How to get mold:
Molds spread by way of spores. Basically, these are microscopic “seeds” They are found everywhere on the face of the earth. They have been found in ice cores thousands of years old and in the deserts hundreds of miles from any source. The last breath you took included at least several. Sprinkle ranch dressing on your salad and you ingested several thousand. ( I once saw an air clearance sample ruined by a worker sprinkling dressing on his salad for lunch near an air sampling pump) It is practically impossible to eliminate spores from the airstream. If a spore lands on a surface where an organic food source is present along with sufficient moisture it will “germinate”. It will begin to produce hyphae (the fuzzy stuff). Some hyphae will penetrate porous surfaces as mycellium. As it matures the mass becomes known as a colony and will produce spores. If the moisture is removed, the colony will wither. Spore production will cease and the colony will go dormant. It will not die, but will lie in a dormant condition until moisture levels return to allow it to once again thrive.
Now that I’ve got it………………..
OH MY GOD, I’VE GOT MOLD!! That seems to be the first reaction of many. First words of advice: Don’t panic. You’ve had mold all along. You just didn’t know it. I have yet to see a house that didn’t have mold somewhere. If you know where to look, you’ll find it, even in a new house, and even in one that looks perfect. Trust me. It’s there.
ADVICE FROM HERE ON IS MEANT FOR DIY PURPOSES. YOU and YOU ALONE have to determine what you are comfortable doing. How safe you and anyone living with you will be is strictly your call. If you have misgivings about working near mold, then absolutely call a professional remediation company. Certain areas have limits on how much remediation can be done without licensing (usually determined by square footage). I know of none that extend those limits to the homeowner doing his own work.
That said, if you’ve got mold, you need to evaluate why. Mold growing in the corners of showers or on the counter under your breadbox do not require any special handling. Spray them down with a common household cleaner and move on. After all, showers = >60% humidity, warm temperatures and organic food( soap scum). However, if you are one of the many and unfortunate, you may have found it somewhere totally unexpected. Remember what mold needs to live. You likely can’t control the food source or the temperature, but you can control the moisture. Whether it’s repairing a leaky pipe or roof or correcting a ventilation problem, the very first thing is to correct the moisture issue and bring it below the comfort level for mold. Without correction of the moisture problem, all other work is for nothing.
Evaluate the surface where mold is thriving. On accumulated dust? A simple clean up with a household cleaner. On grandpa’s WW2 leather flying jacket? Bag it and take it a dry cleaner. Most porous content items are not worthy of serious attention. There are restoration specialists that can help you with the family bible, but 2 years worth of magazines just need to be trashed. Mold on building materials? Now you have to do some serious work. First, get yourself a true respirator. Not a paper dust mask. Get a respirator with an N95 rating. Make sure it has P100 filters in it. Get some safety goggles. You don’t want to be breathing any volume of this crap. I don’t care whether you think you have leather lungs or not. There is never a good time to test whether you are susceptible to mold. Set up a fan to move the air in the space directly to the outside. That will prevent migration of high concentrations of spores and mold fragments into the rest of the building. Put up some plastic sheet to segregate the area as well. Can it be cleaned? Paneling, drywall, ceiling tiles are throw aways. Most times, moisture levels high enough to grow mold, have compromised the integrity of these items anyway, so bag them and toss them. Carpet? Roll it. Wrap it in plastic and take it out. See if anyone near you can recommend a cleaning establishment. Cleaning it in place? Not usually an option. Most good carpet has a pad under it that needs to be tossed. Cheap carpet is not worth the trouble and expense, and most of it can’t be thoroughly cleaned. Wipe down any visible mold. This will save some airborne mold debris from moving around. For drywall, a moisture meter is a handy gadget. If you have one or can get one, take a reading at an area known (or assumed) to be dry. Then take readings as you approach the area suspected to be damp. As you approach the damp material, the readings will start to climb. At the first spot where they start climbing, make a mark. When you have mapped all the wet areas, connect the dots. Go 12 inches past this point and cut the wet drywall out. If it is not wet but exhibits signs of mold growth, go 12 inches past the last sign of mold. Remember what I said before about mycellia growing into porous surfaces? Now that the drywall is out of the way, look at any insulation. It’s been wet? Tear it out, bag it and toss it. It’s too cheap to mess with and it will never dry. Fiberglass itself won’t support mold growth. The problem is that it harbors organics that will. Besides, it’s pretty cheap and if it’s wet, it’s not insulating anymore.
How to control Mold Part 2
Now, if everything went well, you should be looking at some things that may not be able to be removed. This would be framing, sheathing or flooring and sub-flooring. Check these items to be sure they are salvagable. Mold remediation does not restore rotted wood. Structural parts that are rotted need to be replaced. For those that are in good condition, but have had mold growing on them, either in the past or actively, a cleaning is in order. Many people want to skip this step and go directly to treatment. The two are not the same. Use a detergent solution and a stiff nylon bristled brush to thoroughly scrub all reachable surfaces. Use a wet vac to keep after the water run off. Almost any good household cleaner will work for this. Wipe everything down and discard any rags. Allow these items to dry. If necessary, use dehumidification to speed the process. Cleaning is important to reduce the airborne load of spores and mold fragments.
Now the controversial and misunderstood part…..killing the mold. Mold is not bulletproof. Many things kill it. Some things that kill it will also kill you. OK, that is a little extreme. There are many good fungicides on the market. Some are hyped as better than others, but the good ones fall into a few categories. Phenols, Quaternary Ammonias and Sodium Hypochlorite (bleach) all kill mold. Most commercial products also include wetting agents to make them penetrate porous surfaces better. My own rule is that if the product doesn’t have an MSDS (Material Safety Data Sheet) listing it’s active ingredients, then I won’t use it. Plenty of companies tout some magic mold killer, but then hesitate to tell you what’s in them. Pass those by. Select a material to treat and follow the manufacturer’s instructions. More is not necessarily better. PARTICULARLY if you choose to use bleach. While it is effective, plain bleach should never be used in concentrations greater than 10%. There is a difference between laundry bleach and industrial bleach. Know what you are using. Bleach also needs a wetting agent to penetrate porous surfaces. Use extremely good ventilation practices, no matter what you use. Do not exceed recommendations, no matter what product you choose. Almost all fungicides are corrosive to one degree or another. No only to you, but to nails, screws wiring, etc. Respirators do not protect you from chemical fumes unless you have the right cartridges. P100s aren’t it. When treating, make certain that all surfaces have been covered. Allow this to completely dry. Hepa vac all surfaces in your contained area.
You should now have surfaces that have been scrubbed to remove the surface mold, have been treated to kill anything that was growing at least on the surface and partially below. The final step and another one that most people like to skip, is to seal the surfaces. This is done to lockdown any stray mold fragments that may still be on the surface and to minimize the emission of spores from hidden spaces that could not be reached. It also covers any stains left over. Use a stain blocker for this. Zinssers, Kilz and others will work. There are some products made specifically for mold stains and these include a certain amount of fungicide in their formulation. Not a bad idea, but not really necessary. When the sealer has dried, thoroughly clean up your work area. HEPA vac everything. Take down your plastic and bag it all. You are now ready to reconstruct.
A few extra things:
The idea here is remove and or drastically reduce the number of airborne spores, mold fragments and dead mold carcasses in your home. All of which can be allergens.
Mildew is in fact a parasitic mold that thrives on the surface of living plants. There is no mildew in your shower unless you are growing plants in there.
During work, I recommend disposable coveralls. Take them off before leaving the work area. Put on fresh ones when re-entering.
I have found that there are loads of Magic Mold Killer websites. Some are very crafty in their wording. For the uneducated they can be misleading in how they present mold and their take on how to control it. Mold is Gold, and these people are out to get your gold by selling you something that is not anymore effective than anyone else’s, and in some cases is much less.
Legionella is not mold, it is a bacteria and is treated differently than mold.
Mold does not grow on masonry. It will grow on dirt accumulated on masonry, but the PH of masonry is way out of wack to support mold.
Mold will not grow in water. Therefore it does not grow in toilets. Bacteria will grow in water. It therefore grows in toilets.
OSHA has no interest in killing mold, only in protecting workers.
The U.S. EPA is interested in protecting the environment. Their mold remediation expertise is based more on protecting the environment than killing mold. Read their advice accordingly.
When using a mold remediation company: Be sure that the company is knowledgeable about mold. Many asbestos abatement companies jumped on the mold remediation bandwagon just because the negative airflow and containment processes were similar. Remember Mold is Gold? There is a difference between removing a mineral and killing an organism. Insist on air sampling prior to starting work and the same clearance samples upon completion. These should be taken by an independent company versed in mold sampling. These should include samples taken directly in the suspect area, a sample taken indoors but away from the area and at least one outdoor sample. Compare the results. Upon completion, there should be a significant drop in airborne spores and they should be lower than the outdoor sample. Some companies will try to talk you into flat plate mold tests. Mold spores settle on to a plate loaded with gourmet mold food. Days later, after a colony has grown, they will tell you the results. While it may be fun to know what species of mold has grown, there is little useful information to be gathered from this test. You won’t know the difference between 10 colonies of penicillium and 6 colonies of aspergillus anyway.
Molds are the world’s garbage processors. Without them dead leaves would never disappear. Dead grass and organic waste would not go away and soil would not be replenished by the material that they break down. Mold remediation dates back thousands of years and is mentioned in the Old Testament.
Hope this is useful information.
Kudos on a great post.
Excellent easy to understand information. I agree on the sky is falling reaction - one thing that a lot of people down here were doing after Isaac was freaking out about mold when they should have been focusing a leetle more on the sewage issues.
Again thanks for stressing the sealing. People just tend to wipe things down with bleach etc and then they think they are done. In fact we had a so called remediation company tell us that. The bleach solution will kill the active surface mold on top of wood sheetrock etc but there is still mold in the wood. If you don't seal before you cover with sheetrock roofing etc you going to be fighting a losing battle if there is any moisture in the air.
Curious - what are you thoughts on the dry ice approach?
Thank you for the comments.
Dry ice is effective and I have used it in places where water couldn't be used. Under side of a framed roof in a really old historic house and on the floor joists in a crawl space for example. Set up is very involved. Needs a lot of containment, good air managment and supplied air respirators.
I have hundreds of homeowners that need to see this post. Thank you!
I really appreciate this post. Hopefully this will help minimizing molds on my home. :)
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