In this episode, Stephen will talk about one of the most common concerns homeowners and tenants have: I think I have mould in my house. Stephen will explain what mould is, how to lives and thrives and how to keep it at bay. This isn’t biology class; you will think about biting cows in a different light after this entertaining and educational exploration of mould in our homes.

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Here is the transcript for the episode:


Welcome to Your Healthy House. I’m Stephen Collette


Stephen: In this podcast, I explore your indoor environmental quality concerns and opportunities. We look at the facts and debunk the fiction. We will discuss examples you can relate to and the doable actions you can take in your own home or apartment. We will also look at the history of how our homes are, the way they are and the future of healthy housing for everyone. I promise to make this fun and interesting for you.

Stephen: Episode number three, do I have mould? As a Building Biologist I get lots of questions and people calling me with their concerns about their home and their family’s well-being. The number one statement I get from people is I think I have mould in my house. What should I do? And that’s an important question because if it is true, mould can be a very serious indoor air quality concern and mould can affect people, especially those who are sensitive. So I never want to take mould for granted. I never want to treat it casually. That said, the potential for the mould crisis being overblown is unfortunately real. And so let’s break it down together. Let’s learn about it together. Let’s try to put it in pperspective in a manner that you can understand and let’s ease those concerns and let’s help solve that problem. So first, what is mould?

Stephen: Well it’s a single celled creature, it eats starches and sugars just like you and I do, except it doesn’t get its starches and sugars from pasta or potato chips like we do. It gets its starches and sugars from cellulose chopped up trees. That’s what it really likes to eat. Now, as a single celled creature, I want you to kind of think about it like great grandma. Great grandma likes her oatmeal soft and squishy. Why does great-grandma, I like it that way because great grandma doesn’t have any teeth. Mould doesn’t have any teeth either because it’s only a single cell. So it needs its food to be soft and squishy and wet. And that is what creates the potential happy place for mold to grow. It needs food and water. It needs it to be really soft. So although mould likes to eat cellulose from trees, it can’t walk up and bite a tree any more than we would walk up and bite a cow because we want a hamburger.

Stephen: It needs to be processed in a manner that it can. Mould is almost as lazy as people. Nobody’s really that lazy. It’s going to take the path of least resistance. So the mould is going to eat dust first. It’s going to eat papers second because the lignin structure in the cellulose has already been ripped apart. It’s been torn open. So the access to the starches and sugars is a lot easier than if it was to try to chomp on a tree. And so those are always the first things. Those are kind of like the coffee drive through, right? A bag of potato chips, super easy to eat and access. So when we do get dampness in our homes, when we do get water, the dust is the first thing it’s going to eat. The second thing is going to eat paper. Then if the water can s continues long enough, it’s going to start eating a cardboard.

Stephen: And then real damage into the building materials where you’ll see your press board, baseboards, then you’ll see chipboard and then plywoods and with enough water and enough time, mold can eventually break down solid wood as well. And we do know that from experience we’ve all walked in the woods and seeing the trees and the debris altern mushrooms drawing out of it and broken down. That’s mould. Just doing its thing in its natural habitat. And outside is the natural habitat for mould. My mycologist has told me there’s over 180,000 types of mould living outside every day doing different things, doing what mould does, eating very specific segments of the world that it has found its niche. Some of those moulds do come in the house. Some of those moulds are harmful to the built environment. Some of those molds when they do come in, can eat some of our building materials, not all of them.

Stephen: Some of them just float around our home looking for some chopped grass that they prefer to eat, which we don’t have. So they are present but not a concern. But there are some moulds that live just indoors and those are the moulds we’re concerned about. They are present in our homes and some say even in our microbiomes, so it’s not sure whether the home populate our microbiome or our microbiomes populated the home’s microbiome. Kind of nerdy stuff, but interesting. All the same, but these moulds are waiting for an opportunity and that opportunity needs to come with water without the water. These moulds are just present. They’re not harming us, they’re not hurting us. They’re relatively dormant, but when we get a water event, like your hot water tank letting go or your dishwasher overflowing and things get really wet for a long time, that’s when the opportunity presents itself for a really big party and the mould knows how to party and that’s when it’s going to come in and take hold and eat the dust, eat the paper, eat what it can and populate different molds like different conditions just like we do when we eat.

Stephen: Some of us want fast food. Some of us want a slow romantic dinner, molds are the same way. When you think about mould, it’s kind of like a high school party. At six o’clock on the button the underage drinkers show up. There are gaggles of them. They’re lightweights. They can’t hold their alcohol and they’ve got like a six pack amongst 20 of them. These moulds are aspergillus and penicillium. They’re the first at the party. They’re always in most air samples I take and they’re really numerous, but they’re lightweights under the microscope. They look like pearl necklaces. They’re just little circles all in a chain. Now back to the House party. Once it’s going and things are really rocking, that’s when the house records come. This is like, you know those football guys with the big pickup truck and the Kegger, that’s when they roll in back at our house that got wet.

Stephen: This could be days later of longterm actual water’s sitting on a floor or leaking through a wall that we’re going to get the serious molds. These are going to be stachybotrus, Cladosporium. Yeah. It’s mostly Latin. You don’t need to worry about it and you don’t need to Google it. You just need to know that they’re heavier moulds. They’re physically larger moulds and so they don’t like to be aerosolized as much, so they’re usually stickier as well. Now these are the house records wreckers. Now what they’re going to do, which is really interesting, is they’re going to grab those little guys, put them in a headlock and start smashing them. That’s analogy is what they’re doing is they’re releasing mycotoxins. Their weapons of mass destruction. They’re actually trying to kill off the other moulds for the really good piece of dry wall. Now that’s interesting, but how does it affect us?

Stephen: Well, it affects us because we’re actually sensitive to those mycotoxins. Those weapons we’re actually collateral damage. The mould directly doesn’t care about us or is even aware of us obviously, but they’re just trying to fight for survival and so they release these weapons and we actually react to them. Now the little Aspergillus, the penicillium, they’re kind of used to this game after awhile, and so they bug out. So when we have a really a water damaged building, you’ll see layers and rings out the water source and in the outer edges of that rings is more where the real activities going on because down near the center, the damage is pretty severe. In some cases that that’s someone’s down in the back just chomping down, but the rest is where there’s a lot of unique molds present. Now remember I said mould is a single celled creature.

Stephen: You cannot see a single celled creature with your naked eye. If you can see some mould, whether it be on your window sills or whether it be on the fridge gaskets, or whether it be down in your basement, you’re actually seeing a lot of mold. Now, don’t freak out, but you’re actually seeing hundreds, thousands, millions of moulds because they’re individuals, single cells, you can’t see them individually, so that’s why we need to take care of it. When the water issues get out of hand, I know what’s the first thing you want to do when things get out of hand? I hear it all the time. Grab your bleach, clean the mould. Call it a day. Well remember I said there was like thousands or millions of them. When you pull out the bleach and squirt them, it’s kind of like the cops showing up at that high school party.

Stephen: Everybody scatters. Mold has an amazing text plan. It’s super cheap, super fast, and they always have five bars. You spray the bleach at one end. Remember they’re all connected. They send out a text message to everybody else that the cops have shown up at the party abandoned ship and you got kids jumping over fences and through the bushes and over the pool, and it’s chaos. What happens in the real world is mould releases spores; it’s babies. It’s bugging out and looking for a better place to party. That’s safer for it to keep it alive. So those spores are released and their mycotoxins because you are attacking them are also released; and since bleach is like super toxic because we used to drop it on the Germans in World War One and called a chlorine gas. It’s really poisonous to you too. So now I got poison gas, I got mold spores and I got mycotoxins floating around the air all while you’re supposedly trying to make things better. So please don’t use the bleach.

Stephen: It’s just making things worse. What you want to do is actually clean it with soap and water. The soap breaks a surface tension between the mould and whatever surface it is, whether it’s your window sills or your fridge seals when the water encapsulates it, so before the mould knows what’s going on, it’s been wiped off and it’s in a bucket of water mold being smarter in us, we have to trick it and soap and water. The safest thing to use. You can use dish soap, you can use trisodium phosphate; TSP, something you purchase before you paint the walls. It comes in a milk carton as crystals. It’s a great surfactant and it works really, really well, but I definitely definitely do not want you using bleach. It is really, really dangerous and it’s really unsafe. We shouldn’t be using it in our homes at all.

Stephen: If you look up the material safety data sheet for bleach, you’re supposed to wear a full rubber apron, rubber gloves, and a full face shield under a high ventilation hood. It’s not poisonous. Don’t tell me that’s how you use it at home. Cause I know that’s not true. So I get the question about the mould. What kind of mould is it? Can you tell me what kind it is? Is it the toxic kind? I think I have this kind of mould. I looked at pictures online. Again, none of that is helpful. You can’t identify mould visually. My mycologist uses a microscope to identify mould. He has degrees in this process. You can’t identify mould visually no matter what those hucksters come into the door trying to sell you air cleaners tell you. You can’t identify mould by visual. Oh, but it’s black. Nope.

Stephen: It’s just density. If you stack enough things up, it looks black. Okay. Sometimes mould is different colors. It can depend on what it eats and I can see the exact same molds on the exact same piece of drywall be different colors based on the dust that it’s starting to eat. Or the starches in the tape or from the dry wall will be different colors. So just those variations alone. So you can’t, you can’t, you can’t take color to mean anything. Really, really important. Should I test for mould? Well, if you can see it, you probably don’t need to test. Remember mould is the effect. It’s not the cause. When people call me and say I have a mould problem, I always have to correct them. You actually have a water problem. Mould is the effect. Water is the cause. Remember the three legged stool of life, food, water and a warm place.

Stephen: Now we can’t control the temperature and the food while your house is full of dust. So is mine. It’s just what it is. We’re make our homes out of mold food, unfortunately. So we can only control the water by maintaining the water and keeping water at bay within our homes. You can’t have a mould problem. It’s not possible. Manage the moisture, manage the water. You won’t have mould. But I want to test for mould. I wanna test for mould. Can’t you just come in and wave something in the air? It doesn’t work that way folks. It doesn’t. So I need to find the water. So if you think you have mould, look for water, is there a tap leak leaking? Is there a roof leaking? Do you have water coming into your basement? Is there something wet around your windows? Is the waterline to your fridge behind your fridge leaking?

Stephen: Where is the water? Find the water. If you don’t have water, you can’t have mould. And for those who live in very humid climates, which more and more of us are getting due to climate change, but if you’re in a very humid climate, we have to manage the humidity in the air because it can get so humid that we can get condensation on our surfaces and that condensation can create mould. Where do we all find that in our bathrooms? So those teenagers with their 45 minutes showers and the open the door and it’s like a sauna in there and a giant steam room. That’s definitely a place for mould growth because every single surface is sopping wet in there. It’s a hundred percent humidity and so all the dust that floats in the air sticks to all the water. The mould that’s naturally floating around in the space, in our homes, in the environment also sticks and now food, water and a warm place and that’s why you’re going to see within a bathroom that sort of mould starting to form, especially on the ceiling around the shower, around the bathtub.

Stephen: It’s always going to be that way. Managing the moisture in there with a bathroom fan with a properly installed HRV balanced, managing the materials in there that can help absorbed some of the moisture. Really, really important critical steps to reducing the potential for mould growth. Now back to what kind of testing should we test for mould? Sometimes it does make sense to test if it’s really serious, if it’s been wet long enough. Let’s use an example of a basement. If it’s been wet and mouldy in your basement long enough, there may be concerns for health issues and it may make sense to test. Why would I test? Because not that I want to know whether there’s mold in the basement. I can see it, I can see the water, you can see that there’s water damage, there’s going to be some sort of mould. But the question is is upstairs contaminated and that’s where it might make sense.

Stephen: So there are different types of mold testing and basically what I use and what most of the industry uses is not testing. So again, I want to reiterate, most professionals do not recommend testing if we know cause effect and outcomes. We can spend the money actually fixing stuff. But when testing makes sense, take an air sample in the basement, a non-viable or non culturable and more properly referred to as direct measurement. An air sample that has a microscope slide. It’s a little spore trap in the air through the air pump draws across this cassette and the air. Everything in the air sticks to that microscope slide in that cassette, like I said. Then goes to a lab who identifies it and the lab and the lab technician need to be certified that they can actually identify and understand what they’re looking at. You would also take the sample upstairs, as I said, to make sure the upstairs isn’t contaminated because that’s really serious.

Stephen: Is it safe to live there? And the third most important sample needs to be outside and that’s because most of the mold in the universe lives outside and if you’re not testing the outside air, you might be freaking out over maple tree mold or freshly cut grass mold. So really important across our potential errors. Same with multi-unit housing in a high rise you want to test out in the hallway. There are other tests out there, there is viable or culturable. Those are more accurate in a way, but they take seven to 10 days and nobody wants to wait that long. They’re really not common in the industry. They’re used for very specific things. They are a little more accurate as far as identifying the moulds, but they’re not helping anyone move forward. What I do see a lot of, unfortunately, these tests you can buy from your hardware store mold sampler test kits.

Stephen: They’re kind of like right near the radon kits and those radon kits are really useful. That’ll be another podcast episode down the road, but these mould kits are not very helpful. The reason is when I take an air sample, I have a known quantity of air that passes across the sampling medium, so I’m going to draw 75 liters of air across my spore trap cassette. That’s a known quantity. By knowing 75 liters my mycologist when looking at the sample can extrapolate how much mould is present in a cubic meter of air. Now these ones where you open them up and you leave ‘em on a countertop or something for a couple of days and then send them off to a lab, not really helpful. How much air hit it? Was there a lot of air? Was there a bunch of air? How much is a bunch? Have you ever thought about how much dust settles in your house and where the dust settles?

Stephen: You get some spots that are really dusty in some spots, not as much leaving something passive to test for air is absolutely useless. It’s not accurate, it’s not helpful, and they’re using the viable culturable and that creates a potential error because it’s alive, I want you to think about that. A medium that agar, it’s called, it’s kind of like Doritos chips. Mold loves it, but what happens is the mold that sticks to it is going to eat like crazy and one spore can completely fill the entire dish. That’s not a problem. It’s a single spore, but it looks terrible and it causes people to overreact when in fact it’s relatively clean. So there’s a lot of room for error in those. So I’d strongly recommend you don’t go near those. They’re a waste of money.

Stephen: So when we sit back and look at mould, it’s actually kind of cool. There’s really neat stuff about how it works and how it survives. Remember, some of my favorite moulds are cheese and wine. Yours too. I think so. We shouldn’t be afraid of mould. We shouldn’t let it overwhelm us and freak us out. And definitely googling can only lead to fear and unknown and and worrying by understanding basic biology, food, water, and a warm place by finding the water. Find the water first, deal with the water, then clean what’s present. Keep in mind, as long as everything’s dry, there’s nothing for the mould to drink and if there’s no drink, there’s no party. Keep your home dry. Regular Inspections nderneath your sinks, around your toilets in your basement. By keeping all that under control, mold is not something you need to be concerned about and that’s a relief. You can sleep better knowing your home is safer. Thanks for listening to this episode. I hope it was helpful. If you enjoyed it, tell your friends about it and I look forward to getting together with you on my next episode.


Stephen: enjoy this show. Please leave a review and subscribe to the podcast and you will be doing your part to help others create their own healthy homes. If you’d like to learn more about me, Stephen Collette, and what I do, please check out my website at Music for the podcast is by Brian Picket of Voodoo highway music audio technical support is by Mike Pickett. Editorial support is by Eric Rosen. I’m your host, Stephen Collette. Thanks for listening and enjoy your day. Cheers.