The following is a transcription from an audio recording. Although the transcription is largely accurate, in some cases it may be slightly incomplete or contain minor inaccuracies due to inaudible passages or transcription errors.
Bill Oelrich: Welcome everyone, you’re listening to Structure Talk, a Structure Tech presentation. My name is Bill Oelrich, alongside Tessa Murry and Reuben Saltzman, three-legged stool coming to you from the Northland, talking all things houses, home inspections and anything else that’s rattling around in our brain. Today’s guest on our episode is none other than Vickie Swenson, and Vickie is with Minnesota Mold Inspections, and we’ve invited Vickie on to the podcast today to talk about smells, odors, things that linger in people’s houses, and it’s not uncommon for Structure Tech to get requests of our inspection team to come out and try to do investigative, looking to find odors, people are like, I’ve got some funny smell, can you come out and look for this odor and help us understand this? And we usually say no, because it’s really hard to figure out why odors are happening or what the source of the odor is, or why the smell is there. So we brought Vickie on because Vickie has a fantastic nose, number one. Number two, she understands odors and houses and mold and all these other things that can cause problems, and so we thought we would pose a bunch of questions to Vickie about smells. So Vickie, how are you doing? It’s been a while since we’ve talked to you last.
Vickie Swenson: Yeah, I’m doing great, staying busy, having fun, but I’m gonna mention a little thing about my sense of smell. I had a brain tumor in 2009, completely took away my sense of smell and after this tumor was removed, it took about six months for my smell to return to normal, but now it’s a 100%, and I can walk into a house and tell you if your cat box needs cleaning, you have a fuel tank in your basement, you’re diffusing too many essential oils, I can smell it right when I walk in. So it’s very helpful, and I’m glad it returned.
Tessa Murry: Oh my gosh, I can’t imagine doing what you do without a sense of smell, Vickie.
VS: Yeah, it was really strange. I had noticed that my sense of smell was gone, but I didn’t know I had the tumor until I had a grand mal seizure in my right leg, and then I ended up in the hospital, I was in for 21 days, had a walker and a cane.
TM: Oh my gosh.
VS: So the tumor was squeezing my olfactory nerve, which might… Radiation is a possible cause I kind of wonder if it was my first career as a computer programmer sitting in front of that. Anyways, it’s gone, and my sense of smell is back and it’s such a nice thing.
TM: Wow. Oh my gosh, I’m so glad you’re here and you’re healthy. And you can smell. [chuckle]
BO: Yeah, and you just say it as a matter of fact, I had a brain tumor. What? Slow down.
VS: 13 years ago.
BO: Wow. Modern medicine is an amazing thing, isn’t it?
VS: Brain surgeons and… Very brave people. Cutting open a brain is a big deal, so.
BO: Wow, well we’re glad you’re here and sharing your knowledge with us and with a full olfactory capacity, I don’t know if that’s the right way to say it, but…
VS: Go ahead, I think it’s right.
BO: It’s… Every couple of weeks, we get a request, it seems like at the office for somebody who wants to go out and work on a smell. And it’s virtually the same response from everybody all the time. No, thank you. We will never live up to expectations, so.
Reuben Saltzman: Well… And it used to be that we’d get these requests and we’d send them out to the team, but we’ve kinda changed our stance on that and we have just drawn a hard line in the sand and said, no odors, no more, we’re done. Because they’re just… I don’t know. I feel like our success rate was going out to diagnose the cause of an odor, it’s gotta be less than 50%, and when someone’s… We charge a lot of money, we charge a lot of money for these single-item inspections, and it’s not like we can tell our inspectors, hey, you get to charge the full amount if you can figure it out, but you’re not gonna get paid if you don’t get the answer. We need to get paid either way, and it’s the most unsatisfying thing in the world to go out to somebody’s house, charge them 300 bucks, 400 bucks, whatever we charge for a single-item inspection, come out there and go, yeah, I don’t know what it is. Can I get paid now? I mean, nobody, nobody ever wants to do that, and so we just… We don’t do the odor inspections ’cause our batting average is way too low, so we’re done. You talk about odors, you gotta get to the bottom of it, call Vickie, that’s what we tell people.
BO: We should ask, Vickie, is this even something that’s part of your business model?
VS: Well, a couple of things I’m gonna say, you’re exactly right, Reuben. Odors are really hard, really hard. And you said 50%, that’s pretty good. There was an industrial hygienist who told me a decade ago that he was an odor expert and he could solve it 80% of the time, so when I tried to pick his brain, he said, well, consultants get paid for what they know, so I’m not gonna tell you, so he never really went into it.
BO: Oh my God.
RS: Oh, what?
VS: Yeah, well, I’m the opposite, I share all… We’re all in this together. We are colleagues, I consider everybody a colleague. Yeah, so I get a lot of odor calls too. In fact, in the mold business, there are really four things… Five things that trigger inspections, one of them is, my inspector found mold, but the most common are, I see something, smell something, had a flood or I’m getting sick. Those are the four. So odor calls come in all the time, and they are hard to figure out.
BO: What are the most common odors you are asked? Is there a, this is 80% of the smells I get, or is it not like that?
RS: After mold.
VS: After mold. Yeah, and when it comes to mold, and I’m just gonna go over that a little bit, like wet sheet rock has a very strong odor, you can have one little wall that’s wet, it can make the whole house smell. So that is… I’ve been amazed how one little window leak can make your whole house smell. So that’s wet sheet rock… When mold dries, it doesn’t have a smell nearly as strong as it does when it’s wet, and environment is chronically wet, it’s not just mold, it’s also off gassing of building materials and bacteria that can grow, so damp environments are not… It’s not just mold that’s making that smell, it’s a multiple issue. Well, so then basement carpet, basement carpet has an odor, and that doesn’t even take a flood, I think I’ve talked to every podcast about basement carpet because it remains the number one source of mold, and it’s amazing when you get that out, how the house odor can change and you don’t even have to have a flood to have mold in your basement carpet, if you have an older home with no vapor barrier under the slab, the moisture… The vapor comes in just like the radon, right up through the lab.
VS: And then a lot of people don’t run dehumidifiers, so there’s really two sources of moisture that the carpet is subject to that have nothing to do with leaks, so I always look at the tack strips, if you see rust on the tack strips, obviously if there’s enough moisture just from humidity and condensation… If there’s enough moisture in the rest of the tack strips, there is enough moisture to grow mold that you won’t even see, and it grows in the dust. So it really… Especially, the older the carpet the higher the risk, because more dust.
BO: Are you saying that mold in carpet or on carpet has a specific smell that you can identify?
VS: When you walk into the basement and you smell that musty odor, it can be a couple of things. If it has old carpet, that would be the most likely source, but also sometimes it’s wet cement. So I tell people I’ve been in basements with nothing but cement wall, cement floor, open windows and it smells musty. So my favorite waterproofer showed me a few years back that he had a knee wall open, over the years dirt can migrate into the cinder block holes through the mortar joist. So if you have that ’cause he had an open wall. I said, see that dirt in the cinder block? It comes right through, so if you have wet dirt in there, you’re just gonna have an odor that really has nothing to do with mold. It’s just wet cement.
BO: Would you describe that as earthy or would you describe that as musty?
VS: It’s a very similar… Yeah, kinda earthy and musty. It’s a really similar smell.
TM: Are you talking about, Vickie, the concrete block foundations that have open core blocks open at the top course, the very top course near the basement ceiling where you can reach your hand down into the open core and you’re smelling the dirt through that?
VS: Yep. That’s gonna make it worse, but… So any… This one here was able to show me through the knee wall. So any cinder block, I tell people cinder block has holes in it so big you can put your hand in it, but in some homes that will fill with dirt over time, ’cause he showed me, see that dirt in those holes that just comes through the mortar joints over time. So yes, if you have the open block at your knee wall or the top of your well, that will make it worse, but even if it’s sealed, it’s just damp cement. Has an odor very much like mold.
BO: Okay. Musty is one odor that we’re talking about. What other odor would you label as something you see on a regular basis?
VS: Mouse urine. Do you guys see this?
RS: Hmm, yep.
VS: There was one… Probably one of my most interesting jobs, which there have been so many, the home inspector found what he thought was a leak at the sliding door, because when you went down the basement near that sliding door, there was a stain on the ceiling. So it was natural to presume there must be some sort of leak at the flashing with this door and it’s causing the sheet rock to get wet below. They gave me permission to cut it open. As soon as I got on my ladder with that saw, the mouse urine smell just came out of there. They had so many mice that they had to get rid of that ceiling in the same way that they would get rid of mold, just tear everything down. So it can be…
VS: It can be really extreme. I have a client right now who has never heard of rat mites. Have you guys heard of these?
BO: We don’t want to, either. [laughter]
VS: Yeah, I believe they’re living in her insulation. I read about them, they come from mice and they move into the nest. She warned me before I went down there, “We have rat mites. And I think they’re in the insulation,” so I’m telling her to take off every insulation. She also has a double vapor barrier, another reason to take it off. I didn’t smell the urine in there and I didn’t get bit by the rat mites, but she’s gonna take it all down. So the musty odors are the main ones I get called for. Some people will call, I had one a week ago, it smells like syrup. And they moved into a townhouse and there’s a sweet smell. And I’ve had people call about this, and I have no idea what this is, ’cause I haven’t ended up visiting these houses. But she thought her neighbor was cooking pancakes, but her boyfriend came home at 3 in the morning and said, “The smell is here and they’re not cooking pancakes.” So I don’t know if that comes from some sort of caulk. She could track it down to a plumbing access. I don’t know if it’s some sort of panel or caulk, I have not observed that.
BO: Have you ever, Reuben or Tessa, smelled something sweet?
TM: Sweet like that? No.
RS: Pancake syrupy smell? No.
TM: I haven’t.
RS: No. Never.
VS: Yeah. People have reported it in new homes too. So I don’t know what that is, but I would say the main odors I get called with musty, dead mice, mouse urine, cat urine. Sewer gas is another big one. Sewer gas. I walked into a bathroom in a diner a couple of weeks ago and I could smell it. And I was able to track it down to the sink drain. And you guys could probably tell me better what causes that really musty odor to come out of sink drains.
RS: So there’s a few different reasons why you’d get a funky odor coming out of a drain. The really obvious one is that you lost your trap. The whole purpose of the trap is you’ve got water sitting in here and it’s gonna prevent sewer gases from coming in. Now, if you lose your trap seal, that could cause odors. Sometimes you’ll have, say, a really big house and you’ll have a bathroom that nobody ever uses. Well, the trap seal… The trap can eventually dry out and then you’ll have sewer gas coming in. And the fix for that is just get some RV antifreeze or something like that and pour it down the drain and that stuff will never evaporate, it’s safe for drains, or you can just remember to run some water in the sink about once a month. That will take care of any sewer odors. So that’s the real obvious one. Now, another one though, is that you’ve got some gunk sitting in that trap and it has nastified over a long period of time. [laughter]
BO: That’s a new word. [chuckle]
RS: That’s a real word. That’s a real word, yeah. [laughter] Nastified. Maybe people put hair down the drain and you got this big hair ball stuck in there, and then you get almost a slime that starts growing on the hair and it just… Yeah, I’m painting a great picture, I know, but it does get super stinky. I remember there was one home where I was doing… I wasn’t hired to come out to do an odor inspection, but it turned into an odor inspection on a house that people were living at. And it was a super nasty smell in the bathroom, and we traced it down to the bathtub drain.
RS: And they had what’s called a drum trap on the drain. And a drum trap, it’s different from your typical P-trap. A P-trap is gonna be what we call self-scouring where the water running through it kinda washes everything out of the trap really well, but with a drum trap, it’s this huge… It’s the shape of a coffee can, basically. Water goes in on one side and goes out at the other, and it creates a trap, but you don’t have any cleaning action going on there. So whatever solids go into this trap, anything solid that goes down your drain is gonna stay in this drain, and it turns into a miniature cesspool. It starts decomposing and it is nasty. We traced down the smell to the bathtub drain, and then we go around and we look at the drain, sure enough, it’s a drum trap. And that was the cause of all the nasty odors. And I said, “The short term fix here is clean your trap out. Take the lid off, wear gloves, hopefully… And get all of the gunk in there out and scour the heck out of this thing, maybe use some bleach and get that… “
BO: You’re having a drum trap now?
RS: Yeah. The inside of the drum trap. I mean the long term fix would be replace the drum trap, but for now, what do you do about this nasty odor? Clean it out. So…
TM: Was that a lead drum trap, Reuben? Were they able to get it open and clean it?
RS: I never followed up with them. I don’t know.
BO: There’s no way they got that thing open. It was probably rusted together and, you know. [laughter]
RS: Yeah. And then, other reasons why you might have sewer gas in a bathroom, another not so obvious one, but at the same time, obvious is a broken drain where you just, you have something that’s actually broke and you’ve got a hole in your vent. I’ve seen many vents that have rust holes in them. They rust right where the trap connects. That’s a possibility and you may have a situation where somebody put stuff together wrong, where they just didn’t really understand what the vent was for. And then when they got done with the project, they never actually connected the vent and it just vents into the room. So those are a few possibilities. I’m sure if we add some plumber on the show, they could give us some more things that they’ve ran into, but those are all things that I’ve personally seen doing home inspections.
BO: Vickie, would you say that smells are always worse with higher levels of humidity?
VS: Definitely. I believe that’s a scientific fact. I live near a horse ramp. You don’t even smell it in the winter, but you walk by in the summer, you can really smell it. That’s one reason I tell people, one reason the mold business is twice as busy in the summer as the winter is that people smell their basements ’cause once they go dry and dormant in the winter, they just don’t smell as much and more real estate activities. So those are the two factors that drive the mold business being crazy in the summer.
BO: Are there environmental things that humans do that cause smells to be more prevalent?
VS: Well… [laughter]
BO: I mean, besides cooking, right? The obvious is you smell up the room because you’re cooking. But is there other things that humans do that really accentuate smells?
TM: This is a dangerous question. [laughter]
VS: Yeah. Like I said I’ve done a lot of inspections and I’m not judgmental in this business at all, but I do observe that not everybody cleans. So what I tell people, I’d rather, when I go into a house, I wanna smell neutral, nothing. It’s people have really gotten carried away with these plug-in air fresheners and even diffusing essential oils. So if you clean, your house will smell just fine. If you don’t clean, that can especially dust even can cause a lot of odors. So that’s the main thing I see people doing. I mean, some people cook with a lot of spices, that odor can build up in your house. But I would say cleaning is the number one thing, but I was gonna mention earlier about odors, sometimes when you go into like a ’50s or ’60s rambler, which I think we’ve talked about before are my favorite age home, I am convinced that sometimes when you… They have that old smell and Tess, you’re probably knowledgeable on this. I think that there’s a little bit of mold in all insulation in older homes. It’s there because the condensation, especially in a one story, you’re gonna get a lot of air movement.
VS: I think sometimes when you have that really old smell that you can’t pin down, it’s just from a little bit of condensation that’s happened in the insulation over years or a thin layer of mold inside the walls that would never show up in an air test or people don’t clean their ducts, I guess when I was talking about this, I don’t know what my mom is reading, but she won’t clean her air ducts. I do believe in air duct cleaning, they can build up a lot of dust and if you have a good duct cleaner, that can really change things. And especially the other thing I was gonna mention that causes odors in homes are air conditioner, drain pans that aren’t draining. And then if you get dust on your A-coil, you can get a lot of odors coming out of that air conditioner. And similarly, if you never clean your ducts and you have a 50-year-old house and you put on an AprilAire, you’re gonna get some odor in those ducts. So duct cleaning is really important too.
TM: Can you explain what an AprilAire is for people that are listening and may not know?
VS: Yeah. There are whole house humidifiers. So the sole purpose is to put humidity in through your duct work. And there’s a lot of controversy. To me, it seems like the HVAC guys love these, but the building scientists aren’t so sure. [laughter]
VS: My husband worked on one down in Owatonna. Thank goodness the guy was getting a bid for a metal roof. And so he went up in the attic and he took the time to say, you should get a mold person in here because your attic is really moldy. What had happened, they never had an AprilAire and they put one in and they had the humidity and the temperature both set at 80%, 80 degrees with 80%.
VS: They were loving it because older couple, they were in the tropics.
TM: Oh my gosh.
VS: When my husband went up in the attic, he could wring the water out of the insulation.
VS: So thankfully that roof salesman said something because some people I see like carpet layers laying over moldy tack strips. Some people just do their job. They don’t take the time to say, hey, you should look at your attic. And he probably saved that house because I’ve seen houses, a couple of houses, it’s very rare, but one in Hudson where so much moisture went into the attic because their bathroom fan was venting out this slow pitch, 50 year old, 45 year old rambler. Apparently, two years before we got there, they had to chop off the whole top of their house, new trusses, new sheathing, new shingles, because they had determined somehow that the snow was going to cave in their roof.
VS: So they had water stains for years. Water stains on the ceiling throughout the house, someone had put in an air exchanger to try to help. They remodeled their bathroom. They chopped off the top of their house. And I thought, why did it take us to figure out the problem is this bath fan venting out the side, right under the soffit, sucking all that moisture up and through the soffit for 45 years. And the reason the way we could tell is we went in December, opened up the attic access right over the bathroom. Most of the sheathing was still good because it was only two years old, but right over their bathroom, solid black, solid icy right there. Like, okay. Someone should have figured out when they put that through, let’s vent that bathroom through the roof, not out the side where it goes right into the soffit.
TM: There could have been a few things going on there too with just wall top plate leakage too, with air leakage coming from the hot humid bathroom, going up into the attic and condensing on the underside of the roof along with that bath fan air coming back up into the soffit and condensing on the underside of the roof deck too.
VS: Yeah. So I just I’ve seen so many attic problems caused by these AprilAire humidifiers. I had a really interesting experience where one of the local legacy families, the Daytons, had built a house like a hundred years ago and they had a… When like the first whole house humidifiers I’ve ever seen, it was this huge thing. And a lot of people think, oh well, it’s turned off. It’s not working. These things go rogue and work when people think they’re not working. And that was the case, again, they called me because there was… It only supplied one bedroom and there was mold all over the bedroom. So we traced it back to this ancient whole house humidifier that I’ve never seen before or after, it was working, so I just took it off. So I don’t know, how do you feel about these, Tess? Because I just see ’em causing more problems than helping.
TM: Well, I agree with what you said, the contractors will try and sell ’em, but building scientists have mixed feelings, and I think you can use them responsibly, but moisture is a home’s worst enemy, and that’s what it does, it pumps moisture into the house through the duct work, and so if you’re not careful, you can really have some issues with mold and air quality.
TM: Personally, I’m not a fan of ’em, I don’t like ’em. And if you have… If your house has been air sealed and everything, you shouldn’t need to add humidity, you’ll have enough humidity in the winter time with just showering, cooking, breathing, living, it’s the houses that are really leaky, where there’s a lot of air changes happening between inside and outside in the winter time where it’s really dry outside and it’s humid inside, it’s the houses that are really leaky that are really dry, and so people wanna add humidity to those leaky houses, and those are the worst houses to add humidity to, because all that moisture is going through the cracks into the walls, into the attic, so you’re just compounding an issue.
VS: Interesting, probably causing that general musty old house smell I was talking about, yes.
TM: Very possibly, yeah.
RS: And one more thought on those humidifiers, you say that the HVAC contractors really like ’em, and I might be even more specific with that and say, I think it’s the HVAC sales people who like them. I don’t think the contractors really feel one way or the other, I think it’s just an additional sales…
TM: Upsells. I would agree.
RS: With the sales person, it’s an upsell. Yeah, you want fries with that. You want a blue light filter or a UV filter? Do you want a humidifier? What else can we add on? I think that’s how most of them find their way into houses.
VS: I would agree.
VS: I would agree.
BO: Okay. So let’s switch gears here, I’m really curious to know about your process for narrowing things down. Vickie, can you kind of get into how you begin to solve these issues?
VS: Yeah. Well, so, the main… I tell people the human nose is not like a dog nose. Dogs can track down… They can track down a gas leak apparently 200 feet in the ground. Human noses don’t work like that. But when people call, I always tell my own story that, we’re at a graduation party, my husband smoked a bunch of chicken legs, my friend was running the food, so we ran out of these chicken legs, well, no problem, we have other food, so there are cooked chicken legs that sat in our lower oven for 10 days, and once they started developing that odor, I was… I could smell it. It took me three days to track this down because I didn’t look in the oven, I was looking under my sink, I was looking in my pantry and finding my husband open the oven like, oh, we didn’t run out of chicken legs, here’s 29 sitting right here.
TM: Gross. [chuckle]
VS: So, that was my own kitchen, three days to track that down, so it is very difficult. So a lot of people, when they call, I ask, can you track the odor down to one room, or is it in the whole house? If you can track the odor down to one room, I don’t even visit these houses, I have people wrap that whole room in plastic. So you take big sheets of plastic and you can L-shape… You wrap the ceiling, the wall, and the floor, the whole room, and you can L-shape, but it has to be a separate sheet on the wall, and a separate sheet on the floor. And then you tape these, and you let it sit for a couple days and then you lift the plastic after a couple days, and the odor should intensify behind some of those sheets. So at least you can track down, is what wall, what surfaces that emitting from, that’s half the battle. Again, it doesn’t work if it’s the whole house, but it works really well if it’s one room.
VS: A similar version, and I heard this in a podcast, I think it came from the book, Jeffrey May: My House is Killing Me! It’s a patch test. So it’s a similar concept, you take a paper towel and cut it, pull it in quarters, and take aluminum foil and put these patches all over everything. So now you use the tape and you got the patches on your walls, on your floor, on your ceiling, and then you wait a couple of days and you lift them to see if the odor has absorbed into the paper towel.
BO: The human smell test, you smell the paper towel, you…
VS: So it’s just a little easier, but lot of people use that large sheet plastic, and that is one… Probably the best way to track down an odor. There is, in some cases, a VOC test, there’s… VOC is volatile organic compounds, anything that can release a gas at room temperature, when people have mystery odors, there’s a test that you can get called, at Prism labs, called homeaircheck.com, and sometimes that can tie an odor back to a specific source. So I’ve had people say, well, order the test, they send you a pump and a glass vial, and you run it for two hours and then you send it back to the lab and they tell you what kind of VOCs you have in your air. So, I’ve had people… ‘Cause sometimes these odors come and go, so I just told the woman, order the test and when the odor gets really strong, run it that day because they can sometimes tie those odors back to a source and help you look for that.
VS: So microbial VOCs, back to mold, wet sheet rocks can have a really strong odor that can smell your whole house. What I don’t know is how much mold, active mold, how big of a colony it has to be to show up as a microbial VOC because that is one of the VOCs. But formaldehyde, formaldehyde is a huge problem in new homes, to the point where the EPA has their new program called EPA indoor air plus, so when you order that, if you want a formaldehyde test, it’s a separate tube and it runs for shorter times. So I’m not… It’s gonna be your carpet, your OSB, but that… It’s just another tool in the tool box. I don’t run that, I have once or twice, but I just have my clients run it themselves.
TM: How much do those tests cost, Vickie?
VS: I think they’re about $300.
VS: And I know industrial hygienists can run a lot of VOC tests, but I think Prism’s made it pretty affordable for people to run it themselves, and the customer service is really good. My husband’s pretty good at tracking down odors, and one of the ones… Back to the whole house humidifiers, if people don’t clean that filter, you can get a lot of mold growing on that, and then that’s going right into your ducts. So he went into one that everybody had tried to figure out, and he just walked right up to it, and it was the filter on that humidifier. So sometimes I’ll go into an older house and I can smell the odor, it is very difficult to identify odors.
BO: You don’t have a set process where you walk in and you kinda lead yourself to… Let your nose do the leading, so to speak, and then begin to peel back the layers of the onion when you’re within a reasonable distance from the smell?
VS: No, because like I said, I couldn’t tell those chicken legs were in my oven. [chuckle] It’s really hard. So, you know, when I’m doing an inspection, I will go up to every window and smell the windows in the L-shape corner. ‘Cause if you have a window leak, most of my clients, when they call, they just do that plastic thing or run the VOC test, or I send my husband. He’s really good at it. So it’s hard, I know. I love the calls guys send me, odors are the hardest thing.
RS: Now, I gotta ask you Vickie, something that I heard, you mentioned, Jeff May. And I remember during one… I’m pretty sure it was him who said this. He was teaching at a conference I was at, and I think he talked about using a combustible gas detector when he’s doing odor inspections. I’m wondering if that’s something you’ve ever used.
VS: Is that, you mean like a gas meter?
RS: It’s like a gas meter, but it’s a device that we use as home inspectors to find natural gas leaks. And sometimes we’ll use it to find exhaust gas leaks. And it’s this little device that it’s electronic, you turn it on and it starts making a ticking noise. And as you get closer to a gas leak, the ticking goes faster and faster. Kinda like a Geiger counter or something.
RS: Yeah. Okay. Never? All right.
VS: Well, no, but my husband does have a small gas meter. He bought it for our house, but he’s used it in a couple houses. So there was a couple that was gonna rent a house near us while they built their house. And she said she kept getting headaches in the basement and I don’t get headaches from mold, but I went down that basement and I got a headache almost instantly. So I got near the furnace and I could kind of smell the gas coming out of the furnace. So my husband went over there and confirmed, yes, you should get the gas people in here. Well, they came in and they found two other gas leaks. There were three gas leaks in that basement. So they must have a device like yours, where they… Because I thought, how did they find those other two? But that got all cleared up and they moved into the house with no headaches, so.
TM: Well, a gas leak, just to clarify is different from like back drafting combustion appliances. And both of those things could cause a headache. If you’ve got like a natural draft water heater or an older type furnace that has an open kind of front to it and also a natural draft furnace or some older boilers, like you can actually have combustion gases coming back into the house and not venting up the flu and that would be something that if you called the gas company to come out to find a gas leak, they wouldn’t be looking for something like that necessarily.
VS: So how do you test for that, Tess?
TM: Yeah, there’s a couple different ways. So there’s a test that you can do out there called like a worst case depressurization test where you put the house under like as much negative pressure as you can. And then you turn those appliances on and basically use your hand or smoke or whatever to feel if you can feel those hot gases spilling back out of the vent. And so what we’ll do quick tests is just make sure all the windows are closed, all the exterior doors are closed and turn on all the appliances that exhaust air out of the house to create this negative pressure like closed dryers, kitchen vents, bath fans, and then turn on some hot water and put your hand kind of near the flu at the top of the water heater and see if you can feel those hot exhaust gases spilling back out into the room. And sometimes it just depends on wind and outdoor temperature. And if that water heater’s venting with a furnace up the same flu and the furnace has been running, it’s less likely to backdraft in that situation, because it’s got help from the furnace. So there can be all sorts of different variables that can impact that type of test. You could, sometimes it’ll be just fine and other times it’ll be back drafting. So it can be a little bit tricky to diagnose it. But yeah, those are just some basic tests.
VS: That’s fascinating because, so I always look for combustion air ducts. I’m not an HVAC expert, but I always look to see if you have a natural venting water heater, do you have your combustion air ducts? So what I hear you saying in this test, you put the blower door on, you suck the air out of the house. Is that how you’re creating that negative pressure?
TM: We don’t even use a blower door. We just make sure the house is all closed up. And then we turn on all the exhaust appliances in the house. So it’s just kind of, what’s the worst case kind of possible pressure we could get in the house just with everyday living, not with the help of a blower door.
RS: Yeah. The blower door would be unfair. [laughter]
VS: Well, they tried to look for… Because well the reason the back drafting appliances… So I had one a long time ago. It was pretty new and I went there in February and they told me that their mold started flat and then became three dimensional like this isn’t mold. You are growing mushrooms in your sliding door. I walked up the house, you could tell the house was dripping, every once when I see these houses in the winter where the windows are so wet, it was dripping. What had happened is the combustion air duct, the venter didn’t like the cold air coming in through the combustion air duct so she put insulation in there and I think what was happening is these backdraft and because as soon as she took out that insulation after three days, the house totally normalized with its humidity, but the carpet was so wet.
VS: Like when I leaned on the floor to look at the carpet, my pants got wet. I’ll never forget that. And people, I think I might have mentioned this in another podcast, a house in Elco, the combustion air duct was clogged. And what happens in a lot of houses, the intake for the air exchanger on the outside of the house gets clogged and people say, well, I had my HVAC I hear you looked at… They only look at the box. You have to go outside to this small hole on the outside of your house where your air exchanger air’s coming in. In this case, both of those intakes were closed. So I tell people an air exchanger is gonna send air out of your basement, your house constantly. And if it can’t pull it in, it’s gonna find a place. So in this case it had a really high water table because it was near a creek and the knee wall, in the family room, half the knee wall, the cement wall, a lot of times you’ll see wood on the top of the knee wall.
VS: These people just had sheet rock. The moisture pulled up through that cinder block to make that whole sheet rock on the top of the knee wall moldy. And right now I’m working on one in Plymouth, a townhouse on slab, the combustion, the intake duct for the air exchanger was like 12 feet off the ground. So the HOA takes care of it. So he didn’t clean it last winter. ‘Cause they were like, “Well, how come this is only happening in this guy’s unit?” Well, look at his vent is totally clogged. He went to Florida for the winter, came back to mold everywhere around the perimeter because the air exchanger was sending it out, couldn’t bring it in so it pulled it under the sill plate everywhere in the townhouse and now he has mold like a $20,000 mold problem from that one little hole being clogged.
RS: Oh no.
VS: So these air exchangers, like I tell people, 50% of the people that have them, I said, do you clean the vent outside your house, when they look at me like, don’t know what you mean. 50% of the people that have air exchangers don’t know they’re supposed to clean that or they rely on their HVAC company. And that little 8-inch hole is crucial.
BO: I just wanna touch on one thing. Tessa went into kind of a long explanation of finding it, but there’s two different tools that home inspectors use. One, smells for gas or propane. Then there’s a combustion gas analyzer that some home inspectors use, and that would tell you if these combustion gases that are created by ignition are in your living environment. So you can check it out with tools as well. Okay, let’s change gears again and let’s talk about deodorization. Can you get rid of smells? You have wood in your house. Can you deodorize wood or any of these things that you simply just can’t tear out? Or is everything gotta be encapsulated or removed and re-installed?
VS: So I’m not an expert in that area, but this is what I know. A lot of the deodorizing techniques have been developed for fire restoration. If you have a house fire, your whole house smells like smoke. So they have developed these techniques for the things that won’t be removed. Ozone is the big… I hate ozone. I don’t like people to breathe in ozone in small air purifiers that use ionizers or UV lights or electrostatic plates, because that puts small amounts of ozone into the air and can irritate your breathing. But ozone used in small doses to deodorize is a really powerful tool. The fire restoration companies will have chambers like let’s say you did have a house fire and they take all your furniture to the offsite cleaning facility. They put them in ozone chambers. Ozone is amazing, and it destroys odor molecules. I don’t know the science behind it, but it’s a very powerful deodorizer. There’s another version called hydroxyl generators that is similar but apparently people can be there and breathe it in when that’s being used or chlorine dioxide fogging has come on the scene a couple of years ago and I think that can be used for cigarette smoke and cat urine. So those are the three big deodorizing things that you can put in your air.
VS: I do think there are some encapsulants. Like I said, I’m not an expert in that, but I do know that’s the three tools. And there’s actually some companies out there, a lot of the restoration companies will do it. The chlorine dioxide works amazing for certain odors. But there’s a guy with a company called EIEIOdors that’s just doing out there… I think he does a lot of pet odors…
TM: That’s a great name.
VS: Doing this. Of course, remove the source, as Bill was saying. Again, you got moldy carpet, remove it. So a lot of times, you do have to remove the source, but if you can’t, then it’s ozone hydroxyl or chlorine dioxide.
TM: Do you think you can get cigarette smoke out of a house if you… Let’s say the house had carpet in it. You remove all the carpet and it still smells, what would you do? Would you paint the walls with a certain chemical or would you do the gas, or the ozone, or something?
VS: And I’m not trained in that, but I’ve always wondered why if they’re using ozone or chlorine dioxide, why don’t they put positive pressure? Because some of this stuff, I keep talking about the stuff inside the walls that we don’t see, I don’t know if this is a thing, but they could put a blower door on and create positive pressure and push those deodorizing things into the walls. I don’t know why they do that.
TM: That’s an interesting thought. Yeah.
VS: ‘Cause some people are doing inner-wall air testing for mold. They make a hole in the wall and they put the air tester in the wall. I don’t know if you guys are doing that. I’d shy away from that.
TM: We’re not doing that.
VS: Yeah, especially next to your walls because one of my competitors, who I totally trust, put 20 holes in a wall and got like 12 spores. And the mold guys are like, “Should I really open this wall for 12 spores?” Because, again, I contend in cold weather climate, we heat and cool. There’s some condensation that builds up in our walls. Probably every little bit of insulation in every house has a little mold in it.
TM: Yeah, it seems like a pandora’s box.
VS: Yes. Yes. We don’t have… So interesting, especially the 100-year-old homes. Two-story, 100-year-old homes because of that positive pressure trying to escape the top of the house, I know that they get a lot of mold. I’ve seen it. But the 100-year-old brick… So when people call about their 100-year-old homes, I ask, Is it stucco, wood siding or brick? The brick buildings don’t have a wall cavity, so they don’t develop that mold. 100-year-old brick building is a pretty stable building because there’s no wall cavity to condense. But all of the stucco and the wood can get a lot of condensation, especially on the upper levels, that will lead to a thin layer of mold that some people can’t live around.
BO: I’m fascinated by mold, but I’m happy to pass along all of these requests to you Vickie. So.
TM: Well you and your bloodhound husband, it sounds like.
VS: Yeah, I give him the odor stuff now. He’s good at it.
BO: Glad you’re willing to fight this fight, ’cause I think most of us have said, “Yeah, not our deal.”
VS: It’s hard. In fact, I almost thought I should have contacted that industrial hygienist who claimed 80% of the time he could figure out every odor, but he claimed to be an odor expert. And what I heard is that 20% of the time, even he couldn’t figure it out. It’s hard.
RS: Yeah. Yeah, it’s challenging.
VS: But we try.
BO: Well, I think we’re gonna bring this episode to a close. It’s starting to stink a little bit, so probably time to wrap this bad boy up. But Vickie, thank you very much as always for your time. We really appreciate the weird environments you go into willingly. I think most people would try to avoid them with all cost. But hey, you’re out there doing a great job, so thanks for your service.
VS: Yeah. I’m super curious so some houses, I just can’t wait to get there.
BO: Remind everybody where to get ahold of you if they need you.
VS: Phone number: 612-508-2742. Website, mnmold.com, mnmold.com.
BO: Outstanding. Well, thank you and thank you everybody for listening. You’ve been listening to Structure Talk, a Structure Tech presentation. My name is Bill Oelrich, alongside Tessa Murry and Reuben Saltzman. We’ll catch you next time.
VS: Thanks for having me.
BO: Hi, everybody. Bill here again with Structure Talk. We really wanna thank you for listening to this podcast. It’s been a ton of fun for us to put this presentation together. And if you could, we would love it if you would go to any of the podcast platforms where you find Structure Talk and leave us a rating and subscribe to the show. You can also subscribe to our blog at structuretech.com, and of course, you can listen to the show on the internet at structuretalk.com. Thanks again for listening. We appreciate the support. And if you have any suggestions for show topics, please email them to firstname.lastname@example.org. Thanks for listening.