Attention Home Inspectors: The IEB Summer Mastermind is coming up on August 2nd. Details here: https://events.iebcoaching.com/IEBSummerMastermind2024#/
In this episode of the Structure Talk podcast, Reuben Saltzman and Tessa Murray discuss dryer ducts and the importance of fire safety. They cover the materials and thickness required for dryer ducts, the size and location of vent terminals, and the maximum allowable length of dryer ducts. They also share personal anecdotes and recommendations for maintaining dryer ducts. The conversation emphasizes proper installation and maintenance to prevent lint accumulation and potential fire hazards. They discuss various aspects of dryer ducts, including size, length, terminals, and materials. They explain that the maximum length for a dryer duct is 35 feet, but manufacturers often allow for longer lengths. They also discuss the importance of proper installation, including using UL-listed foil tape or mastic to secure the ducts. They caution against using indoor dryer vent kits and plastic corrugated vents, as they can pose fire hazards. Reuben recommends having the dryer duct professionally cleaned annually for longer runs.
Check out these links for the blog post related to Dryer Ducts:
Inspecting Dryer Ducts:
Are flexible foil dryer ducts code-approved?:
Video: Burning Dryer Ducts:
Takeaways
Dryer ducts should be made of solid material that resists lint accumulation and contains fires.
The code requires dryer ducts to be four inches in diameter to maintain airflow and prevent clogging.
Vent terminals should not have screens, as they can trap lint and reduce efficiency.
Dryer ducts should be installed in accessible locations to facilitate cleaning and maintenance.
The maximum allowable length of dryer ducts is typically 35 feet, but manufacturers’ instructions should also be followed. The maximum length for a dryer duct is 35 feet, but manufacturers often allow for longer lengths.
Proper installation of dryer ducts is important to prevent fire hazards and maintain efficiency.
UL-listed foil tape or mastic should be used to secure dryer ducts.
Indoor dryer vent kits and plastic corrugated vents are not recommended due to fire hazards.
Dryer ducts should be professionally cleaned annually for longer runs.
Chapters
00:00 Introduction and Weather Update
03:05 Discussion on Mosquitoes and Product Recommendation
08:21 Introduction to Dryer Ducts and Transition Ducts
12:17 Requirements for Dryer Ducts
17:35 Vent Terminal Requirements
23:28 Maximum Allowable Length of Dryer Ducts
30:18 Avoiding Fire Hazards: Indoor Dryer Vent Kits and Plastic Corrugated Vents
34:06 Maintaining Efficiency: Professional Cleaning of Dryer Ducts
45:46 Conclusion
TRANSCRIPTION
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.
Reuben Saltzman: Welcome to my house. Welcome to the Structure Talk podcast, a production of Structure Tech Home Inspections. My name is Reuben Saltzman. I’m your host alongside building science geek, Tessa Murry. We help home inspectors up their game through education, and we help homeowners to be better stewards of their houses. We’ve been keeping it real on this podcast since 2019, and we are also the number one home inspection podcast in the world, according to my mom.
RS: Welcome back to the Structure Talk podcast. I am your host Reuben Saltzman, along with Tessa Murry. Tessa, how are you doing today?
Tessa Murry: Hey Reuben, I’m doing well. Thank you. How are you doing?
RS: I’m doing great. Where are you podcasting from today, Tessa? Where in the world is Tessa Murry?
TM: Where in the world is Tessa Murry? [laughter] Well, I’m in Florida, sunny Florida, and it’s like 95 degrees out, and like the dew point’s like 92, so it’s quite pleasant.
RS: Oh, my goodness. Oh, we are blessed in Minnesota here, and now who knows what it’s gonna be like when this airs. It’ll be a couple of weeks from now when this show airs, but at the moment, the weather couldn’t be any more perfect. Like if I could just design a perfect day, it’s like zero humidity, gentle breeze, 75 degrees, the sun is shining…
TM: Oh, my God.
RS: All the windows of my house are open; it’s glorious.
TM: Beautiful, beautiful, absolutely beautiful. Now you step outside and you just immediately start sweating. That’s what people say.
RS: Oh, yeah.
TM: So I’ve been enjoying a pool and trying to stay in the shade, and the mosquitoes are terrible too. I don’t know about you up in Maple Grove, but I know where I live in Red Wing, Minnesota, mosquitoes have been ferocious this year, ’cause of all of the rain. Even in the daytime, they still are just on you the moment you’re outside, and same thing here in Florida, although what would you expect? I mean, it’s sloppy, it rains every day, but it’s the same thing here. I can’t go outside for more than two minutes without getting bit, so gotta D up.
RS: So that’s the mosquitoes this year. Oh, my goodness. Yes.
TM: Do they bite you? Do you get bit?
RS: Oh, I do. I do.
TM: You do? Okay.
RS: I was at a friend’s house and they were hosting this party for the youth at my church or whatever. And so I stopped by to hang out with them for a little bit. And he’s given me a tour of his property. He’s got like three acres and he’s like, oh yeah, I got to show you this fort my son was building. And he takes me in the thick of the woods. He’s like, let’s be quick ’cause the mosquitoes are pretty bad. Tessa, I couldn’t even listen to him talk. I’m like, all right, dude, dude, that’s good. It’s awesome. It’s awesome. Let’s go. ‘Cause I had them like all over my neck. And I mean, just, and I would try to move constantly, but I think I had about 20 on me at the same time.
TM: Oh, my God.
RS: And I ended up with like all of these lumps on my neck and legs in this 30 seconds I spent in that deep forest area. They are so bad, but I will tell you…
TM: They are ridiculous.
RS: I’ll share a product. The manufacturer needs to compensate me somehow.
TM: I’m sure they’ll listen to this podcast.
RS: I’m sure they do. It’s now I’ve seen them pop up all over. And I got, my wife got one. It’s called the Thermacell. Have you seen these things?
TM: No. What is that?
RS: It’s this little, well, they’ve changed shape, but it’s this little portable device. It’s about the size of a toilet paper roll. And it runs off of a fuel cartridge. It’s a replaceable fuel cartridge. It’s like butane or something. You put this fuel cartridge in, you click this little clicker and it ignites it. And then it heats up this little replaceable pad that the pads last like four hours or something like that. And it wards mosquitoes away and it does a pretty darn good job. It’s supposed to create like a 15 foot radius that mosquitoes will not enter. And it’s not perfect, if you’re outside and it’s kind of breezy. I don’t think it’s that effective, but on a calm day, you set that thing outside. And after a few minutes, the mosquitoes tend to go away. And I used it at the cabin. I was doing a workout in the garage and there was mosquitoes just everywhere. And I set the thing up before I went out there. I let it sit for about 15 minutes, went out there to do my workout. And I didn’t see a single mosquito. So there’s my testimonial for it. Found it to be extremely effective.
TM: What’s the name is it called again?
RS: It’s called a Thermacell.
TM: Thermacell.
RS: Therma, like I don’t know, temperature like a thermos, but Therma, and then cell, C-E-L-L.
TM: Cell.
RS: And I don’t know where she got it, but I was at Home Depot the other day and I saw them right on an end cap, right by the entrance. So I think you can probably buy them anywhere now.
TM: So it puffs out this chemical in the air?
RS: Yeah, I’m sure it’s good for you. Don’t worry about it.
TM: I’m wondering what it is. I mean, ’cause actually I was talking to some friends this year that live out in Jersey. Shout out to Sam and Joe, lucky Joe. But they were talking about some kind of mosquito thing they had too that worked that way as well. They kept it outside around them and it kept the mosquitoes away. And I can’t remember what it was called, but maybe it’s the same thing.
RS: I’ll bet you it’s the same thing. Yep. Yep. Probably is. I’ve seen more expensive options…
TM: Well, interesting.
RS: Like the Mosquito Magnet and it’s this thing that’s supposed to attract mosquitoes, but it takes like a 25 or a 20 pound… Propane tank and it does all this other stuff. It’s, I mean, they’re like 500 bucks. The Thermacell.
TM: No way. No way.
RS: These are like 20, 25 bucks, something like that. So.
TM: Okay, sounds good to take, good price.
RS: There’s my product of the week.
TM: I like it.
RS: I’ve had good luck with it. And you know what…
TM: Thank you for your recommendation.
RS: While I’m promoting stuff. Oh, yeah, of course. Yeah, I’m promoting stuff, Tess, got to give a shout out to IEB Inspector Empire Builder. As I mentioned in the past, they are a sponsor of the show now. We’re partners with them. Like I said, I’ve been a member for a long time and I mentioned on last week’s show, but got to mention this week. This show is going to air on July 29th. Later this week is IEB’s summer mastermind. This is a all day event. It’s being held online. Home inspectors can attend on Zoom. And if you’re a member of IEB, it’s free. If you’re not a member, there is a very small registration fee. I think it’s like 99 bucks or something. One of our previous podcast guests, Daniel Felt, will be one of the featured speakers, Daniel Felt of Cura Home. And I’m looking forward to it. It should be great stuff. If anybody wants to go, I will have a link to that event in the show notes. Please register. Love to see you online there.
TM: And Daniel Felt built a kind of a home maintenance company from the ground up here in Minnesota, and it has just exploded. So he’s going to be talking about kind of his business. Right. And how he found success.
RS: Yeah. And I think his specific topic is, what is it? It’s…
TM: Scaling a business?
RS: No, it’s…
TM: It’s definitely how to do that.
RS: Recurring revenue. Recurring revenue.
TM: Okay. Oh, recurring revenue.
RS: That’s what it’s about.
TM: Okay. Very interesting. There you go.
RS: From, here’s the title: From One Time Deals to Lifetime Clients. Yeah.
TM: Hmm. Okay, great.
RS: Got to throw in a plug for that. Hope to hope to see some of our listeners there.
TM: Perfect.
RS: Okay.
TM: It’s wonderful.
RS: Back to the show.
RS: All right. So mosquitoes…
TM: What’s our topic today?
RS: Yeah. Mosquitoes are terrible. We all know that. We all hate them. Today, we’re not talking about mosquitoes, though. Today, we’re talking about the topic of the week related to the blog post.
TM: Hit me.
RS: Huh?
TM: Hit me. Hit me.
RS: All right. You ready to drum roll? We’re talking about dryer ducts. How’s that sound?
TM: Oh.
RS: How fun is this?
TM: Super, super exciting. Well, hey, Reuben, if anyone can make dryer ducts exciting, it’s going to be you.
RS: We’re going to try. We’re going to try. I’ve done so much messing around with dryer ducts. You know, I don’t know if you remember, but I actually had someone from the Family Handyman come out and we did a video shoot where I set up a rig in my backyard. I got a bathroom exhaust fan to simulate a clothes dryer exhaust fan. And I hooked it up to all of these different dryer ducts or dryer transition ducts, I should say. And I ended up stuffing all of them full of shredded paper and lighting them on fire and then hooking the fan up to see how fast we could get a fire to tear through the side of this dryer transition duct. It was great.
TM: Best experiment ever, that you’ve done.
RS: I thought it was tons of fun. Yeah, yeah, that was that was a good video. I will surely put a link to that show notes here. But I just used a term that…
TM: I didn’t realize that was Family Handyman that did that with you. Okay.
RS: Yeah. Yeah. They wanted to do it. It’s like, heck, yeah. Come to my house. Let’s do it. Although we picked a day. It was in the fall and it was freezing out, Tessa. I mean, it was like 20 degrees. And I’m trying to not be all super bundled up because there’s no snow on the ground yet. So you don’t know how cold it is. But I mean, I should have been wearing a hat and all that other stuff. But I just, I thought I’d try to wear my my light Structure Tech jacket, but I had to wear a sweatshirt and another sweatshirt underneath. So I’m just super puffed out like the marshmallow man or something because I’m wearing all these layers trying to look like I’m wearing a light spring jacket.
TM: It’s funny, I know what video you’re talking about because I used it. We used it for the training for Structure Tech Home Inspectors.
RS: Oh, good.
TM: And teaching them why it’s important to inspect dryer ducts and what they should look for and why some of these materials could be dangerous. And so I remember watching that video, but I’m going to go back and look and admire your winter wear. [laughter]
RS: Yes, yes, it’s great.
TM: Just to recall.
RS: But I just realized I used a term that we should define right at the beginning here. I said dryer transition.
TM: Dryer transition duct.
RS: Yes. So.
TM: What? Okay, why does that matter? What is it?
RS: Well, the code has two different terms. You’ve got the dryer duct, and that’s the stuff that conveys the exhaust from your clothes dryer to the exterior. And it’s, well, we’ll talk about all the rules for it. That’s your duct. And then you’ve got this other thing called the transition duct, which you’re allowed to use to get from your dryer to the duct. It’s not dryer duct. It’s just what you get to the duct. And that stuff can be flexible. You can use corrugated stuff and you can bend it, whatever. And I know a lot of home inspectors are like, oh, you should never use that stuff. Well, the code allows it. And if you have a dryer pushed up against a wall and there’s no way to access it, how the heck else are you supposed to connect your dryer? I mean, you need to use that in some cases.
RS: At my house. I’m lucky enough, at my last house, somehow the dryer was installed right against the wall. You just push the dryer in and it connected to it. At the house I’m at now, I can reach behind there and I can use all rigid material. I don’t need a transition duct, but in a lot of cases you do. So it’s a different beast. All right, Tess, what should we talk about? Should we talk about dryer ducts or transition ducts first? What makes more logical sense?
TM: Let’s talk about dryer ducts. Let’s talk about dryer ducts.
RS: All right.
TM: What should a dryer duct be? Why does it… Reuben, and why does it even matter, what does look like?
RS: Well, it all comes down to fire safety. You can’t use some material that’s gonna be super thin, that’s gonna get clogged, that’s gonna get kinked. That’s gonna break. It needs to be a solid material that will resist lint from accumulating. And if a fire does happen inside there, it should contain the fire until the lint burns out. That’s the idea.
TM: Really?
RS: Yes.
TM: It should contain the fire. The lint will burn, but the duct will not.
RS: Yes. And for all of these different materials that I tested, if you had just lint in there, these would all surely contain that fire before it ripped through the side of a steel duct.
TM: Wow.
RS: And part of it has to do with what it’s made from. The Minnesota code says that you need to use material that is 0.016 inches thick, which comes out to 27 gauge steel. But you’re not gonna find 27 gauge steel. So you need to go up one size, which basically means 26 gauge steel. Which is, it’s beefy material.
TM: So, okay. I have a few questions for you. So this is Minnesota code talking about that specific gauge.
RS: Yeah.
TM: I mean, is there like a national standard for what dryer ducts should be? There’s someone listening to this in a different state, like should they check their state specific code for what it requires?
RS: Yes. Most likely, in a lot of the country, they use the International Residential Code, the IRC. And if you get the full book, you turn to the mechanical section of the IRC, which Minnesota just doesn’t even use at all. But it would be under section M as in mechanical, 1502. M1502, that’s where you find all the rules for dryer ducts and dryer transition ducts. And in the national code, it’s pretty much the same. They’ll actually let you get away with 28 gauge steel in the national code. But who cares? I don’t know how to measure the difference between the two metals. I don’t know how to tell the difference between the two. If I see solid metal on a dryer duct, I just assume it’s fine. I ain’t measuring that and I wouldn’t expect any home inspector to do that.
TM: Well, that was gonna be my next question is, when you go to like Home Depot or one of these hardware stores and you look for a dryer duct, is that what you’re buying? Like do they just… Do you have to worry about products being available on the market that you should not use?
RS: Well, as far as the dryer ducts go, I’m gonna buy whatever Home Depot’s selling. I’m not gonna be too worried about that for the duct. Now, for the dryer transition duct, if you wanna get into that, hold on, let’s come back to that. There you need to worry. But for now, let’s talk about some other rules for the duct itself. It needs to be four inches, Tess. That’s it.
TM: Can’t be smaller than that. Four inches minimum diameter.
RS: Can’t be smaller, why do you think it can’t be smaller?
TM: And my guess is it reduces restricts airflow and it can, it’s more likely to clog with lint and start a fire.
RS: That’s exactly it. Now, why can’t it be larger? Because remember, I said it needs to be four inches. I didn’t say at least four inches. I said four inches.
TM: That’s a good question. Why can’t it be larger? I have no clue, Reuben, you’ve stumped me.
RS: All right, Tessa… All right, good, good, ’cause I’m excited. I’m gonna do a demonstration for you that our listeners will really appreciate. I’ve got a spitball here that I’m chewing up in my mouth and I’ve got a straw, there, I just shot the spitball at the camera. Tessa is dying. Okay, that works really great, huh? Okay, that’s your traditional dryer duct. Now, we’re gonna increase the size of that dryer duct. Now I’m holding up a toilet paper tube and I’m gonna put my spitball in the toilet paper tube and I’m gonna give it even more breath. It just kind of fell out.
TM: Yeah.
RS: There. That’s why you need to a four inch duct.
TM: Wow. You know what, Reuben, I wish our listeners could have seen that visual, but let me just describe it to y’all. That little straw catapulted that spitball out at the screen, it went flying out versus toilet paper tube, it kind of just, like you said, fell out.
RS: Yeah, it kind of falls out.
TM: So we want a four inch duct for some velocity in that air that’s exiting, right?
RS: That’s the word, Tessa. That is exactly it.
TM: Okay.
RS: Yep.
TM: Ding, ding, ding. Interesting.
RS: And if you don’t have that velocity, you’re gonna greatly increase the potential for lint accumulation in that whole duct. So in this case, bigger is not better. Needs to be four inches.
TM: Yeah. Very interesting. Okay. Okay. What about the actual… Now you didn’t bring this up and since we’re kind of moving from the outside in, I’m picturing it dryer duct being on the exterior, connecting the outside vent terminal. Are there requirements for the vent terminal too?
RS: Yeah. You can’t have any screens on the vent terminal. How many times have you seen that, Tess? You’ve got a story about that, don’t you?
TM: Go ahead, Reuben. Bring up this story. This so point, I’ve healed from it. Okay. It’s fine. This was years ago.
RS: This wasn’t even anything you did. You were just there.
TM: It was traumatic. Okay. I know, but I hate making mistakes and I hate being the source of any stress for anyone. And it was a little stressful, I’ll admit. You tell the story, Reuben.
RS: All right. Well, I’m gonna botch it, ’cause it wasn’t my story, but the way I remember it was that you found a dryer terminal and it had a screen on there and it’s totally clogged with lint. There’s nothing coming out. And you told the buyer, yeah, dryers aren’t supposed to have that. And this very aggressive buyer of yours went up to the terminal and she’s like, oh, I’m gonna fix that. And she took it off and she’s like, there, I’m saving lives. There’s no fire that’s gonna be happening. And then later our office got a call complaining that the home inspector removed the pest guard that had been installed around the dryer and what right does she have to go fixing my house and changing stuff and now I’m gonna get mice coming in my house. And what are you guys doing, that’s the long and short of it, right?
TM: Yes. And I’d say almost like 50% of the dryer ducts that I see out there have some sort of screen over them. And we’re not talking like a small mesh screen, usually, it’s kind of some sort of like plastic grate that’s, I don’t know, quarter inch, half inch between the little, the grid line. So it’s not like a, it’s not a… In my mind, it’s not like a screen on a window. It’s a plastic kind of cover on it. But it’s very common for those dryer ducts to have that. And people think you need it to keep the mice out, keep the pests out, but really those screens just catch the lint and then block the vent. And if you’re not maintaining it properly, you can, it’s a fire hazard, potentially.
RS: Yes.
TM: And it reduces, the efficiency of the dryer. So then you have a dryer that’s not working the way that it should and clothes that aren’t drying. And I think one of the most problematic locations for a dryer exhaust terminal is on the roof of the house for a three story townhome, which we also see a lot. Who’s gonna go up there and especially if you’ve got a three story townhome that has a screen on the dryer vent terminal. Even worse, even worse situation. Who’s cleaning that?
RS: Tessa, totally agree. Yes. I’ve been to a number of houses where I’m doing an 11-month warranty inspection. The people… Homeowners have been there for less than a year and they tell me they’re having problems with their clothes dryer. It doesn’t dry the clothes, but they get really hot and they stay really damp. And then I go on the roof… And they’ve had manufacturers out and the builder out, nobody can figure out what it is. It’s so simple. You go on the roof.
TM: Oh, my gosh.
RS: And when you go to the store and you buy a vent terminal, it’s the same terminal, whether it’s a bath fan or a clothes dryer, and it comes with this screen. If it’s a bath fan, you leave the screen on. If it’s a clothes dryer, you take the screen off, but the poor roofers, they don’t know what it’s for. They just know there’s a duct coming through the roof. And they use the same thing on everything. And if you don’t have a diligent person on the job site, removing that screen afterward, it stays that way. And then after a year it’s completely blocked with lint and you got wet hot clothes and potentially a fire hazard. I mean, let’s be honest, probably not after a year, but eventually, yes.
RS: And nobody can get at it. Yeah, no screens on there, and Tess, Amen to your dislike of having them terminated on a roof or nobody can see them much less and many times access them.
TM: Yeah. Why can’t we just vent them out the side of the house?
RS: Yeah. But I will say, vent them out the side of the house with an asterisk, to a sensible location. Here’s a story for you, Tess. Just recently we were doing a home inspection. We had done the pre drywall inspection. The dryer was set up to vent through the roof. And we said, ideally, this should be rerouted to a more accessible location, such as a sidewall. Believe it or not, the builder rerouted it. Nobody ever reroute system.
TM: You’re kidding!
RS: But they rerouted it and they rerouted it to the gable end wall up by the roof, which was three stories in the air, on a hill.
TM: What story, what level was the dryer on? Was it on the second floor of the house?
RS: On the second floor. Yeah. So now I would argue it’s possibly even less accessible, ’cause now you need a two-story extension ladder. Whereas before all you needed was a one story ladder to get on the roof to get at it. So it’s like…
TM: Wow. Yeah. Shoot, man. Okay. Well, thank you builder for listening to us. But also maybe you shouldn’t have, and you know what, though? At least they’re not gonna be melting snow on their roof, which could contribute to potential ice stamps. So you don’t have to worry about that. But you will have to get your big ladder out to clean it.
RS: Yes. Exactly. At least you’re not contributing to ice stamps. That’s a great point. And you can see it too.
TM: So here’s another question for you, Reuben. Is there something in the code that talks about the an acceptable length for a dryer duct?
RS: Yes. Great question. Glad you brought that up. The code says you can follow a couple different paths. One of them is you just follow what the code says. They give you the cookbook, they give you the manual, they say 35 feet. That’s it. And that doesn’t include the length of your dryer transition duct. That’s not part of the calculation. It’s just the duct itself, the permanent part, 35 feet, maximum. And if you’re gonna have elbows on there, they’ve got all these different calculations. For instance, if you’ve got a tight 90 degree turn, you gotta subtract five feet. That’s worth five feet of run. So you get four turns, you lose 20 feet right there. But it’s kind of a formula. That’s what the code says. However, it also says that you could follow the dryer manufacturer’s instructions instead. And I’ve read probably dozens of dryer manufacturer’s installation instructions and…
TM: Stimulating reading, evening reading.
RS: Stimulated this is what I do, Tess. I’m curious tonight, I read manuals.
TM: This is how you fall asleep at night.
RS: That’s right, and just for instance.
TM: A little light manual reading.
[laughter]
RS: Yeah. What’s the big deal? Here’s four different manufacturers. We got Maytag, LG, Kenmore, Samsung. I just checked out theirs, just for fun. Their lengths, their allowable lengths, developed lengths are 64 feet, 65, 64, and 80 feet.
TM: Whoa, okay.
RS: And that’s in line… Those are just averages that manufacturers allow. I’ve never seen a manufacturer limit their vent to 35 or their duct.
TM: 35 feet.
RS: Excuse me. It’s a dryer duct. I’ve never seen them limit it to anywhere close to 35 feet. It’s all way more than that.
TM: That’s very interesting. And I wonder, are there… Do you ever run across cities or city inspectors who have a problem with the dryer duct being 60 feet? ‘Cause they call out the code and it says 35.
RS: No.
TM: Okay.
RS: As long as there’s a dryer present. Now, the one time where you could have an issue is if you have a new construction home and the developed length is more than 35 feet and we don’t know what the dryer manufacturer is gonna be.
TM: True.
RS: Now, what do you do? And the code does have some special provisions for that. I’m not gonna get in all the details, but they say, maybe you can put in a placard, it, you know what? Okay, I am gonna get into the details 504.85.
TM: For our one listener that appreciates all of the details and gets a little testy, if we don’t tell them. Here we go.
RS: Let’s say, just for fun. It says where the exhaust duct equivalent length exceeds 35 feet, the equivalent length of the exhaust duct shall be identified on a permanent label or tag. And it shall be located within six feet of the exhaust duct connection. Tessa, have you ever seen one of these tags?
TM: I was trying to picture that in my head. No, I have not. Have you?
RS: I saw one, it was about 15 years ago and it was at a condo in St. Louis Park and it was a very nice tag. It was, embossed, it was… You know the door tags that you’d have for the president of the company and it’s embossed or whatever, it was just like that.
TM: Like gold plated.
[laughter]
RS: Yes, it was gold. I kid you not, the color of it was gold. And they spelled dryer, I won’t forget this. I don’t know why I remember this detail. They spelled dryer, D-R-I-E-R.
TM: I-E-R. Oh, no. You went to that trouble to have a label and you misspelled dryer.
RS: Yeah.
TM: Reuben, your brain is so impressive. How do you remember this from 15 years ago? And do you have the picture of that? I wouldn’t be surprised.
RS: I will find picture for you, Tess. Of course, I have the picture.
TM: You have a picture of that? Oh my Gosh. Of course, you do.
RS: And then you ask my wife if I remember things, she’ll tell you a different story. It’s very selective, very selective memory.
TM: So stiff memory. Yes.
RS: Yeah, just the very important stuff.
TM: Remember that dryer duct from 15 years ago? Oh, shoo, that missed our anniversary.
RS: Yeah. And I can’t remember what to get up the store. She tells me to get two things at Target and I come home with one. You know, I know.
TM: 50% of the time you get it right every time.
RS: Yeah. I like the way you put that. Yeah.
[laughter]
RS: Okay, so we talked about size. We talked about length, we talked about terminals and… Oh, and you know what, also about terminals. Tess.
TM: Yeah.
RS: You, can get these things. I’ve got one sitting around here. You’ve surely seen these during home inspections. I’m holding it up to the screen. Tessa, describe for your listeners, for our listeners what I’m holding up. What is this thing?
TM: Okay.
RS: That I picked up at Home Depot yesterday.
TM: Yeah, I think what you’re holding up is one of those little diverters that, it’s a little transition. The dryer duct goes through it and it has a little opening on the side, a little door that can open and, usually there’s a screen in there and basically, it just blows that warm air from the dryer exhaust back into the house.
RS: That’s exactly it.
TM: Is that what that is?
RS: Yes. It’s an indoor dryer vent kit. And it says right on here vent, electric dryers when outdoor venting is not possible. And it’s UL listed. This is listed for electric dryers ’cause there’s no hazardous exhaust gas. However, from a building science standpoint, Tess, how do you feel about venting your clothes dryer to the inside of the house, taking all that moisture in the clothes and putting it back into the house?
TM: If you wanna feel like you’re in southern Florida with me when you walk outside and the dew point is a few degrees lower than the temperature.
[laughter]
RS: Yeah.
TM: Put one of these on your dryer. It’s a great, put… Gosh, huge contributor of potential moisture to your house and indoor air quality problems and could lead to mold and other health issues. So not something I’d recommend.
RS: No. And furthermore, the Minnesota mechanical code does not allow these, says that dryers, regardless of the fuel type, need to be vented directly to the exterior. And the national code says the same thing. It’s not just a Minnesota requirement.
TM: Really?
RS: Yes. You cannot do this anywhere.
TM: And they’re still being sold.
RS: They still sell them. It’s legal to buy them and own them. You just can’t install them. That’s all.
TM: Just like, corrugated drain pipes, fittings.
RS: Yeah. Exactly. Yeah. So, none of those. They need to vent to the exterior.
TM: Okay. No bueno. We don’t want those.
RS: All right, we’re almost done with dryer ducts, couple of little things.
TM: I’m was gonna ask you one more quick question about the dryer duct thing.
RS: Yeah.
TM: Do you have to, how do you properly secure different lengths of dryer duct. Do you use screws? Do you use tape? What should you be looking for?
RS: Well, in the Minnesota code they specifically say you can’t use screws, and the idea is that screws are gonna penetrate into the duct. Lint’s gonna accumulate on there. Personally, I don’t think it’s that big of a deal. I don’t… I wouldn’t lose sleep over it, but that’s the rules. You’re not supposed to use screws. And you’re also not supposed to use duct tape or masking tape or any other types of tape other than the foil tape, it’s UL listed. It’s gonna be the 181B-Fx. It’s the foil tape and love Tess we would use this during our home inspections for miscellaneous stuff; it’s great. But if you go to the store…
TM: All the holes we drill and duct were, I guess, [0:32:40.1] ____.
[overlapping conversation]
RS: All the holes we drill, yes. You go to the store and you buy foil tape. There’s two different rules of foil tape. One of them costs 12 bucks and it’s just generic plain foil tape. Well, the other costs 25 bucks and it’s the UL listed stuff. There is a big difference between the two. So get the UL listed stuff. I was at the store the other day and they actually sold a really small thin roll of it. I’m holding this up for Tessa. It’s a very tiny roll of the same material.
TM: Oh, look at that.
RS: It’s the same listing. It’s 181B or FX, B-FX. And it says right on here, it says dryer vent installation. This is dryer vent installation tape, they’re calling it, I call it clever marketing. And they can sell a very small roll for a high dollar amount. It’s the same as my huge roll. But…
TM: It is. Okay.
RS: If you only need a little bit, I guess, it makes sense. You don’t need to buy this huge roll of it. So that’s what should be used or mastic. There’s a mastic that has the same rating. Once it’s applied, you don’t see it too often. It’s only professional installers use this stuff and it looks basically like the color of duct tape. It looks gray and it’s like somebody gooped it on all the joints. That stuff is allowable too, but it’s very unusual to see that.
TM: Okay. So if you’re inspecting a house, you wanna see that UL listed foil tape, ideally at all the seams.
RS: Ideally. Yeah. And we don’t get super whipped up if things all look good. If we see duct tape, we say, Hey, it’s not the best way to connect it. Maybe you wanna redo these connections. And nobody in the history of our entire company has ever redone their connections based on our recommendation. I suspect, but still.
TM: Yes. Okay. All right. Did we cover all the pertinent information about dryer ducts, you think?
RS: I think we covered all the stuff that people regularly get wrong. Yeah.
TM: Okay. That’s helpful. So what about the material that’s allowable for the dryer transition ducts? This little section that connects the dryer to the dryer duct.
RS: All right. So the…
TM: What can you use for that?
RS: Well it’s really simple. You use something that is UL listed and it’s gonna be UL 2158A. As long as it’s got that UL listing, you’re good to go. And there a few different products that we commonly see. One of them is gonna be corrugated aluminum. And it’s this stuff that, it’s all smooshed together when you buy it. And then you can stretch it out. You can stretch out one lengthy, the up to eight feet, kind of a slinky material. That stuff is allowable. There’s a UL listed type of it that’s really strong, really hard, you can’t crush it. And then there’s a non UL listed type, which is much thinner and you can smoosh it with your hand pretty easily. I can barely tell the difference between the two looking at them. From a home inspection perspective, I don’t try to figure out which one it is. As long as it’s the corrugated aluminum, I’m happy with it. So that’s…
TM: Okay. You don’t make a big deal about that?
RS: No, and based on the testing that I’ve done and lighting fires on them and seeing how they perform, I don’t think it’s a huge difference. That’s one material. Another one would be what I know a home, a lot of home inspectors really hate this stuff. And it’s the flexible foil duct and it’s basically what I’m describing.
TM: Yeah.
RS: It’s flex foil. It’s a lot thinner. It’s a lot easier for fire to rip through this stuff. However, if it’s properly installed and you have a short a length as possible, this is a UL listed product, it is acceptable to use it. Now some manufacturers don’t like it. There’s a handful of clothes dryer manufacturers that say you can’t use that stuff. And some of them even have confusing manuals where it says in one part, you can use something that’s UL 2158A listed, and then in another part they say, don’t use foil. It’s like, well, what if it is UL listed? I don’t know. When we see it, we don’t make a big deal about it. I don’t think it’s the best product to use. But I’m not the authority on it. If the authorities have tested this stuff and they say that it’s safe enough, I’m not gonna tell people to tear it out and replace it.
TM: I think I see probably more foil used out there than aluminum. Would you say that’s because it’s cheaper and, maybe easier to work with?
RS: It’s because it’s easier to work with.
TM: Okay.
RS: I, personally I don’t like working with that corrugated aluminum because once you get it to the size or the place you want it, it’s not easy to move it around. And if you do accidentally smoosh it, it doesn’t return to its original shape. And…
TM: Yeah.
RS: It has really sharp edges. I have personally…
TM: It does.
RS: Gotten a nasty slice working with that stuff at a house I used to live in Minneapolis. I mean, I was, well, I won’t get into it.
TM: It’s tough.
RS: But it was a nasty slice, so it could be dangerous too.
TM: You bled everywhere?
RS: Yeah, a lot of blood everywhere. Yeah.
TM: You left your DNA all over, is like a crime scene when you were done.
RS: No, of course. Anytime you’re working with stuff like that, you ought to be wearing work gloves. But.
TM: You should, you should.
RS: You should, you should.
TM: What about, okay, so what about plastic corrugated vents? Because I see a lot of those too.
RS: Never, never, never. The plastic itself is actually flammable, so no, that’s bad news.
TM: Then why do they, why are they available? I mean, how is that allowable? If they’re a fire hazard…
RS: Well, I’ll tell you what.
TM: And they’re not allowed, How can we still purchase them?
RS: I was just at Home Depot and I went through the whole dryer duct, dryer vent section and it was nowhere to be found. So applause, that was great. However, I’ll show you this other product I picked up, which I was not excited to find. It’s a thing called a flex foil duct. It says, Ideal for gas and electric dryer application, and it’s the flex foil duct that I just described. But it’s a 25-foot length of this. 25 feet.
TM: No.
RS: And furthermore on the same product it says UL listed. It doesn’t say what standard it’s listed to. So what is this thing for?
TM: That’s confusing. Reuben, did you say what the maximum allowable length for a dryer transition duct is based on the code?
RS: I don’t know if I did or not. It’s eight feet.
TM: I don’t think so. Or maybe you did.
RS: Okay, eight feet.
TM: Okay. Eight feet. So 25 feet is clearly too long for what that type of flexible material should be used for.
RS: Yeah. Yeah. And now is it the same material as the one they would sell in an eight-foot package? Probably. So could you just cut off some of this and use less than eight feet? Probably, but I don’t know. And as a home inspector when I see it, if I see less than eight feet, am I gonna know the difference? No way.
TM: No. Yeah. Well, the whole point of this is, I mean, you wanna have a smooth, rigid material for as long as possible to reduce the potential for lint getting stuck and trapped and for reduction in efficiency of the dryer and reduction of fire hazard. So I mean, you want that smooth transition. The more flex duct you have, the more likely you are to have problems with drying and potentially fire. So.
RS: That’s exactly it.
TM: You just, 25 feet is not ideal. Not good and not allowable.
RS: No, no, no, no, no. We would definitely call that out if we saw that during the home inspection.
TM: I think it’s, you know what, it is pretty common to look behind a dryer and see just a lengths of that foil stuff just coiled back and forth behind the dryer, and you can put hole on it.
RS: Yeah. They buy a 25-foot section. And they use all 25 feet to run four feet.
TM: Yes, yes, yes. [laughter]
RS: Yes.
TM: By gosh, they bought that product and they’re gonna use every linear feet of it. Linear foot of it.
RS: Yep. Exactly.
TM: Okay. All right. Are there any other materials that are allowable or that someone might run across when they’re inspecting?
RS: Sorry, I have somebody running a lawnmower right outside my window. I hope you can’t hear it, but I couldn’t hear you.
TM: I cannot, I was just wondering if there’s any other materials we didn’t cover that we should for these dryer transition ducts.
RS: You know, there’s one other one I’ll mention, and this is one called Dryer Flex. And I first tested their product probably 12 years ago where they sent me a sample of it. And it’s kind of a hybrid between the foil and the corrugated aluminum. It’s just as easy to work with as a corrugated aluminum, but it’s way better than the standard corrugated stuff you get. It’s, I mean, it’s super thick and it’s very resistant to a fire spreading out of there, lot’s of stuff, if I have to use corrugated stuff in my house, I’m using the stuff made by Dryer Flex and that’s a manufacturer. I don’t know of any retailers that you can just walk into and purchase it at. You can order it online and I think they sell it in like four or eight-foot sections. That’s the gold standard, if you ask me.
TM: Just to clarify, you said it so it’s easy to work with like the foil flexible duct, but, it’s more durable and rigid, like the aluminum, corrugated aluminum?
RS: Yeah, it’s like a hybrid between the two and it’s way thicker than the single ply foil.
TM: Foil? Okay. Okay, that’s helpful. Interesting. Well, you know, I was thinking, when I was kind of remodeling the condo I had in the Twin Cities years ago, I had to replace that dryer transition duct and I found some product that was like this magnet connector that, ’cause it was a really tight space and I physically couldn’t kind of get behind there. So I connected one section of that transition to the dryer and then the other section was a magnet and it kind of just snapped in place to the dryer vent in the wall. And I can’t remember what it was called, but it was a very helpful product in that situation.
RS: All right, Tess, give me like two seconds and I’ll find it because I’m sure it’s made by the same people as Dryer Flex. So let me go to their website.
TM: Wow. Okay. And maybe you even, you might have even told me about it back then, ’cause I struggled with that, trying to figure out how I was gonna connect the dryer and you probably told me about it, so.
RS: Yeah, you know what, maybe it’s not made by them ’cause I’m on their website and I don’t see it. All right. We don’t know who it is, it’s probably awesome.
TM: Google it. Yeah.
RS: Yeah. I’m, I can picture what you’re talking about.
TM: Magnet Dryer Transition Duct. Yeah. Yeah. Okay. Well.
RS: All right.
TM: You wrote a very helpful long blog, Reuben, on this topic that lays out all of the rules, all the recommendations, all the UL listing requirements, lengths, all of that. Is there any other information that we should let our listeners know about what to look for with a proper dryer duct installation?
RS: You know, that’s all I can think of. There’s probably other stuff we’re missing, but that, covers the high points. And the, last one is if you, if you have a short little run like I do where it runs right up the side of the house, and I, you probably don’t need to worry too much about cleaning it. I think we’ve talked about this when we talked about our fall maintenance, our regular fall maintenance list, talking about cleaning your dryer duct. But if you’ve got a long run, it’s, it would be good to have that professionally cleaned, probably annually to make sure you don’t get a bunch of lint accumulated in there, creating a potential fire hazard.
TM: Annually is your recommendation. And is, and you said professionally done, is there, are there tools that a homeowner can rent or buy to do that themself? Or why do you have to have it done professionally?
RS: Well, a professional is gonna have the really long stuff that’s gonna go all the way through the duct, to get the whole thing done. If you have a very short run, I think you can buy like these little six foot sections. It’s basically you’ve got a cleaning brush on the end of a steel flexible rod, kind of like a bottle brush, basically. You can use that to do it yourself. I’ve heard of people, I think we’ve talked about this on the podcast, disconnecting their dryer and hooking up a leaf blower and then just really blowing all of that to the exterior. Seems like it might work, but I’ve never tried it myself.
TM: I think that could be another little, video blog for a later date, Reuben. It looks given.
RS: I would love, yeah, I’d love to go to somebody else’s house who’s got a super long run and connect my gas backpack leaf blower up to it and see what happens. Wouldn’t that be delightful?
TM: Okay. Maybe not.
RS: Well, as long as it’s somebody else’s house, who cares?
TM: Any volunteers? Let us know. How do they reach us Reuben? [laughter]
RS: Please. Yeah. Please email us Structure Tech. No, now I’m flustered, Tessa. Podcast, Tessa’s dying here. Podcast@structuretech.com.
TM: All right, well this was a fun one and I, you know, we’ve talked about dryer ducts longer than I thought we would, but that’s usually always the case, isn’t it, when we get into it?
RS: It’s a fun topic, Tess, come on.
TM: It is.
RS: All right, Tessa.
TM: If anyone’s still listening, thank you for listening. We appreciate all of you that are listening to our podcast and we’d love to hear from you. Please, write us an email if you have any feedback or any ideas on topics. We’d love to hear from you and help us out by giving us some reviews and ratings too. If you listen to this show, we would appreciate that as well, so.
RS: Yeah, anywhere you listen, please, please give us a rating. We would appreciate it. All right.
TM: Well, thank you so much. Reuben, it was good to see you again as always. And…
RS: Good to see you, Tess. Thanks for giving up your pool time. I’ll let you get back at it.
[laughter]
TM: All right, working on the tan this summer.
RS: All right. Well, I will catch you next week.
TM: Sounds good.
RS: Take care.
TM: All right, take care. Bye-bye.