If you've been listening to the show for a while, you may recognize the name Natalie Bogwalker because she's been a guest in the past! Natalie is a wealth of knowledge about natural building techniques. In today's show, we are going to do a deep dive into two natural building techniques: slip straw and hempcrete. I went in knowing nothing about these and I asked really basic questions and Natalie really did a wonderful job explaining everything. Natalie also tells us all about how her online building school, Wild Abundance, had to shift to online learning during the pandemic and how she's now created what sounds like a pretty amazing online tiny house building course.
In This Episode:
- How Wild Abundance adapted and thrived during the pandemic
- Are online classes as effective as in-person classes?
- Slip straw vs cob: what's the difference?
- Natalie explains the slip straw technique
- Should you use slip straw in your THOW?
- What is hempcrete?
- Why we need to be using thatched roofs
Links and Resources:
- DIY Paint: Beautiful and 100% Natural on Natalie's blog
- Online Tiny House Building Class
- How to Build with Aircrete with Hajjar Gibran
Natalie Bogwalker has been building and living in tiny homes of various natural varieties for almost 20 years. She runs Wild Abundance, where she facilitates in-person tiny house classes, women's carpentry classes, natural building classes, online building classes, as well as classes on permaculture, gardening, and more.
This Week's Sponsor:
Tiny House Engage
Tiny House Engage is a really special online place where you can connect with other tiny house hopefuls, people who are DIY building their tiny houses, buying tiny houses, and even living the tiny house lifestyle. It's a really supportive community and there are a lot of cool features and bonuses that you get when you are a member of Tiny House Engage, one of which is that you are actually able to listen live as I interview all the podcast guests and you are even able to submit questions for the show. You'll hear in this conversation with Natalie that there are actually some really great questions that I was able to ask on behalf of Tiny House Engage members and I would love to be able to do the same for you.
If you'd like to learn more and get on the waitlist to be notified when Tiny House Engage goes live on Tuesday, head over to thetinyhouse.net/engage.
The outside of a slip straw structure is covered in plaster
Wild Abundance teaches women carpentry skills
Most of their classes are outdoors
Cob can make keeping windows clean difficult
Natalie has enjoyed tanning hides for a long time
DIY earthen paint samples at a workshop
Natalie Bogwalker 0:00
But for those who have had math trauma, like it's super empowering and my partner who, you know, we would build together, he'd be like a half an inch plus one little line.
And that's a common experience for a lot of people.
Ethan Waldman 0:16
Welcome to the Tiny House Lifestyle Podcast show where you learn how to plan, build, and live the tiny lifestyle. I'm your host, Ethan Waldman, and this is episode 170. With Natalie Bogwalker. If you've been listening to the show for a while, you might be nice to name because Natalie has actually been a guest in the past. Natalie is a wealth of knowledge about natural building techniques. And on today's show, we are going to do a deep dive on two natural building techniques. The first is called slip straw. And the second is called hempcrete. I went in knowing nothing about these. So I asked the really basic questions, so you don't have to. and Natalie really did a wonderful job explaining everything. This one will really benefit if you head over to the show notes for this episode, because I have photos of a lot of what we talked about. That's at the tiny house dotnet slash 170. And then Natalie also tells us all about how wild abundance her building school had to shift to online learning during the pandemic, and how she's actually now created. What sounds like a pretty amazing online tiny house building course. So we cover all that in more, and I hope you stick around for the full conversation.
This is a special week here at the tiny house dotnet headquarters because my online community, Tiny House Engage is opening for registration. Starting this coming Tuesday. And Tiny House Engage is a really special online place where you can connect with other tiny house hopefuls people who are DIY building their tiny houses, buying tiny houses, and even living the tiny house lifestyle. It's a really supportive community. And there are a lot of cool features and bonuses that you get when you are a member of Tiny House Engage. One of which is that you actually are able to listen live as I interview all of the podcast guests, and you can even submit questions for the show. You'll hear in this conversation with Natalie, that there are actually some really great guest questions that I was able to ask on behalf of Tiny House Engage members. And I would love to be able to do the same for you. Though if you'd like to learn more and get on the waitlist to be notified when Tiny House Engage goes live on Tuesday. Head over to thetinyhouse.net/engage. Again, that's thetinyhouse.net/engage e n g a g e. All right on with the show.
Alright, I am here with Natalie Bogwalker. Natalie has been building and living in Tiny Homes of various natural varieties for almost 20 years. She runs wild abundance, which facilitates in person tiny house classes, women's carpentry classes, not for building classes, online building classes, as well as classes on permaculture, gardening and more. Natalie Bogwalker, welcome back to the show.
Natalie Bogwalker 3:21
I'm so happy to be here with you, Ethan. Thanks for having me again.
Ethan Waldman 3:25
You're welcome. Happy to have you back.
You know, it's been a while since we talked, I will, I'm gonna guess over a year since you were here. You know, on our, on our last show, we talked a lot about your story, kind of your background of how you came to found a building school. And then we talked a little bit like we did kind of an overview of some natural building techniques.
And so today, you know, I was hoping that we could do more of a deep dive on, you know, one or two natural building techniques. But I was first just hoping to have you tell us, you know, how how are things going? You know, it's, it's June 2021 right now in the US is kind of coming out ish of the pandemic, you know, how, how have things been going at Wild Abundance through this last year?
Natalie Bogwalker 4:19
Well, it has been a whirlwind. And when we first got news about the pandemic, our staff was very confused. pretty overwhelmed. We're like, Oh my gosh, we're gonna have to cancel our classes. We're gonna go out of business. And so we, we just got on and we're not going to be able to help our students you know, and not gonna exist anymore. And luckily, we are a fairly resilient bunch of people. So, we have we started the online gardening school which did not exist prior to April of 2020, so we started that.
And we were, we realized at some point that, because our classrooms are all outdoors, that we would just require masks, and that we could still run our classes. So last year, we canceled a couple, just a couple of classes. And then we still ran our in person, tiny house class and our women's basic and advanced carpentry classes. And so that was such a blessing to be able to keep serving our folks and to be able to just have have some stability.
One big change was we have the in person, tiny house class, the way that it works is, it's a pretty good sized group of people, there's typically 30 to 35 students in it. And we would do all the lectures all together at a local university. And then we would split the class up to do all of the hands on natural building techniques, and for the tiny house builds. And so the smaller groups felt very comfortable, but the big group did not. So we chose to take all the lectures from the class and put them online. And then when we finished with that, we were like, "Oh, well, this is a good, good bit towards having an online tiny house class". And we kind of like accidentally ended up offering an online tiny house pass. So we are right now in the midst of really beefing that up and creating more hands on, quote unquote, virtual content, so that the class can stand on its own really well and be really helpful to folks who are not able to come to our in person, tiny house class, because we not only is there like the travel issues with getting here, but we currently have a waiting list of 1700 people for that class.
So, you know, not everyone is going to get into the class, you know, we opened some of these classes up and they fell within well, within an hour. And so we're really hoping to offer that content to a wider audience, because we just don't have the capacity to serve everyone that we would love to serve in person. And there's, you know, it's expensive to come, you know, to a place, leave your whole life for a while, and pay the tuition and all of these things. So we were wanting to create also just an accessible option for folks who are wanting to learn step by step, how to build a tiny house. So it's pretty exciting, tiny houses and not so tiny houses. And it's a class that we're especially, is especially geared towards women, or anyone else who has felt disempowered with building in our culture, which is, which is, you know, not a small percentage of people. So we just really, it, we just got really excited about making this content accessible to people. So in the many different ways, so that's awesome.
Ethan Waldman 8:12
Yeah, one of the I mean, I feel like one of the challenges to go online is that, for those who feel disempowered by the world of building, you know, they may never have picked up, you know, an impact driver or a circular saw. And part of the magic of the in person class is that you, you know, you can actually say, yeah, it's, it's okay, let's do this, you're gonna you're going to use this circular saw, and we're going to, you're going to make sure you're safe. We're gonna watch you do it. Yeah. You know, how do you handle that in the online setting?
Natalie Bogwalker 8:46
Well, not only do we go through the basics of the circular saw, we go through the basics of the tape measure, along along with about 15 other tools. And that's because we have a lot of experience teaching these basic tool skills, because we've taught, at this point, dozens of women's basic carpentry classes. And so some of the same teachers that teach those classes and who have fielded hundreds of questions about each of these tools are the people who we've engaged to be teaching these tools classes. So that feels really good to me. And it's, you know, it's interesting because I also have an online hide tanning class. And that's a that's a skill that, you know, no one thinks of as being something you could teach virtually, because it's just such a, such a hands on kind of abstract skill. That's also very, you know, it's a it's a primitive skill. It's a skill that is, is very Earth based. Yeah, and the feedback that we've gotten from that course, because we are very thorough people. Is that oh my gosh, I never thought it would be possible, but I like tan this hide. And it's like it was like so easy given like the given the step by step instructions that you get.
So we feel really good about it. And so, you know, there's everything in that course from hands on, you know how to read a tape measure, like believe there's a lot of people out there who have some math trauma. And, you know, obviously, many of the students who take the class won't watch the tape measure class. And that's the glory of this class is it's really a library of classes. So you watch the ones that you need to watch, and you don't watch the ones you don't need to watch, right. But for those who have had math, trauma, like it's super empowering, and my, my partner who happens to be male, is one of these people and like, you know, when we would build together, he'd be like, a half an inch plus one little line.
Ethan Waldman 10:51
Natalie Bogwalker 10:52
And that's a common experience for a lot of people. So we really break it down and really take the mystery out of it. And I think really, like get people feeling empowered, you know, from the very ground up from the tape measure and how to properly sharpen a pencil, so you won't be frustrated, as you're using it in the difference between a carpentry pencil and a regular pencil. And like, you know, so there's basics like that. And then there's, like, you know, different types of roof design, and how to implement those different types of roof design. And there's, like, there's electrical, like, we go way into electrical. And, you know, part of the electrical do is we say, you know, definitely, depending on where you are some places, you just have to hire an electrician, some places you can do it yourself, but you need to have someone who's licensed, look over your work and make sure you're not going to start a fire.
But whatever the case is, we go from very basic techniques, to pretty advanced techniques, and cover, like how to, like just basically every single step of building a tiny or not so tiny house. So yeah, I feel really good about it. We talked about advantages of being on wheels versus on a foundation, we talked about code, we're actually soon going to have a free class. This kind of a prelude to this, the bigger class which is, which is 10 Ways to Save Money Building a Tiny House too, which is a big deal in this day and age with fluctuations and lumber prices and all this stuff.
So yeah, I'm feeling really proud and excited about this team of folks who come together. And it's really a team like I'm teaching, I'm teaching like, I think less than 1/10 of the classes.
Ethan Waldman 12:40
Natalie Bogwalker 12:41
So there's this whole team, which is like more than half women instructors, which I feel really good about and, and instructors from lots of different walks of life and backgrounds and all this stuff. So it's just feeling it's feeling really solid.
Ethan Waldman 12:57
Awesome. Well, that's, that's so exciting. Congrats for kind of turning lemons into lemonade there.
Natalie Bogwalker 13:04
Yeah. That's what we try to do.
Ethan Waldman 13:08
Yeah, yeah, or turning, turning tides into, into leather jackets, I don't know, there you go. Where does one even get this one get a hide to tan? I wouldn't even know where to start.
Natalie Bogwalker 13:24
Typically, we are tanning deer hides. And this is something like in my, in my younger life, I spent a lot of my time doing primitive skills. So I, I'm also really into wild foods and all of this stuff. And, and with hide tanning. This is something I'm, I'm honestly a little more into building these days than I am into, into building clothing. But deer hides typically are pretty easy to come by, if you call up a deer processor, so hunters often take their deer to a deer processor. And those processors, you know, turn the animals so to speak into meat, you know, and so they bring in the deer and it comes out in packages. I really like the you know, butcher my own deer if I'm doing that, which is not a huge part of my life in this this segment of my life but has been, but it's a great place to get hides, and they're just often taking them to the dump.
So it's this beautiful interruption in the waste stream and like I've had, I've had several vegans take the class because they and I I taught this in person for about a dozen years before we did the before we did the online version. And that's I think what really what really makes an online class awesome is someone who has a ton of experience teaching it in person so they know all the questions, you know that come up, right? But whatever the case is, we've had vegans take the class because they didn't see any cruelty going into getting the hide like basically it's like interrupting the waste stream. Right? It's already there.
Ethan Waldman 15:07
Natalie Bogwalker 15:09
So, and it's just such a beautiful and ancestral process. But yeah, so that's another online class.
Ethan Waldman 15:16
Natalie Bogwalker 15:18
Yeah. And that one still happens in person too, though. That one still happens in person too. And Tyler Lavin Berg, who was my apprentice about 10 years ago now teaches that in person.
Ethan Waldman 15:30
Natalie Bogwalker 15:31
And yeah, it's crazy was wild abundance has grown. The amount of in person teaching that I'm able to do just with running the whole organization is has changed quite a bit. So we have like, a lot of amazing features that I feel really good about.
Ethan Waldman 15:48
Cool. Yeah, let's jump into, you know, a couple of these natural building techniques. Yeah. Because, you know, last last time we spoke, we talked about a lot of different ones. And I believe we spoke, you were in your house. And it's built with remind me, I can't remember,
Natalie Bogwalker 16:10
it's a log cabin
Ethan Waldman 16:11
Natalie Bogwalker 16:12
So the the initial build was a 12 by 16, log cabin, two floors. And then I did a couple Additions on it, which I think is just such a fabulous thing to do if you have a tiny house, because a lot of people build a tiny house, then they have a kid and they're like, "Ah, this tiny house thing doesn't really work."
Ethan Waldman 16:32
Natalie Bogwalker 16:33
So being able to whether it's a mobile unit that then you might might later if someone purchases land, or whatever, it might become a permanent unit, or whether you start off with a permanent unit, I think planning for expansion is a really good idea if you're building a tiny house. So then there's an addition. That is that use Well, it's a timber frame, structurally. And then it uses slip straw, which is a pretty cool natural building techniques. So that's one of the additions. And then the other addition, is using just standard stick framing, but with wood that is sourced locally, rough sawn lumber, and then I use some traditional lime plaster techniques.
Ethan Waldman 17:21
Natalie Bogwalker 17:21
And on the inside on the interior and parts of that
Ethan Waldman 17:26
Extra cool. Well, that's a perfect segue because, you know, slip straw really caught my interest. And you know, we were chatting a bit before we started rolling. And I was like, "Well, I don't even know what it is." So let's, let's start there. Like what what is slip straw?
Natalie Bogwalker 17:46
Totally. So that's an excellent question. So slip straw is made from basically the same materials that you would make cobs from. But while cob is incredibly laborious, in my opinion, and I've done a lot of cob stomping, to create and requires an extremely beefy foundation. cob is also a thermal mass material, which is appropriate in certain parts of the world. But in the part of the world where I live in where a lot of probably your listeners love, an insulative material makes more sense.
And so straw like can be on just a post Foundation, it is doesn't have to be as thick as cob, you can get away with like eight or 10 inches of thickness. And it is very fast. Like of all the natural building techniques, I mean, all these natural building techniques, I mean, there's a lot to be said for them in that they're relatively inexpensive, if you're doing all the labor yourself. And they're using totally non toxic materials. They're really, they're really, really fabulous in so many ways, but the amount of labor that goes into them is something that is often not talked about. And that's why a lot of these techniques like like you often don't only see people building with Cobb, if they're having a problem workshop.
It's so labor intensive. And if you don't have the time to do it yourself, there's no way you can pay for the labor. It's just so expensive, whereas slip straw, and hempcrete are both techniques that where the labor is, is much more reasonable, it's still gonna be more laborious than conventional construction.
But when if you were accounting for the cost of the cost or the labor that goes into or the cost anyway, that goes into a lot of these techniques, which are really not good for the earth, then I think that it would be a wash you know, yeah, but yeah, so, so strong. clay is way less laborious, that means it does not have the same foundation heavy duty foundation requirements that cob does. And it is insulated. So why so it? Is it not as heavy because the inside of like in a cob wall, it's just the entire wall is all essentially clay. Whereas basically, strat is it that you're kind of piling up straw and then like encapsulating it in clay. Yeah. So with with cob, you are creating a clay wall, where straw is basically the rebar holding it together. And it's basically it's almost like you're creating a rock, rock, but it's pretty darn close to it. And so it's primarily clay and sand, the cob wall, and the proportion of Clinton just depends on the soil that you're using the subsoil, okay. And with straw clay, basically, what you do is you stay, you take a straw, and you coat it in just a thin clay slip, there's no sand involved. And then you use like the,
the wall structure that's holding it up because the the straw clay is not load bearing is very similar to just a conventional stick framed wall, which is how almost all buildings are framed in this country. And so it's a really nice thing to be able to access more conventional building techniques, because our culture is set up to be able to do those really efficiently. And so you can frame up a wall, very similarly to how you would frame it up if you were just doing standard construction. And then you use wall forms, which is like just made out of plywood, or you could use board. If you don't want to use plywood, you do like a, it's, it's interesting, because I have videos on this, and I have all sorts of pictures that really help help represent this, but it's a little hard to explain without the pictures.
But basically, you you have like a stud framed wall that just has like two by four studs, and then or a different size. And then you take two pieces of plywood, and you put them on either side of this stud wall. And typically you use spacers or some other technique, you can just put in screws and not sink them in all the way. Okay, so that those plywood forms are not being sucked up to the studs were held out from the sides, okay. And then you take straw, and you coat it in a thin clay slip, you stuffed it into the wall, and you have to tamp it a little bit into the corners, but you don't want to tempt you don't want to compress it too much, because then it won't be as fluffy because fluffy equals insulative.
Right and then after you stuffed it into the wall for however high your your plywood form is you can immediately unscrew your plywood form and move it up. And you just have to overlap it about eight inches or so. And then you can stop it in to the next section like so you can actually finish a straw clay wall if you have enough, you know, person power and like efficient enough technique in a day. It's really amazing. And that's that's even faster than hempcrete you can only do two feet in a day but because of the amazing interlocking glory of the straw, you can you can get a lot done at once. So yeah, I have a good bit of experience I lived in a straw clay cabin that I built pushin 20 years ago, it was my first tiny house it was eight feet by 12 feet and it was tiny.
But um, but so that was the first cabin that I ever built. After I attended a bunch of natural building workshops and then actually apprentice so to speak with my partner who was a carpenter and then learned how to actually build a lot of natural building classes all they teach you is how to put clay on two walls but but we we go deeper because I was jaded by that and I had to go and learn carpentry on my own so we like to teach the two together.
And and yeah, it's a it's a pretty cool technique. I think that it is not the most insulative material like you know straw bale is way more insulative and there's other like I think hempcrete is more insulative as well but also way thicker right like a straw bale wall it's gonna be like yes foot and a half thick or something. Yeah, it's gonna be way thicker depending on which way you which way you put the straw bales. Yeah. But you know when you're talking tiny, like a straw bale wall will take up a huge amount of your footprint. And like again, here I am talking about things that when I teach I usually have a whiteboard demonstrating but, but like if you have, you know, a 12 by 16 footprint, and you're using bales that are putting to half the footprint that you're left with, like if you start with like, a 200 square foot ish footprint, and then you have to take up the whole perimeter with a foot and a half thick material, you're left with a really small space inside. And that that consideration of how much how much percentage of your footprint, the walls take up is a significantly higher percentage when you're talking about a small footprint than if you're talking about like a 20 by 40 house. Right, right, where it's not that significant. So for me and also, you know, tiny houses are so easy. And so if you're going tiny, I think that a straw bale really doesn't make sense unless you're in a very cold place.
Ethan Waldman 25:56
Right. So with with the straw bale after you've you know, coated that straw in a light, light play slip and kind of packed it in. Is there an additional coating that gets applied, you know, inside and outside to kind of finish the wall?
Natalie Bogwalker 26:15
Yes. So with slip straw, the straw bales a whole whole nother story. Okay, which I think you just you just misspoke, which I do all the time. Yes. Just to clarify and see why. Yes, yes, there's so many straws and bales and slip and all this stuff. So after, um, after you build the wall, you wait for the wall to dry out, which in some climates is quite a quick thing. And my climate being that I live in a temperate rain forest in the southern Appalachians. It can take like, you know, I'm on 3-6 weeks
Ethan Waldman 26:49
Natalie Bogwalker 26:50
And then after that point, you and during that time the wall was sometimes actually sprout because straw while it is the byproduct of grain production oftentimes has a little bit of grain or seeds left in it. Your wall will sprout a little bit but then the spouse will die as the wall dries up. And and then you apply plaster. And so that posture can be an earthen plaster or it can be a lime based plaster, but you should never use stucco on any sort of earthen wall because stucco does not breathe in the same way that lime plaster and earthen plaster dots.
And I prefer to use on my log cabin on the chinking. And also on my log cabin, where I did the addition that was slip straw. I use I like to use a lime plaster for the exterior, and then an earthen plaster for the interior got it. And that's because the lime is just much more resilient to getting wet. Like if you get if you get earthen plaster really wet if you like spray it with a hose for an hour, like it turns back into mud and spray a if you spray a lime plastered wall with a hose for an hour. It is not the same effect because lime plaster basically turns into limestone and which is pretty awesome. But for interior use, there's just it can be really lovely to work with earthen plasters, and that's something our class goes into quite a bit. Our online class and or in person class is you don't even need to work gloves when you're working with earthen plasters, which is so lovely. And then I like to finish off the interior with an alis or earthen paint, which, you know, you can go with all sorts of different colors and you can put mica in it, which is fabulously sparkly.
Ethan Waldman 28:47
Natalie Bogwalker 28:48
And the earthen paint the alis is something that's not just limited to doing in an earthen structure, you can also do it on top of drywall. And that's something I've done a lot of and it's really lovely for transforming a more conventional space, one that just has to be built more quickly into or with less labor into a really earthy feeling place. So yeah, alis, it's amazing. We have a blog about it on our website.
Ethan Waldman 29:20
Okay, well, I'm gonna link you know, and for those who who are regular listeners of the show, you'll know that you know links for everything will be on the show notes for this episode. And this will be episode number 170. So it'll be at thetinyhouse.net/170 for links to as much as I can find of what we talked about.
Natalie Bogwalker 29:45
Ethan Waldman 29:45
I have a question about slip straw and I'm going to try to not call it the wrong thing as technology's everyone severely. So with I know with cob it is kind of structural in this That, like, if you want to add a window, you can just kind of as you're building up your cob wall, essentially just like "Yep, I'm going to put a window here and then like cob around it." With the slip straw, do you frame the windows and doors in like conventional construction, you know, with a king and a jack stud and a sail and all that?
Natalie Bogwalker 30:22
Yes, you do. You do. And I find that to honestly be well, it's not as organic is definitely more simple and works a lot better than doing it with cob. So yeah, I I really, I mean, it cob is great for fixed windows, and you can have like all sorts of cool shapes around him. But then when it comes to keeping the window clean, yeah, heavy like mud wall interfacing with glass, it's pretty challenging. And so that's something that I really appreciate with, with the slip straw is just It, it, it's like plug and play with all of the standard windows and, and all of the standard framing that we use in this culture, the tricky the tricky part with the windows is, is that like I said, you're framing the slip straw wall out with typically two by fours, which is great, because it's a lot less lumber, right? You know, and it's a lot less expensive, and it's a lot less trees being cut down.
But when you get to the window, you want to do the window frame, not the not the king studs, but the frame itself, you want to do with boards that are the full thickness of the wall, full thickness of the wall, so maybe up to like a two by two by eight or two by eight for the windows. Okay, two by eight or to buy 10 depending on how thick you're going with your wall. The first cabin that I built was two by six. Or it was it was six inches thick, and it was not terribly warm. So I went with I went with eight inches on the addition that I put on this cabin and that was that's definitely better. But it is not white is insulative. Like I would I would think just guessing it's probably like our 12 Okay, it's not as insulative as the you know, I think I think a straw bale wall is our 36 right, I think amazing.
Ethan Waldman 32:25
I just asked Dr. Google real quick. Oh yeah, seems that the R value in one test of straw is 3.4 per inch. So it sounds like you're about about on there a two by four wall would be about our 12
Natalie Bogwalker 32:41
Well, but the wall is actually the two by four is just the frame the wall ends up being eight inches thick. So straw just on its own in a straw bale is more insulative that per inch than it is when you make it into straw clay and that's because you're coating it with that clay slip and your you have to pack it in you have to compact it all in right and so that slip is more of a mass material so that takes away some of the some of the insulation yeah factor and then the packing it in takes away more of the of the insulation factor. And there's another piece to it, they can take away because I did some thermal imaging of my addition, because I'm just dorky like that. And because I have a friend who runs this ecological building center and so I borrowed his thermal imaging camera.
Ethan Waldman 33:40
Good friend to have.
Natalie Bogwalker 33:42
Yes, great friend to have. And it was pretty fascinating because typically straw clay even if you put a bunch of stuff in it to keep this from happening, it always settles a little bit. And then right before you plaster you have to do some like straw, heavy cob at the very top, the take up that space from the settling and once it's dry, it's it's done settling, but it always settles a little bit. And that little area off had definitely a much higher rate of heat transfer than anywhere on the rest of the wall, which totally makes sense then it's just one of the like, better that it's just a tiny bit of copper than the whole wall being. Right. Yeah. So you so you essentially have a thinner, thinner than you if you had built the wall out of cob. It would have been much thicker, but you have this thin, relatively thin strip of cob up at the top that's going to Yes, transfer heat up there.
Ethan Waldman 34:42
Yes, yes. Okay. So what like what would you say is like the best use case for first slip straw like, you know, what's the ideal building size and climate for first slip straw?
Natalie Bogwalker 34:59
Hmm, that's a good question. And I'm going to take us off topic because there's something that I wanted to address that are off topic. Here we go. Um, so one thing that I want to mention is that a lot of people do slip straw where you know, hi said, you want to leave some space between the forms and the two by four, brain. And so that is not something I did with my first slip straw building with my first flip straw building, it was framed out with two by sixes, and I just sucked the forms with by, well, back then it was a drill, not an impact driver. Right up to my, my frame. And the thing about that is then you have a lot of heat transfer through your stud just like with conventional construction, but something that's really cool about the way I did my last project, which I wish this man Brad Merkel, who's a friend of mine, turned me on to which is so great is by leaving that space in between the studs, and your form, which I will get you a drawing of this, that the viewers see it and understand better is that then you do not have the same, the same thermal transfer that you would if your stud goes all the way through the wall, because you're coating your encasing the stud with the insulative material, which I think is a very cool technique and also something that's used with hempcrete.
Ethan Waldman 36:37
Natalie Bogwalker 36:38
Which is another really cool, but much more expensive way to build.
Ethan Waldman 36:43
Awesome. Alright. Well, that's, that's really cool, because we talked about that a lot in conventional tiny house building, you know, creating a thermal break so that you don't get that transfer.
Natalie Bogwalker 36:55
Ethan Waldman 36:56
And it sounds like you essentially are doing the same thing just in a natural building.
Natalie Bogwalker 37:00
Yes. Totally. And without toxic materials and foam, which is like such a has so much embodied energy into it so much.
Ethan Waldman 37:10
Yeah, but is really awesome to use.
Natalie Bogwalker 37:14
But yeah, so anyway, and then the ideal climate for straw clay. So straw clay, I would not use on a mobile tiny, I think it's best to use in a permanent tiny. And that's because just anything that has plaster on it. I mean, honestly, the straw is very strong, and really interlocking, but all the shaking going down the road is just going to wreck havoc, especially on your plaster. Yeah. And so I think it's just not appropriate, even though it might be light enough, okay, it still is still not appropriate. And that goes for most natural building techniques, although you could definitely do. And I have done in our workshops, because we have two tiny houses leave our workshop. He said, we run it and we run it twice a year. So we have four, we crank out four tiny houses a year at this point, which is pretty cool that go to like the recipients are part of the whole process. It's a really beautiful thing, you know, for these recipients to receive them at the end of the classes.
But anyway, back to my point, which is that it makes more sense to do straw clay on a permanent tiny. And with the with the climate, I would say it'd be nice if it was a little drier than it is here in the southern Appalachians, which is basically the entire country except of the US anyway, except for the Olympic Peninsula in Washington State. So somewhere drier than here would be great, which is pretty much everywhere. And I would say that I would not go like I do a lot of gardening. So I don't know how many of you of your listeners are familiar with the USDA hardiness zones, but that's kind of a nice way to talk about it. Yeah. And you can look up your hardiness zone really easily on the internet. So I would use straw clay construction for anything, zone seven or warmer. And I also think that if we're in zone six, it says on the maps that we're in zone seven, but we're not because we're not in the town, and the town is way warmer than the country because of all of the thermal mass in all the roads and buildings.
So anyway, I would use something that's a thermal mass material, if you're in a desert, okay, if you're in a place that has really big temperature fluctuations, like from night to day, like, I think Taos, New Mexico, for example, I'm just gonna, I don't have access to Google as I'm speaking. But I would imagine that they have, at times temperature variations from or gradients from night today that are like 40 to 50 degrees Fahrenheit, of like the difference in the temperature. And for that sort of climate, you want a thermal mass material, because that's going to hold on to a constant temperature, and really take, make it like pleasant inside, whether it is really, really hot out or relatively cold out, it's gonna, like make everything more moderate. Now the insulation is appropriate for places where in the winter, you always want your space to be warmer than it is outside. And in the summer, ideally, your place would be cooler than it is outside or the temperature. But for at least one of the seasons, you want it to be really different temperature from inside to outside rather than just being like, a happy medium between the day and the night.
Ethan Waldman 41:07
Natalie Bogwalker 41:08
And so for anywhere, that is not desert, that's usually the situation. So I would say somewhere zone seven or warmer. That is not a desert.
Ethan Waldman 41:20
Got it. So that's I'm looking, I pulled it up and it looks like we're kind of talking about the the southeast and South southwest, and mud like California and and yeah, Western Oregon and Washington, but then avoid the Olympic Peninsula.
Natalie Bogwalker 41:40
Yes, yes too wet.
Ethan Waldman 41:42
Got it. Got it.
Natalie Bogwalker 41:44
Ethan Waldman 41:45
Totally. Yeah. Yeah. And I would think for a good bit of the Mid Atlantic. Yeah, it would be appropriate to yet zone, you get zone six that works in like New Jersey and the lower half of Pennsylvania and Ohio and West Virginia, and a bunch more.
Natalie Bogwalker 42:04
Ethan Waldman 42:05
Yeah. And if you're more close to the mountain radiating moderating ocean temperatures than let's be honest zones, or who knows when this map is from I'm sure the zones are all one warmer than they were?
Natalie Bogwalker 42:17
Oh, yeah, they totally are totally alright. It's been interesting with our online gardening school, like we've made our own system. Just like basically, the zone just shows you like the coldest temperature possible, it doesn't show the average range. So that's been interesting to, but we're not talking about that right now.
So yeah, straw clay is pretty awesome. And awesome. And happy I'm starting to work with, and I haven't worked with it much, because the materials are harder to come by.
Ethan Waldman 42:50
Okay, so yeah, what what is hempcrete? Because we actually, we had Hijjar Gilbran on the show, who teaches who kind of pioneered and teaches aircrete? Which thing, which I know is something different?
Natalie Bogwalker 43:04
Yes, they suffer from having very similar names. So what is, as is similar in this in this field. And that's I think, largely because there there's a lot of similarities between the techniques, because they're all techniques to make a wall. And naturally built roof systems are a whole nother story, which I could, I could go on for quite some time about and, and do in one of the classes in the online. Dining Out.
So the so hempcrete is very similar to straw clay and the way that it's framed out in the walls and with the types of forms that are used, although there can be different techniques for moving the forms around. But basically hempcrete instead of using straw, you're using hemp hurd. And so that's basically chuncked up hemp stocks, okay? And so there's chunked up, hemp stocks are very cool, because they have a lot of trapped air in them. And when we talk about insulation, that's what we're talking about is fluffy, light materials that have lots of trapped air inside. And the cool thing about the hampered is it's relatively rigid. So it's like, there's a bunch of trapped air, but when you compress it, it's not going to compress.
Because the heavy material that's in from that stock is relatively rigid. And so that is then coated in a special type of line. And so the thing about the lime the lime is the binder that holds everything together.
Ethan Waldman 44:45
Natalie Bogwalker 44:45
and hempcrete was pound I can't remember exactly where I think somewhere in France, from like ancient times, there was hempcrete that was like exposed to the elements and still totally solid like it's been Basically like concrete, like it's amazing material. So, you know, the, what you can do with hempcrete is not limited to building wall forms that are covered by a roof like it is with slip straw. Like, you could have much less of a wall overhang. Like there's a lot of different things like, theoretically, well, I'm not going to get into all the all the all the possibilities, but the thing with it is the binder is a type of lime and so that lime, like any type of quicklime has been heated to a high temperature. So that then when it is brought into contact with water, it um, it then when it dries, it basically goes back into being limestone.
Ethan Waldman 45:47
Natalie Bogwalker 45:48
And so when you mix this hemp hurd, and this very specialized lime, which unfortunately is not manufactured in the United States at this point, which is one of the issues with hempcrete is the availability of these materials, like we have quicklime that I use for lime plaster that I can get really easily but when I talked with this expert on hempcrete, about ordering this stuff for this project that he's going to be teaching here, Tim Callahan, he's just fabulous builder, and designer, he sent me to this company that imports it from Europe. And so when you're looking at embodied energy in the structure, you're not only looking at the amount of fuel that was used to bake that lime, nor are you looking at the amount of carbon that was released into the atmosphere, when that chemical reaction happens to turn that limestone into quicklime. You are also looking at then importing is 80 pound bags of lime from Europe.
Ethan Waldman 46:53
Natalie Bogwalker 46:54
Which is really ridiculous here because if you go over the Tennessee line where I live, there's tons of limestone. So it's it's it's a it's all a really cool technique that all these materials could be available locally, but they currently aren't. And the the equipment and the know how that goes into making this very nice line is something that they just it was it was take some money and time and someone being really dedicated, which I hope one of your listeners decides to dedicate their life to creating local localized lime kilns like there used to be, but right now they there used to be okay, there used to be and actually when I was traveling, I used to live in Spain, and traveling around the mountains in Spain, like there's lime kilns all over the place because they used to, you know, they didn't used to be super highways, then people would bind lime and bake it locally.
But whatever the case is, also the hemp there's some supply issues because while growing hemp is now legal, with a permit in North Carolina, and there's huge hemp fields, and a lot of places. The processing facilities are not everywhere. There is one now near Durham, North Carolina. It's called the Hemp Hill. And they sold out of their hemp hurd almost immediately after the harvest last year. So they still have some available for purchase but it is imported from Europe. Yeah, and, and Tempest texture, which is out west in Idaho. They also have hampered available which I think is actually from East Coast's grown hemp, but to order it, it was going to be $1,000 in shipping, while the product that I was buying for the size of while I'm doing was only $400. $400 that's $1,000 in shipping so one of our students is going to pick up this European hemp hurd from Durham, and I'm just excited that they are growing it locally and processing it locally. And hopefully they get to a scale that can support the need. Yeah. Which is big because it's such a cool material.
Ethan Waldman 49:09
Yeah, it's it seems like it really has a lot of potential as a material.
Natalie Bogwalker 49:15
So it looks like equipment wise this this mixture of the hemp hurd and quick lime has to get kind of sprayed into the wall like what what if the board was poured, okay, it's poured into the wall. So it's a much more wet mixture than the stroke by which the straw clay is like is basically like, you know, straw coated in a very thin like it's like straw coated with salad dressing of a salad dressing. dressing. Yeah, it is. That's how I like to describe it. Yeah, and you kind of like you can toss it like you would toss a salad.
But with the if you're doing it on a large scale. Then there's special types of like Concrete mixers that work really well. So this can be done on a more industrial scale, it can also be done in a more of a home scale, right? And basically, you mix the lime, and then you add in that person. And then you pour this like slurry mixture mixture into the wall.
Ethan Waldman 50:18
Right. So it looks like also that there are people you can pour it into forms and make blocks.
Natalie Bogwalker 50:25
Yes. Yeah, you can make blocks and then you can build with those blocks. Yeah. Which I mean, it's a very cool, it's a very, very cool material. It's still like you need a relatively thick wall, similarly to slip straw so and because I don't think that it really makes sense for a mobile unit even Yeah, to use the hempcrete. I think go if you want to go natural. With a mobile unit, I think going for just a stick frame with hopefully local lumber. And then using a more natural insulation material makes a lot of sense. And there's there's lots of different things available that there's Hempel actually which is a very comparable to fiberglass insulation with its R value.
Ethan Waldman 51:15
Natalie Bogwalker 51:16
And there's also I've used real wool I use that in my cabin, although I'm having some insect issues. Even though it was it was so expensive, but even though it was was impregnated with borax, and they assured me there would be no insect issues. 10 years down the line. I'm I'm having wool moths and I don't like what I'm seeing.
Ethan Waldman 51:40
Yeah. Yeah, very well. So there's rockwool, too. I don't know if you if you like that as a product.
Natalie Bogwalker 51:47
Yeah, I mean, I think it's a fine product. It's a little more industrial, you know, then those other options? And I think a little less renewable.
Ethan Waldman 51:57
Natalie Bogwalker 51:58
But it is as far as toxicity. It's definitely not bad. It's expensive. Yeah, though, because I think largely it cannot compress in the way that fiberglass compresses. So it's really, fiberglass is, you know, the standard insulet insulation material. And nowadays, you know, they have formaldehyde free fiberglass. And what's so great about the fiberglass is that in our modern, you know, day and age of not having vernacular architecture, which is all another story, but is that it, you can compress it. And so the shipping cost is way low, whereas rockwool cannot be compressed. So, you know, all of this hugely fluffy. I mean, if you can imagine all the fluffed up volume of insulation for house like even for a tiny house pretty big. So it gets pretty expensive to ship it around. Got it?
Ethan Waldman 52:55
Natalie Bogwalker 52:55
And that's a big part of its expense.
Ethan Waldman 52:58
Wow. So and you mentioned that you're going to be doing a hempcrete project, and you have an instructor coming to do that. What can you tell me about about the project or about the class?
Natalie Bogwalker 53:10
Yeah, totally. So I like to teach some classes. And if there's ever anything that I think that there's someone more expert than me to teach it. I'm happy to hire that person. So we have this man, Tim Callahan, who's this just wealth of knowledge. Yep. teaching this hempcrete class that is a piece of our tiny house and natural building class for this year. That class, we are offering two this year, both of them filled almost instantly during our new year sale. So there's not there's not spots available. Although, if you get on our waiting list, occasionally a spot will open up. So it's definitely the thing to do. And if people get on our waiting list is also helpful. Because then you find out about the new year sale, and then you can actually get it
Ethan Waldman 54:00
Wow. Yeah, yeah.
Natalie Bogwalker 54:02
So it's, it's just it's such a good class. Surf really good glass, like, you know, it's 10 days long. People get the all of our online materials and lectures ahead of time. So all of the time here is hands on.
Ethan Waldman 54:16
And so that is 10 days of hands on natural building and tiny house construction gets you pretty far with like, you can leave this class and like Actually, no, you can come having done nothing and leave being like yeah, I can build a tiny house.
Natalie Bogwalker 54:34
Yeah, take me a while but I could totally do it.
Ethan Waldman 54:37
Do you get through a whole house in those 10 days are there like multiple houses in different kind of stages of completion that people can work on?
Natalie Bogwalker 54:45
We split the class and we do two belts, we typically do one mobile and one permanent and so the students just have to choose you know which they want to do. And we start with the recipient has to have The floor done. And we do we have another like we teach foundations and floor system, just with with another way like we build a deck or something, you know, there's just like a little bit easier. So that way we have everything staged and ready to go for the build. But the students also get to learn the foundation of our system. And then the class will frame the whole thing. She that and install the doors and windows sometimes get to some of the some of the electrical and insulation and put the roof on. So that's Yeah, we got pretty far. Yeah. And then as far as trim, and interior paneling and siding and stuff that's all covered in the online partner class.
Ethan Waldman 55:49
Natalie Bogwalker 55:49
Ethan Waldman 55:50
Well, I have one great question. These these interviews stream live just into Tiny House Engage and nice. There's a great listener question, which is can bamboo be used with the natural building techniques? And I guess, maybe I'll say could bamboo be used with with slip straw?
Natalie Bogwalker 56:09
Yes, bamboo could be used with straw. The issue is, then how do you attach the roof to the structure. And so the the glory of using lumber, and the lumber does not have to be big. Like we actually in this particular situation, we just ripped rough sawn two by sixes in half. So we're using two by threes. They can be wonky boards like I typically when I'm when I'm talking about tiny house construction, I do not recommend that people use salvage lumber. You know, for their framing, I recommend salvaging all sorts of other things. But the framing lumber typically no because then it just creates all sorts of wonkiness. But when you're doing slip straw, it's totally fine. You can have the wonky looking two by fours you could ever want. Like, it's no problem. But, um, because it all just gets hidden by the wall. And honestly, if there's a little bit of little bit of form to those two by fours, it can create a little bit more of a fun organic coffee looking wall.
Ethan Waldman 57:15
Natalie Bogwalker 57:16
But if you are doing a more conventional frame, it makes it really easy to then put your rafters on and have them have something really strong to sit on. And so I would say yes, it is possible to use bamboo. And it will be this whole nother way of thinking and looking at it that would then look to bamboo construction to see how then they attach a roof.
Ethan Waldman 57:47
Okay, yeah, so you have to figure out your structure of how you're going to make it structurally sound with bamboo. And then you could use the technique.
Natalie Bogwalker 57:55
Yeah, you totally cut ice, you totally could. And I do use it, I use strips of bamboo, about every two feet. In the wall, I drill through the studs, and use strips of bamboo horizontally to kind of help the whole thing not settle as much. It's like bamboo rebar got inside of the sub straw. Now when you do your roof system with slip straw is kind of the same process, you put up your forms and you you pack in the straw. So the roof, the roof is not insulated with straw.
Ethan Waldman 58:30
Natalie Bogwalker 58:31
it's it doesn't really work for roof insulation, we just use, like, whatever you would use for if you're doing a straw bale or a conventional or any sort of roof, we just frame it out with rafters. And then we put some sort of bat in between the rafters typically. And that could be well it could be humble, it could be any number of things, although there's also batch. And thatch is a very exciting place. And it's unfortunately in most of the world. In the last like 40 years. I mean, there's there's traditional thatch in Japan, there's traditional thatch so much in the UK and Ireland and France and all over the world, there's been a thatch.
And it's such a cool material, like if you do it right, with the traditional materials that are used in all these different places they can last like 40 years. And it's totally renewable. You know, it's grass, or grass stalks or different things. And it's also super insulative big because it's grass. And so you know that's a whole nother story that I would love to talk about and and it's very fascinating because the traditional roofing material in Japan is this grass. It's called miscanthus grass, and it is horribly invasive in southern Appalachia.
Last year, where I law and so it's this, it's this really interesting boon. And I've thatched a couple little structures with it. And I have a dream of, of bringing in a Japanese thatcher as an instructor to show us how to properly use that because I mean, I was just playing with it and, and the structure that I built thatched and it had too low of a slope like typically with that Shreeves, you need a very high pitch to be able to make to make it said water properly.
Ethan Waldman 1:00:35
Natalie Bogwalker 1:00:36
And so mine was not a high enough pitch, but it still, you know, the structure lasted and was waterproof for like seven years. And then that particular structure was just kind of this fun, whimsical structure that then got replaced by a much more utilitarian, bigger search later. But um, so I don't know what would have happened after that seven years. But up to that point, it was great. And but it's interesting with the nianthus, you don't actually use the grass, you use the flower stalks of the grass, which are like seven feet tall. They're pretty amazing. But cool. That's a whole nother story. That's a whole nother story.
Ethan Waldman 1:01:16
That's, that's, that's the third. That's the third interview right there.
Natalie Bogwalker 1:01:20
And there you go.
Ethan Waldman 1:01:21
Well, Natalie, I you know, you're just such a wealth of information and your show enthusiasm about it. I feel like we could just talk for hours. But you know, I just thank you so much for being returned guests on the Tiny House Lifestyle Podcast.
Natalie Bogwalker 1:01:35
My pleasure. And thanks so much for, you know, serving all of these people with your resources. And with this podcast, it's just like, I don't know, I just really appreciate everyone who's doing work with empowering people to build their own structures and to live in small structures, like just the environmental repercussions in this culture that's become a culture of like, mcmansions is, like, pretty profound. So I really appreciate your work.
Ethan Waldman 1:02:06
And thanks so much for talking with me. And, and yeah, just working together is really fabulous.
Natalie Bogwalker 1:02:14
Unknown Speaker 1:02:16
Thank you so much to Natalie Bogwalker for being a guest on the show today. You can find the show notes, including all the photos that of things that we discussed at thetinyhouse.net/170. Again, that's that thetinyhouse.net/170. Well, that's all for this week. I'm your host, Ethan Waldman, and I'll be back next week with another episode of the Tiny House Lifestyle Podcast.
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