Natural Building Techniques & Materials

We’ll be learning more about Sigi and the work she does for clients at Down To Earth Design, and what it means to build with natural materials.

This is Mother Earth News.

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[00:01:36] Introducing Sigi Koko and Down to Earth Design

Kenny Coogan: Good day everyone, and we appreciate you for joining us on another exciting Mother Earth News and Friends podcast. I am Kenny Coogan, and joining me today is Sigi Koko, the principal designer at Down to Earth Design.

At Mother Earth News for 50 years and counting, we have been dedicated to conserving our planet’s natural resources, while [00:02:00] helping you conserve your financial resources.

Today we are going to learn about building with natural materials. Sigi Koko founded Down to Earth Design in 1998 to help people achieve their dreams of living in natural, healthy homes. Sigi’s uniquely collaborative design process provides a high level of information and support, encouraging her clients to engage fully throughout the design and construction. She also teaches natural building workshops. Welcome to the program, Sigi.

Sigi Koko: Oh, thanks Kenny. So nice to be here.

Kenny Coogan: Great to see you again. What background did you have when you first founded the company, Down to Earth Design?

Sigi Koko: Hmm. So I have a graduate degree in architecture, so it’s an, um, it’s a professional degree, um, arc.

Uh, and I then had worked for a [00:03:00] construction company doing, um, just conventional housing construction to get some experience building so that I could talk to builders better and know what their job was like a little bit better. And then, um, and then I worked for an architecture company. I have to do sort of an internship, uh, apprenticeship, and I did that as well.

And then, soon as I was done with my apprenticeship, I was outta there.

Kenny Coogan: When I first learned about natural buildings, I’m thinking like the three little pigs, you know,. Like, oh, here’s a building made out of hay that you can live in, but your designs are actually designs and they’re beautiful to look at, in addition to being sustainable, built out of natural things.

So what does it mean when we say “natural buildings”?

Sigi Koko: Oh, that’s such a great question. Um, so this probably means something different to different people. So I’ll give you what my definition is. So to [00:04:00] me, natural building is using the materials that you have available locally, that you have in abundance, that you can harvest without harm, and using those materials to build the most energy efficient building that you can. It doesn’t mean everything is dug out of your yard to build your house, but the goal is, because I think if we strive for absolutes, we, we don’t take any steps towards something because it feels impossible. So, um, the goal is to use as many natural materials, as many materials from nature in our surroundings as possible.

So generally that means, uh, a pallet of generally agricultural fibers. So we’re talking straw, right? So the big straw bales that you see in a field. We’re talking clay from the ground. So clay soils. Uh, stone. And would if it can be respectfully harvested or locally harvested in a [00:05:00] respectful non, non environmentally damaging manner.

Kenny Coogan: So I believe that you live in Pennsylvania, but you’re, do you service all of the U.S. or just the Northeast?

Sigi Koko: Mm, so I, I call it the Mid-Atlantic region. Um, so I have projects anywhere from Vermont to North Carolina. Uh, theoretically I could work anywhere in the U.S. Um, I try to encourage people who are not within driving distance of me to use, to work with someone local.

[00:05:30] What Makes Natural Building Different?

Kenny Coogan: Very good. So my, my real question was, is this style of building popular around the world? Is it only where you can find a natural builder designer? Um, have people been, do, I mean, I imagine people have been doing this for thousands of years because that’s how we initially build houses. But today, is this style popular in certain places?

Sigi Koko: Um, so I, the word, the word popular is…. [00:06:00] there are natural buildings in every state in the entire U.S. except for Delaware. And as far as I know, well certainly every continent except for Antarctica. So there, there are examples of natural buildings everywhere in the world.

70% of the world, it’s population lives in a home that has clay in it, for example, 70%. Some of that is necessity, some of that is, um, tradition, and some of that is in, in the U.S., it’s getting back to something that was there for a really long time. Um, but just as an example. So I would say any, if you live anywhere in the U.S. you could certainly find someone who understands how to design and/or help you build a natural building.

Kenny Coogan: Now, some people might be, you know, listeners might confuse natural buildings with earth ships. Can you talk about [00:07:00] what each of those are and how your designs are different than an earth ship?

Sigi Koko: Yeah. So an earth ship is one very specific design. Um, it was designed by an architect, you know, who basically came up with one design And the what earth ships do really well is they create closed loop systems, right? So they, if you use energy, you create that energy. If you dirty water, you clean that water, right? So, um, there is no way in which the functioning of the building takes from the environment and gives back something worse than it took, right? So clean water and dirty water, right? However, it doesn’t use natural materials to get there. And there is one design option.

Um, so to me, right? There’s, they use a lot of cement. Um, they use a lot of aluminum cans, which in all honesty, if there’s one thing you recycle every single time, it should be an aluminum can. [00:08:00] So the closed loop systems, any building could have closed loop systems. It doesn’t have to be an earth ship in order to create those closed loop systems.

And so to me, I would rather have lots of different building designs. I might be biased on that, but um, lots of different looks, lots of different aesthetics, lots of different functionality. And then have this material palette that can be used to make the building look however you want that’s also then healthy. That’s also has a low carbon footprint, which earth ships don’t have and that are just beautiful homes, right?

Kenny Coogan: Can you talk about how the landscape and the climate influenced your design? And before you say that, I guess, are earth ships mostly in the southwest of the U.S. because it’s that specific design?

Sigi Koko: So they were designed for the Southwest, sort of the high plains in the southwest. They should, as [00:09:00] designed, that is the climate that they should be built in. There are examples of earth ships that are built in four season climates that are uninhabitable because they’re so moldy, right? There’s so much condensation inside of them and there’s mold inside the wall systems and they’re just toxic.

And to me, I, if I’m building something that I’m calling a natural building, I want it to be energy efficient. Great. I want it to close my water loop. I want to clean the water that I use. Great. But I sure as heck also want it to be really healthy, right? So, um, buildings that are made with straw and clay. Yeah. Um, they, they actually clean the air, right? So like the clay has this ability to absorb toxins and, and, um, encapsulate them. Um, so you’re, you’re in this sort of breathing lung building. It’s like you’re, you’re vegetated wall there, right? It’s like something that cleans your air. Why wouldn’t you want that instead?

So [00:10:00] I am not a big proponent. You can tell. I get very animated about it. I’m not a big proponent of taking one design and then putting it everywhere in the world. That’s not, that’s not logical to me. You should be able to look at the building and tell what climate is it in, right? If it has a flat roof, could it be because you’re collecting water? You live in an arid climate and you’re using the roof to collect water. If you have a very steep roof, okay, maybe you get a lot of snow there and you don’t wanna have the snow pile up on your roof, right? You should be able to look at the building and say, oh, that’s a hot climate. Oh, that’s a cold climate. Oh, that’s a four season climate. She must get a lot of rain. If you can’t look at the building and tell where you are in the world, I like, to me, I lose the point.

Kenny Coogan: Makes a lot of sense because it’s um, a pretty big investment time-wise and um, I believe you said financially it’s usually about the same as a traditional modern home. If you’re doing all [00:11:00] that sweat equity, you wanna be able to live in it all the time.

[00:11:04] Siting and Planning a Natural Building

Kenny Coogan: When you’re talking to the clients and they say, hey, we want a natural building, how do you get started on a project? I assume you go to the property, you see the resources that you can work with. And then do you consider the angle of the sun? Do you, what things do you consider?

Sigi Koko: I sort of create this site map where I take a map of their property. I draw on that map when we’re walking the property together. Everything you experience with all your senses. What do you hear, right? If you have a road noise in one direction, maybe you wanna build something so that you protect yourself from the noise of that road. If it’s really windy in one direction, maybe you wanna orient it so that you can plant a row of evergreen trees with low, um, branches like junipers or something so that you block the wind. Definitely the angle of the sun, because that’s [00:12:00] sort of your magic in terms of energy efficiency, because if you face the equator, the sun is high in the sky when it’s hot out, and it’s low in the sky when it’s cold out. And so you can capture the sun in that low angle when it’s cold, when you want the sun, and you can shade yourself from the high sun very easily with just a little bit of a rim on your, on your roof. And so using that, that orientation to the sun is definitely, is definitely a big one.

Um, it might be the slope of the land, right? So if there’s a dramatic slope, you might wanna step down the slope. So there’s all of these different, um, there might be deer paths, there might be, you know, things you see, right? A view that is, oh my gosh, we have to look at that tree, or that stone, or that, whatever, right?

So all of those variables get mapped out on the site, and then you start orienting the spaces with all of those things in mind. So it’s like this gigantic puzzle that you’re [00:13:00] solving.

Kenny Coogan: When I went to Iceland, uh, many years ago, I found many, like traditional natural buildings that were kind of half in mounds or mountains or caves. And then almost everyone had a green, uh, living roof. Do you like to build houses above the land, or do you like ’em halfway receded into, you know, the ground, does that help with insulation or are there problems associated with being, you know, halfway in a cave?

Sigi Koko: Um, yes and yes, and sometimes. Um, um, so I, to me, the, the, whenever the solution is, has everything to do with the aesthetic criteria of the client and the functional criteria of the site, right?

So I wouldn’t say on a flat piece of property, okay, let’s go underground, right? On a hill property, maybe part of [00:14:00] it wants to be underground, right? So in, in Iceland, for example, they have a higher, I believe this is true everywhere in Iceland. Um, If this is wrong, someone can correct me. They have a higher ground temperature than we do for one, even if they didn’t everywhere in the world with the exceptions of where you have these, um, where you have thermal activity in the ground, the ground temperature’s around 57 degrees, so the ground temperature doesn’t change and the outside temperature does this day and night. It’s going up and down, up and down, up and down.

You can create a consistent temperature inside a building by, um, using the thermal mass of the earth to create that constant.

But the problems are, there’s moisture in the ground, so how do you get, how do you keep that moisture out? And usually that’s not a natural solution. You can’t put windows if it’s underground there. So it’s hard to balance your daylight. [00:15:00] It’s hard to balance, it’s hard to get good airflow if you can’t get a window on the other side. So there’s, there’s pros and cons for sure to building underground. So, but I wouldn’t say like, you should always do X. It’s just, it depends, but, um, it’s certainly something you can have in your wheelhouse is to connect to that mass of the earth.

Kenny Coogan: Yeah. Having that volcanic activity underground heating up the ground is probably why they traditionally have done that. That’s a good point.

[00:15:28] Building Materials in Natural Building

Kenny Coogan: So I know you mentioned clay, and then I wanna talk about some other common building materials. So, can you tell us what cob is and what a straw ba- I know what a straw bale is. But then can you tell us what hempcrete is and how those three uh, items are the same? Are they different? And um, I just learned yesterday that hempcrete is one word. So can you tell us what cob, straw bale, and hempcrete are, [00:16:00] and how would you use them?

Sigi Koko: Absolutely. So cob is the same material as adobe, which is a combination of clay, which is sticky, sand, which is um, like a tiny, tiny stone, right? So it’s very strong to push on, and then, uh, straw fiber or some kind of agricultural or natural fiber. And the fiber gives it tensile strength. So you have fiber that’s tensile that can pull, you have sand that can push, so it’s strong in pulling and pushing. And it has clay that sticks everything together like glue.

And the difference between cob and adobe is that adobe are formed into bricks and then dried in the sun, and cob is built monolithically in place. So that’s literally the only difference. Um, different parts of the world actually have different terms for cob. “Cob” is the British, the UK term.

Straw bale is [00:17:00] basically you’re building a masonry house, but instead of bricks or concrete blocks, you’re using big fuzzy straw bales. But otherwise, same idea. You lay one row, you put the next one offset so that they interlock, you pin them together, you plaster both sides.

Kenny Coogan: And are you pouring anything over the straw bale or it’s like just….

Sigi Koko: You’re plastering it. Yeah. In the, when you’re stacking, there’s only straw. When you’re done stacking and you have a wall, then you put usually plaster on both sides. You can also put siding on the outside if you want siding.

And then hempcrete is a combination of, it sounds like it’s concrete, but it’s not. It’s hemp hurd fiber. So hemp hurd is the woody stock part of a hemp plant, and they chop it up so it looks like little twigs. And they’re hollowish, and you coat that with lime. So a particular type of lime called, um, hydraulic lime. And [00:18:00] all that means is it’s a lime that is calcium carbonate, which is what limestone is, what marble is, right? And it reacts in two ways to harden into, um, like a mortar almost. It reacts with CO2, so it pulls CO2 out of the air into the lime. And it also, because it’s hydraulic, it reacts with water. So as soon as you start mixing it and you add water, um, just like cement, when you add water, it starts to harden. Same idea. So some of it hardens with the water, some of it hardens over time by pulling CO2 in. And basically you have this hemp, you coat it in the lime, so it looks almost like a really gross rice crispy treat.

And then you infill a wall. It’s not structural straw. Straw bale can be either structural or infill. Hempcrete has to be infill, so it needs some other structural system. You need a cavity to put the hempcrete in.

Straw bale and hempcrete are insulation materials. That means they slow the flow of [00:19:00] heat through the wall, whether it’s you’re warming the inside space and it’s winter outside and you’re trying to keep the heat in instead of having it travel out; or where you are, it’s hot outside, maybe not today, but hot outside, and you’re trying to stay cool inside. You keep that heat from coming in. Um, so either way, an insulating material blocks that thermal flow. The more insulation you have, the more you block that flow from ever entering.

Cob is what’s called a mass material and a thermal mass. Instead of being a block to energy transfer, it has conductance. It can, it can allow heat energy to flow through it, but it flows through and gets stored in the mass, like a battery.

So if you’ve ever had aluminum foil in the oven, right, and the oven could be 400 degrees, and you pull it out and you can touch the aluminum foil almost immediately, it’s because the aluminum foil conducts that heat energy [00:20:00] so quickly that the heat leaves and you can touch it. If that were a mass, like a stone and you stick it in the oven, it would stay warm for a really long time when you pull it outta the oven.

And that’s the property of thermal mass. It’s like this battery for heat energy. So it’s completely different kind of material than insulation. And when you use them in combination, so an insulating material outside, so create a bubble between you and outside, and then put lots of mass materials like cob, like thick plasters, like adobe, like rammed earth inside, then you create the most energy efficient building that you can.

[00:20:38] Do Natural Building Materials Last?

Kenny Coogan: Okay, I am, in my mind I like adobe, cob, and hempcrete, but I still need you to sell me on the straw bale. How long do these houses last? In my mind, I have the two walls with the straw bale in the middle, but I envision the straw decaying or just breaking down and [00:21:00] maybe mold or my allergies. So how long does it last, the straw bale specifically?

Sigi Koko: So as an example, the very first straw bale buildings were built in the 1800s, 1880s. When the straw, the bailing machine was invented. They very quickly figured out that the barn where the animals were was warmer than the house and they started building. In Nebraska where there weren’t a lot of trees, they started building with straw bales. And some of those original buildings are still standing today. The oldest building in a humid climate is in Alabama. It was built in the 1930s, also still standing today. None of them have mold problems. So let me explain why.

Any biodegradable material like wood, which we build with all the time. So wood and straw are actually very, very similar materials. It’s just the shape . It’s literally if you took wood and you made straws out of it, you would have exactly the same thing as what’s in a straw bale.

And any [00:22:00] biodegradable material needs moisture in order to decompose, and mold also needs moisture in order to bloom. So there are mold spores everywhere, right? Everywhere. Right here in this room right now, there’s mold spores. In your room. I’m sorry to tell you, there’s mold spores. But they need both the microbes that cause decomposition and mold spores need 18%, consistently 18% moisture content in order to flourish.

And so if you keep your wall dry, which kind of a goal in a building, generally. If you keep the walls dry, it will last forever. Just like wood, right? If you can build with wood, you can build with straw, it’s literally the same material. It’s just shaped differently. Um, and we build with wood all the time. We don’t ever ask that question. And yes, there are examples of moldy wood buildings, but it’s not because of the wood, it’s because of how the wall was constructed. And there’s a leak somewhere and there’s [00:23:00] condensation inside and it’s not breathable.

So if you, if you take a, that principle, I want, I want my wall to stay dry. Well, how do you do that? There’s two ways that moisture can get inside of a building. There’s literally liquid water. And then there’s humidity. So liquid water, rain, and a burst pipe. That’s the two ways liquid water’s getting in there.

So rain is easy. Get the bales up off the ground so that where the rain splashes on the ground can’t wet the bales the same place every single time. And give yourself a nice hat on your building. Nice deep roof overhang so that you’re taking the water off the roof and taking it away from your wall. And then I like to create redundancy at the top of the wall so that there’s two ways for water to go to the side of the bale instead of inside the bale. So just in case there’s a roof leak someday, which happens, it can’t drip inside the wall and you don’t know it’s there until it’s too late. [00:24:00]

And then the second would be pipes. And the simple rule there is don’t put pipes in outside walls, period. No matter what you’re building with, don’t put pipes in outside walls. It’s the dumbest place to put a pipe. And that one’s easy. Um, and has nothing to do with the straw bale. It’s just how you design where the plumbing goes. So that’s liquid water.

And then, uh, humidity. If humidity is only ever stays in the air, right? Like it’s, there’s humidity in the air right now, but I, it’s not a problem. It’s not causing those mold spores bloom, it’s just there. It’s only a problem if it can hit something cold and condense. Now it’s a liquid. Now it can build up over time and cause that wall to get wetter and wetter and wetter and wetter.

So the way that you keep humidity from condensing inside is also two strategies. One, put vapor permeable. It’s also called breathable, but it’s a, it’s a terrible term. Vapor permeable materials on all sides of the wall. And all that means is that [00:25:00] humidity can go through and exit in either direction freely. So you’re not blocking that humidity from transferring through the wall. And now it can’t build up because it can always have an exit.

And the second is eliminate cold surfaces inside your wall. So no metal. Um, that’s the main one really, actually, no metal inside the wall. Because metal, like if you, metal stone would be another one. If you go outside when it’s cool and you touch a piece of wood, it doesn’t feel freezing cold. And on that same day, if you touch a stone or you touch a piece of metal, it’s freezing cold. Well, if I’m humid air, right, if I’m humidity in the air and I see that piece of wood and it’s not really cold, okay, carry on. If I see that cold piece of stone or cold metal, I hit the metal and I turn into liquid on the metal, right?

So like. [00:26:00] When you have a glass of ice water, ice tea, in the summertime when it’s really, really humid and you put it down and water forms on the outside, you don’t want that happening in your wall. And so that’s it. That’s, it’s that simple. And, and really those principles should hold for every single wall system, even conventional construction. They should be breathable finishes and no plumbing and get the bottom up off the ground and put a good roof overhang and eliminate condensation points. And all buildings would be built better if we did that.

[00:26:33] Maintaining Natural Buildings

Kenny Coogan: When we talk about natural buildings, what is their maintenance compared to the modern construction? What, what was the term that you used for?

Sigi Koko: Conventional.

Kenny Coogan: Conventional, yeah. Is, um, I think I’m supposed to be getting a new roof every 15 to 20 years and, you know, I have to maybe hose off the side for algae or, you know, clean the [00:27:00] gutters and stuff like that. So how does the maintenance compare for a natural building?

Sigi Koko: I mean, really like the, the roof system is often conventional. Um, like if you have a metal roof, it has the same warranty as any metal roof on a conventional building. The difference there would be if you have a living roof, which is basically like your plant wall, but on top of the roof. Um, and those have very low maintenance, basically weeding it until the plants can take off, and then they’re usually self-sufficient after that.

There’s really not a lot of maintenance with regard to the material. So what you’re switching out might be some interior walls. So maybe you replace a stud and drywall wall with cob or adobe or rammed earth so that you get that mass inside. I mean, it’s a clay wall like, and nothing’s gonna happen to it. You could drive a truck into it and it’s still gonna be there, and the truck’s gonna be at the, so there’s really not a lot of maintenance there.

And same with straw bale or hempcrete. They’re just inside [00:28:00] your wall. They’re insulation materials. There’s, you don’t have to maintain your insulation materials. It’s really about the finishes then. And your finishes that might be different are on the exterior commonly. I would say you can put siding on any of those. Often it’s a lime plaster, which again is, um, comes from calcium carbonate, which is limestone. Um, it’s heated and then it turns into this, um, calcium oxide and calcium hydroxide, and then it can carbonize and turn into stone. Like basically it’s a plaster that turns into stone on your wall, but that’s still breathable, unlike cement. So think of it that way. Um, it’s sort of like a stucco that’s made from natural materials. And that would be the same kind of maintenance as any, if there’s cracks, you might have to fix the cracks. That said, I’ve been doing this for 25 years and I’ve had one client ever do anything to the exterior ever. That’s probably close to 50 projects. And one person has dealt with their [00:29:00] exterior finished plaster.

And then inside you’re often using either lime plasters or clay plasters and clay plasters are essentially made from clay soils or pottery clay. They can be pigmented. This wall behind me is a clay plaster wall, and they’re also extremely durable.

But worst case scenario, you know, you get a kid who’s chipping away your wall or something. It would take, it takes a lot to chip into it, but it has happened. Then you patch it. So for example, if I have a client who does a pigmented wall, like this is a very specific recipe to get this color. Then we take some of the extra plaster and we make little cookies and we let them dry. And then you put them in a container and you label the container with what room and what surface those cookies are in. And then if you have a hole, you have exactly the plaster that you can just re-wet and fill the hole, right? It’s not complicated. It’s very, very simple.

There’s less maintenance with the [00:30:00] natural building generally, because it’s a higher quality construction.

Kenny Coogan: Very good. We’re gonna take a quick break in our conversation to hear a word from our sponsor, and when we return, we will learn how people can get started with their own natural buildings.

[00:30:15] MOTHER EARTH NEWS Fair House Ad:

John Moore: Have you ever wanted to meet our podcast presenters in person or take workshops from them? You can by going to one of our many Mother Earth News Fairs each year. You can take hands-on workshops, attend information filled presentations, and shop from our many vendors specializing in DIY ideas, homesteading, and natural health.

Our 2023 fair schedule includes fairs in Kansas, Pennsylvania, and Wisconsin. Learn more about all our fairs by going to www.MotherEarthNewsFair.com. Use the code FAIRGUEST for $5 off a checkout. Whichever fair you choose to join us at, we’re looking forward to seeing you there. [00:31:00] Come visit your Mother at the 2023 Mother Earth News Fairs.

And now back to our episode with Sigi Koko…

[00:31:08] Popularity of Natural Building Techniques

Kenny Coogan: …the principal designer at Down to Earth Design. So before we get into how, uh, our listeners can build, do you see this, uh, natural building trend becoming more popular? Or are people maybe since COVID, are people flocking to this design more?

Sigi Koko: I mean, what I would say is I’m in a little bubble, so the only people who reach out to me are people who wanna build this way. So in my world, everyone wants to build this way.

Kenny Coogan: So are, are you busier now than 25 years ago?

Sigi Koko: Yeah. Yeah.

So my first project was a two year project where I co-designed it and then helped construct it. So one project, two years. The second project, one project one year. And then from there forward it was between two and three, [00:32:00] maybe up to five projects a year, and right now I have 11 projects that I’m working on.

It went from three to 11 since COVID. And I, I think it was just people sitting in their space for that long and looking around going, oh, maybe this could be different. Or, oh, it would be really nice to have a bigger office, you know, whatever. Or a beautiful green wall on my, I think that’s part of why. I don’t honestly know why. I don’t ask people I should ask that. That would be good.

But yeah, I, I would say that the biggest thing I notice actually is that when I talk to people, most people have at least some familiarity or some connection besides the three little pigs of what I’m talking about. Oh, I saw that on Grand Designs or yeah, I read about that in MOTHER EARTH NEWS or, it’s right, it’s, there’s other people have heard of it before and that even 10 years ago, that was not the case.

Kenny Coogan: Very good. I see. Um, [00:33:00] since COVID, I think people are just reassessing their lives. I know the house plant business industry has exploded because people are like, well, I’m at home. I need to be looking at pretty things. And they’re probably, you know, just reassessing money, the human connection, things like that.

[00:33:15] Getting Started with Natural Building Techniques and Materials

Kenny Coogan: So I know you’re in the mid-Atlantic and let’s say somebody wants to build a natural building, we’re gonna get to the DIY at the end. But let’s say somebody wants to consult with somebody. How would you recommend finding a natural building designer assistant, or, you know, who can they look for?

Sigi Koko: In this region or anywhere in the U.S?

Kenny Coogan: Yeah, anywhere in North America. Is there a association? Is there, uh, a guild, is there a….

Sigi Koko: There’s some. So like natural builders are not very organized. I can’t explain it. In California there’s CASBA, California Straw Buidling Association. [00:34:00] In Colorado, there’s a similar one, in Arizona there’s one. There’s, so there’s various associations of natural builders or natural professionals. Natural building professionals, let’s say. They could be builders, they could be architects, they could be just straw bale or just cob, or just plasters, whatever. So they’re sporadic around the U.S. In Canada, and I don’t, I don’t know, in Canada, I feel like there’s also in Canada. There used to be a great website that has been offline, but they say they’re gonna go back online. But that’s not a good resource anymore.

Bottom line is that piece is challenging. So you have to use Google and you have to be smart about what you put into Google. So I would put your state, I would put the word natural building, and I would put the type of professional you’re looking for. Are you looking for a builder? Are you looking for an architect? Are you looking for a store? So put in the specific search terms that you’re looking for and see what comes up.

There is a [00:35:00] website, I think it is www.NaturalHomes.org. I’m almost a hundred percent sure, and they, it’s worldwide, but they have a searchable database. People have to know to put themselves on that database. So it’s not by no means complete. I put myself in that database, right? So you can search by region and and professional. So what are you looking for? If you’re a natural builder and you’re listening, go there and put yourself on that database.

[00:35:25] Legality of Natural Building: Zoning, Permits, Insurance, and More

Kenny Coogan: That’s a great tip. Now, are you legally allowed to build home dwellings out of natural materials in every state? Because I’m assuming listeners are thinking, will insurance companies cover my hempcrete homes?

Sigi Koko: Yes. Yeah, so there’s a couple different pieces. So there’s getting a building permit, there’s getting insurance, and there’s getting a loan. So I’ll just, I’ll, I’ll address the building permit the most and then touch on the others.

So, first of all, zoning tells you what you can build where. So if you live somewhere with a hou uh, homeowner’s [00:36:00] organization, uh, housing association, what are they called?

Kenny Coogan: HOA.

Sigi Koko: Homeowner’s Association. You may not be able to build naturally because that neighborhood has decided how you build, right?

That has nothing to do with natural building. It has nothing to do with the government. It has nothing to do with building permits. Zoning tells you what you can build where, but not how you build it. So can I build a house or a factory? How big must it be or can it be no bigger than, right? So those kinds of parameters.

A building permit tells you how you build it in order to ensure that the building is durable. It’s not gonna fall in on your head. It’s safe in a fire. You’re not gonna just burn up. You can get out. The building permit, every single building code in the entire U.S. begins with a paragraph called “alternative materials and methods.” And that paragraph, paraphrasing, states, if you are going to build in a manner that isn’t specifically outlined in this building [00:37:00] code, you can do that as long as you demonstrate that you are complying with the intention of the code.

For example, fire safety. There might be, how many hours does your wall need to be able to stand up in a fire before collapsing? Depends what you’re building. Maybe it’s half hour, maybe it’s an hour, maybe it’s two hour. So the building code will say if you’re using conventional materials, it tells you how to get there. This and this and this and you’re good. If you’re using a material that’s not specified in the code, like straw bales, you just have to show that it will meet that fire rating. And that’s done with third party testing. So it’s called an ASTM test. Those tests are available for free online as PDF files. So you can search “ASTM” and “straw bale,” for example, and you will get the different ASTM tests for straw bale that demonstrate hurricane safety, fire safety, smoke development rating, that you have adequate [00:38:00] insulation value, right? There’s a minimum insulation value everywhere in the U.S. So showing that you meet that.

All of those things, somebody already tested ’em, they paid for that testing, they put it out there for free. You bring that test to your permit office, you demonstrate that your material meets their standard. Done. That’s it. And that has always been the case.

There happens to also be organizations that are working to put different natural building materials specifically in the building code. Adobe has always been in our building code because we have this tradition of adobe in the U.S. And so for example, when I use cob, which again is the same material as adobe, I label it “sculptural adobe.” And the reason is, if I’m a permit official and I’m reviewing drawings, the word “adobe” means something to me in the code. “Cob” means corn on the cob. That’s not a building material. So part of that is then using words that are gonna trigger an understanding as opposed to a question.

So the permit [00:39:00] part is really, really, really simple. You just have to know. You have to know that piece, that it’s allowed. You just have to, it’s on you to show that it meets the code.

In terms of insurance and financing, every single state in the U.S., again except for Delaware, have examples of natural buildings that have gotten both homeowners insurance and financing, every single state. If you are having trouble getting either, if you, again use Google, type in your state, type in “straw bale building” or “straw bale house” or something. Find who that is that has one and call them. Who’d you use? There used to, again, there used to be a database online that is currently offline and it listed homes throughout the U.S. by state. It listed insurance companies that had insured natural homes, and it listed finance, you know, banks that had financed natural homes. But [00:40:00] that database is offline.

The other advice on both of those is, when you’re having a conversation with a bank, for example, you are super excited that you are building with straw bale or hempcrete or whatever you’re doing, right? You’re whoa! So, but don’t run into the bank and go “I’m building with straw bale! Will you finance my house!?” They don’t know what you’re talking about. They’re not excited like you are. You just freak them out and they’re gonna say no before you have any chance to explain what’s going on. So go into the bank and tell them the minimum. “I’m building a home. What do you need to know?” And then be honest. Everything they ask you, be honest. If it comes up, what are you insulating your walls with? Answer the question. Explain that it is a hundred percent code compliant in terms of safety and durability. And sometimes what they want is an example in your area that’s similar. And so that might be the tricky, tricky bit. But again, use Google to find something similar.

[00:41:00] Natural Building Material Options: Foundations

[00:41:00]

Kenny Coogan: So for the rest of the podcast, I wanna kind of go from the ground up and just, maybe you could list some examples of the materials that you use. So what do you like to use to build foundations out of?

Sigi Koko: Ah, it’s an easy one. Uh, my favorite foundation is called a rubble trench foundation. It was Frank Lloyd Wright’s favorite foundation, if anyone’s asking. And it’s basically you, you dig a trench under the structural perimeter of your building. You line it with something called a filter fabric, which just prevents small particles from coming into the trench from the soil. You fill it with gravel, like the same gravel you would put in your driveway. So fairly large gravel. You tamp it so that the gravel just locks, and then you put a very small amount of concrete. You could also do stone, but that requires a higher skill level, but a very small amount of concrete on the top.

So instead of digging all the way down to frost and using a lot of concrete, [00:42:00] you dig down to frost and use gravel, and then a little bit of concrete. So depending where you are, like where you are in Florida, you might use half the concrete as normal. Where we are, it’s about 25% the concrete as normal. If I go up to Vermont, it’s like 15% of the concrete that they would normally use.

So the issue with concrete is that cement is the largest CO2 producer of any building material. It produces more CO2 than cement in the production. Eliminating cement and using it only intentionally is fantastic. So that’s my favorite by far. I think every building, almost every building, that’s all we use.

[00:42:39] How Big Can You Make a Natural Building?

Kenny Coogan: All right, before we start building up, what is the biggest, uh, house size can you build, using natural buildings? Are you building, uh, one story homes? Can you build a three story home?

Sigi Koko: Yeah, you could. There’s no, there’s no restriction. If you’re using the bales as structural blocks, there’s [00:43:00] lots of restrictions. Um, there’s a height limit, there’s a length of wall limit. But if you’re infilling within some other structural system, sky’s the limit.

One building I did was it’s a 8,000 square foot warehouse for wine, and so it needs to stay cool even in the summer, and it does that with the equivalent of an air conditioner that you would use for an apartment. But it’s 8,000 square feet, 15 feet tall.

[00:43:27] Who’s Building Your Natural Building?

Kenny Coogan: Is it possible to find, uh, people to contract out this work? How many people are involved in, uh, building a natural building? I, I, in my mind, I’m assuming you’re finding friends and you’re doing it with the designer.

Sigi Koko: So I would say there’s three paradigms that I usually have in terms of how it gets built.

I would say this is the trickiest biscuit. Are biscuits tricky? This is the most challenging piece. The [00:44:00] way that I work is I will teach whoever’s going to be in charge of the natural building pieces, I will come and teach that. So that could be a builder. Like I come and train a construction crew. It can be any construction crew. I don’t care who they are, I can train them. Or it can be friends and family or a paid workshop. Like you hold a class and your home is the classroom. And what the class does is build your walls.

But most architects don’t teach how to build the building, right? They do drawings and then it says stud wall. And every builder knows what that means. And so that, that, that’s the hardest part, is that you label it straw bale wall. Okay? You now need someone who knows what straw bale wall means, and either that has to be the person who designed it, or you need to find someone who could come and teach you, or you go take a class and you learn and come back or something. So that, that’s the hardest part.

Um, but the, the three paradigms would be a hundred percent built with a [00:45:00] construction crew, in which case you either need a trained construction crew or someone needs to train them as they go; you have a construction crew do everything conventional, either do workshops or sweat equity to do the natural building components; and then there’s just owner builder. I would say 10% of the projects I have are just people who have never built anything before and they build their home.

Kenny Coogan: While we’re maybe not talking about natural materials, I’m, I’m guessing that we can, um, hire an electrician and a plumber to just build within the natural buildings?

Sigi Koko: Yeah. Yeah. Almost everything is conventional, really. Right? So why the roof stands up is a convention, that’s conventional. We’re not reinventing that wheel. How the wires go in. We’re not reinventing the wheel. The only difference is that it doesn’t have to get snaked through the studs. It can just be on the face of the bales. So it goes in faster. But you know, and the plumbing’s totally conventional cuz it’s not an [00:46:00] outside walls. Right.

[00:46:01] Natural Building Material Options: Interior Walls

Kenny Coogan: All right. So we have the foundation, and then we kind of already talked about the walls. What about the interior walls? Is there any materials that you use more often than others?

Sigi Koko: Um, I would say there’s sort of three tiers.

I try to include at least one thermal mass wall. Usually that’s clay. So it could be rammed earth, which is just clay and sand tamped until you physically turn it into stone. It could be cob again, which is the sculpted adobe. It could be adobe. It could be stone. So some kind of mass wall inside. And what that does is it helps regulate the temperature so that you don’t get big temperature swings inside. Cuz it’s that big battery. So that’s number one.

Number two is you could have all of the interior walls could be completely conventional. They could be studs and drywall. That’s fair.

And three would be some hybrid. [00:47:00] For example, the wall behind me is a stud wall. But it has lath on it. So like old lath and plaster homes. And then it has clay plaster on the lath.

And so you’re building the wall conventionally, but you’re finishing it in a way that actually we used to do, but we don’t do anymore.

And then for sculpted bits, like over here, that is wattle and daub, which is the original lath and plaster, which is just woven. It’s uh, like there’s vertical pieces and then you weave through it. In this case, we took invasive vines out of our forest and wove them through the verticals, and then again, just smear clay on it and then plaster it.

Kenny Coogan: I like that idea. Florida is known for our invasive plants and animals.

[00:47:49] Natural Building Options: Roofs

Kenny Coogan: So in the MOTHER EARTH NEWS, uh, December 2022 and January 2023 issue, there was an article on huts. What I wanna [00:48:00] ask you is, what roof materials do you like to build with? Because in this article they said they love their hut except for the days that it rains. Cuz it sounds like you’re in a monsoon because the raindrops are dinging off the metal roof. I know we’re talking about natural buildings, but you said, you know, you could build the roof out of anything.

So what do you like to use, or what or what do you find that you use more often than not?

Sigi Koko: There’s a few that I use often. So one is, um, it’s called a living roof or a green roof. And it’s basically a flat-ish roof. So 30 degrees or flatter. It’s plants on top of the roof. And here in every case, whenever you’re talking about roofing, you’re talking about what is the surface that actually keeps water out of your house. It never replaces insulation. You still always, always, always need insulation somewhere above you, cuz 60% of heat gain in summer and [00:49:00] 60% of heat loss is up.

So living roof, which would be plants. If you’re collecting water, I don’t use a living roof because it gets too much organic matter in the water and it gets stinky. So if you’re collecting water, I like to use metal for its durability. Or in Pennsylvania we have a lot of slate and we have a, have a lot of barns that are falling , falling down that have slate roofs. So you can get basically salvage slate from something that came down. So that’s one of my absolute favorites is to use slate. Uh, you have to make sure that the load of the building can handle the heaviness of the stone. Very important.

What else do I use? I think those are my top three. Yeah. Plants, metal slate.

[00:49:47] Health Benefits of Natural Building Techniques

Kenny Coogan: Very good. Okay, so your finished buildings are energy efficient, natural, and healthy, and there’s like a low impact and they’re space efficient.

So can you just talk a little [00:50:00] bit more about how you accomplish those goals? I think we talked about how it’s ener, energy efficient because you have the insulation working both ways. And then of course it’s natural because we’re using natural materials. But can we you maybe talk a little bit more about the health aspect?

Sigi Koko: Yeah, so I would say there’s um, a couple different components that feed into health. So the one we think about the most is the material toxicity. When you’re using materials from nature in general, you’re using materials that don’t off gas nastiness into your space cuz no one’s sprayed it with chemicals, no one’s dumped it in chemicals to keep bugs out, right? It’s just from nature in your house. So we’re talking clay, we’re talking natural wood, we’re talking natural sealers that are all durable and beautiful and can be really, really tactile.

So part of it then is also looking at the other [00:51:00] materials besides what goes into the walls. So cabinets, for example. Um, specifying cabinets that are low or zero formaldehyde. Eliminating, um, particle board completely because it has a lot of formaldehyde. Formaldehyde is a carcinogen. Minimizing the use of plywood. So you can use solid wood there. We used to build long before we knew how to make plywood. So that means there’s a way to do it, and it doesn’t always mean more cost.

Like a year ago when there was a big spike in building material costs, wood subflooring, natural wood subflooring, solid wood subflooring was cheaper than plywood, as an example. So that’s, you know, you have to kind of be aware of all of the other materials in there.

And then the last piece of toxicity in terms of what’s in your air that you breathe has to do with cleaning materials, which a lot of people don’t think about. So I educate my clients on how to clean. You can clean your whole house with vinegar, baking soda, [00:52:00] uh, lemon peel, like things that are not toxic. Murphy’s oil soap, I love. You don’t need to use bleach, you don’t need to use nasty nasties.

And cleaning products are not regulated in terms of what they have. So people think, oh, if I can buy it, it must be safe. Nope, not at all. That’s that piece. Some of it has to do with how you’re building. Some of it has to do with educating yourself.

The other piece in terms of health in a space is natural daylighting and what your heating system is and what your cooling system is. For example, natural daylighting means if you put windows on two sides of any room that you’re gonna occupy, so besides like a bathroom or a closet, right? If you put windows on two sides, then you get balanced light. You get light coming from one direction, you get light coming from the other, and you don’t get these harsh lines between light and shadow. That’s called glare. So your space is brighter and [00:53:00] less glare. We are solar powered, so more daylighting is fabulous. And bonus, it means you don’t have to turn an electrical light on, which means you also saved energy. So big bonus.

The other piece of having windows on two sides of a space is that if you open them, you will automatically create a pressure change in your space that will cause airflow. If you only have one window, you can’t naturally create airflow. If you have two windows, you can create airflow. Um, so, so there’s all these other pieces. Yeah. In terms of healthy, healthy space and how it feels to a person.

When I take people who have never been inside a natural home and I give them a tour, they step inside the space and you can audibly hear people go [takes a deep breath] audibly. Right. Babies, I’ve seen, like, I had a woman who was standing there with her baby next to a wall, and the baby was just like [00:54:00] petting the wall. I had a sister who had a store and the changing room was sculpted out of cob, and she said kids would run in the store or would come in the store and they’d be like, I have to go shopping with mom. And they’d look up and they’d see that wall and they would sprint to the back and hug the wall. So there’s something about also just the feeling of these spaces that creates just peace.

Kenny Coogan: So I’m really big into the house plant industry because I have a nursery. And what I noticed is that homes that have been, that are being built with the modern style, conventional style in the past, like five to seven years, their kitchens are like dead center of the house. And there’s no windows and there’s no light, there’s no natural light. So people say, oh, I want a house plant. And they go, I’m gonna put it in my kitchen, or I’m gonna put it in my bedroom. And then I ask them how much light they get and they go, oh, there’s no light in there. So they’re, you know, only relying on, uh, fluorescent lights or artificial light.[00:55:00]

I just realized like five minutes ago, the reason why these new houses probably don’t have any windows is because their little, uh, McMansions are probably right on top of each other and they don’t wanna be looking into their neighbor’s house. Yeah. It’s sad when houses don’t have windows.

Sigi Koko: We have in this country a disconnect between, for most housing stock, between the person who’s gonna live there and the person who makes decisions about design and construction. They’re not usually the same person.

I work only with clients who make all the decisions about their space. That is not most people. So if I’m a builder, what is my goal? Probably in high profit. If you go through a housing development, it is shocking to me how many housing developments you can go the, the two walls that face each other. Zero windows. Not one window. That means every room has windows only on one side, and it means the middle has no light. [00:56:00] But why? Because windows are cost the most and they take time to put in. So every time you put a window, it’s cost them money. So they don’t, they’re not doing that. And they’re not gonna insulate to the highest degree possible because they’re not paying any energy bill ever. You are. And so they’ve made all these decisions and then they sell you on it by, oh, but there’s two sinks in the bathroom. You know, like, cool. But my energy bill is out the roof. Literally. I, to me that’s, that’s the issue is that most of us live in homes that were designed by someone who’s motivated by profit and not lifestyle.

And if we had real say we, we wouldn’t prioritize, well, maybe some people would prioritize two sinks in the bathroom, but we would prioritize energy efficiency, health, quality of the space. Most people, that’s what they want.

[00:56:52] Space Efficiency in Natural Building

Kenny Coogan: Exactly. On your website, I was listing the things that your finished buildings, you know, have and that you’re promoting.

And [00:57:00] one of them is the space efficiency. And we were just talking about the two sinks. And so can you just talk, I guess it’s probably probably less natural building and more your style, but can you just talk about how you create spaces that are more efficient?

Sigi Koko: Hmm.

Kenny Coogan: Or, or what does that even mean?

Sigi Koko: Um, yeah, so, um, I mean, in short, it’s building the smallest space that accomplishes whatever the goals are. Each family might have different goals, right? So a couple with no kids has a different size goal than a couple with six kids. If you work at home, you have different size requirements. And if you don’t work at home, you know, what size is appropriate for any given family is gonna depend on that family. But then build the smallest thing, like don’t build big just cuz you can. Build the smallest thing that accomplishes what the goals were.

I mean, one is just knowing [00:58:00] what feels good in a space. So there’s this whole psychology of building. So for example, I was in someone’s house once and they had this very grand kitchen and it was sort of a U-shape with this big island. And the island was 12 feet long. And when you were in that kitchen, you just constantly felt like you were walking around this massive elephant. Okay. So it looks great in a, in a brochure if you’re trying to sell your home. But it’s annoying to cook in there even though it’s a huge kitchen with lots of cabinets and lots of counter space. It was totally annoying.

What is the space between counters that feels ample for two people if two people are cooking? Um, but not so big that you’re feel like you’re constantly, you know, those kinds of things. And then, uh, looking at every opportunity for storage. I’m a big fan of store things where they’re used because you can always find a little storage tuck away.

One of the benefits of straw bale walls is they’re so [00:59:00] deep. You can sometimes use the area under a windowsill to create free storage, um, for example. But, uh, yeah, under stairs, I’m a big fan of that.

[00:59:09] Resources for Natural Building Techniques

Kenny Coogan: For the listeners who are DIYers, this is the last question. Do you have some good instructional videos or books or, we kind of covered the websites, but do you have some go-to places or even more Google phrases to enter to learn more?

Sigi Koko: If you’re on Facebook or Instagram, I have on Facebook, it’s an album on Instagram. It’s a highlight called Recommended Reads. And I post my favorite books on each topic and I tell you why I like it. For example, on cob construction, the first question I ask somebody is, do you want a book that feels like a textbook that tells you everything you would ever need to know or are you the kind of person who wants to read it like it’s a book and someone’s talking to you? And [01:00:00] depending on their answer, I will recommend a different book. Yeah, so I have those two resources.

Kenny Coogan: Well, we’ll put those links that you mentioned in our show notes, so then listeners can click on your links, which further branch out into more resources.

We wanna thank, uh, Sigi Koko so much for speaking with us today. Our conversation on natural buildings has been very insightful. And we thank you, the listener, for joining our podcast and encourage you to share it with your friends, colleagues, and family. To listen to more podcasts and to learn more, visit our website, www.MotherEarthNews.com. You can also follow our social media platforms from that link.

And remember, no matter how brown your thumb is, you can always cultivate kindness.

[01:00:51] Podcast Credits:

John Moore: You’ve just listened to our episode with Sigi Koko. You can reach us at [01:01:00] Letters@MotherEarthNews.com with any comments or suggestions. Our podcast production team includes Jessica Mitchell, John Moore, and Kenny Coogan.

Music for this episode is “Travel Light” by Jason Shaw. This Mother Earth News and Friends podcast is a production of Ogden Publications. Learn more about us at www.MotherEarthNewscom.

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Meet Sigi Koko

Sigi Koko founded Down to Earth Design in 1998 to help people achieve their dreams of living in natural, healthy homes. Sigi’s uniquely collaborative design process provides a high level of information and support, encouraging her clients to engage fully throughout design and construction. She also teaches natural building workshops.

Additional Resources

• Down to Earth Design
• Follow Down to Earth Design on Instagram and Facebook
• View Sigi Koko’s reading suggestions
• View Sigi’s Recommended Reads list
• NaturalHomes.org
• CASBA (California Straw Building Association)

Our Podcast Team:

Jessica Mitchell, John Moore, and Kenny Coogan
Music: “Travel Light” by Jason Shaw

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The Mother Earth News and Friends Podcasts are a production of Ogden Publications.

Ogden Publications strives to inspire “can-do communities,” which may have different locations, backgrounds, beliefs, and ideals. The viewpoints and lifestyles expressed within Ogden Publications articles are not necessarily shared by the editorial staff or policies but represent the authors’ unique experiences.