- A Montana couple spent over 2 years building their 700-square-foot cob house by hand.
- Daniel Ray, the owner, estimates that they spent less than $20,000 on the entire construction.
- Now, the couple runs a business hosting workshops to teach others how to build their own sustainable houses.
Building an earthen home from scratch might sound daunting to some, but for Daniel and Katherine Ray, it’s their way of life.
The Montana couple, who started dating in high school, first came across cob houses when they were in college. Cob is a natural building material made out of clay, sand, and straw.
“We stumbled across a photo of a cob house in Wales and we got really interested, so we started collecting lots of pictures of other people’s cob houses. It was a pot-shot dream that we really wanted to do,” Ray told Insider.
But it wasn’t until a couple of years later that the couple finally had a chance to turn it into reality.
“After we completed college, we moved to Vancouver, British Columbia, so I could finish my master’s degree in library science,” Ray said. “After we moved back to Montana, I didn’t have a job lined up yet, and we were renting — so we thought it would be the perfect time to build a cob house.”
Ray’s parents owned an empty acre of land that used to be a horse pasture, and they granted the couple permission to build on it.
“And so we did. Our first home was like a 300-square-foot cob house on their property,” Ray said.
After three years, the couple decided they wanted to build a bigger home on land that they owned.
They saw their first cob house as practice for the new space they had in mind.
Ray and his wife purchased a plot of land in the Bitterroot Valley in Victor, Montana, and started building their second cob house in the spring of 2016. They did not share how much they paid for the land.
It was a massive undertaking: The couple spent almost three years trying to complete the project by hand, Ray said.
“We both had full-time jobs and then would also work about 40 hours a week on building the house,” Ray said.
“It was a lot of work for over two years. I mean, if somebody was able to take a couple of years off to build their house, they’d probably be able to do it a lot quicker than us,” he added.
The couple was involved in every part of the construction process.
Not only did they design the blueprints for the house, but they were also responsible for sourcing the natural materials required to build the structure.
The couple used their feet to make cob by mixing dirt, clay, straw, and water.
“To make cob, you basically take dirt that has a solid amount of clay content — which is usually anywhere from 30 to 50% clay — and you mix with water until it’s a good mud-like consistency before you add straw,” Ray said. “You stomp it all together, so you’re just mixing it on tarps with your feet.”
Most of the building materials needed were sourced locally, Ray said.
“All of the straw that we used for the walls is from the area. All of the soil, which is the main component of the walls, is from a quarry that’s about five miles away from the house,” he said.
Unlike bricks, which have to be held together by mortar, the walls of a cob house are built upwards in a single layer, Ray said.
“The walls are just one full solid piece,” he added.
The process of building a cob house is quite similar to building a regular home.
Before the walls could be constructed, the couple had to first excavate the ground to make space for the foundation.
“We rented a small excavator, dug the foundation out, and then we just started building from the ground up,” Ray said. “It’s just like a normal stick-frame house or anything like that.”
Although the couple had experience from building their previous cob home, the two of them aren’t professionally trained in construction.
“We both graduated with anthropology degrees, and I have a master’s in library and information science, so I’m really good at doing research,” Ray said. “We had zero contracting experience. Neither of us had built anything really, other than cabinets and stuff like that.”
Thankfully, family members chipped in to help whenever they could, which meant that they didn’t have to hire any external contractors, he added.
Depending on the location where the cob house is constructed, building permits might be required.
“So where we’re located, there are not very many building codes or permitting required — that’s kind of the reason that we chose the area as well,” Ray said.
But that’s not to say that people can’t build cob houses in areas with stricter rules, he said. They still can — as long as they have an architect to sign off on their plans.
“The big thing is you’d have to get those permits to have a bank give you a loan to build a house. But if you’re building a house for so cheap, you don’t necessarily need a bank to loan you money,” he added.
The couple learned how to build their cob house using books and online resources.
“We really had three books that were our guiding principles for building,” Ray said. “And the main idea is that anybody could build a house — it’s not rocket science. There are a lot of specialized construction industries that make people feel like they can’t when it’s actually something that they can do.”
Even though earthen houses are commonly found in countries like Mexico and India, this building method hasn’t quite taken off in the same way in the US, he added.
Since the couple’s cob house has a large floor area, three wooden posts are used to support a center beam that holds up the roof.
But this is a feature that a smaller house might not need, Ray said: “Our first house didn’t — the distance between the walls was much shorter, and so we just had beams spanning from one side to the other.”
Unlike a normal house, the walls of a cob house do not have any wood framing.
“It’s straw bale and cob hybrid structure where you’re building up layers of bale with four to six inches of cob on the inside,” he added.
The couple created built-in furniture by shaping tabletops and shelves out of earth, including the bathroom counter.
“We adopted a technique that uses lime plaster instead of clay plaster, and that’s finished with an olive oil soap that waterproofs it,” Ray said. “It’s a Moroccan technique called Tadelakt.”
Moreover, almost everything in the house — including the walls — is curved, he said.
“There’s no straight wall, there are no 90-degree corners in the house, really. It makes for a much more aesthetically-pleasing structure,” he added.
That said, Ray still thinks that the most charming parts of the house are the window sills.
“The walls are two and a half feet thick, so all the window sills are that deep,” he said. “It creates a really beautiful space.”
The couple’s completed cob house is about 750 square feet. It comprises a 600-square-foot main floor and a 150-square-foot loft.
The couple moved into their new cob house in the fall of 2019 — shortly after Katherine gave birth to their daughter.
There are two bedrooms and one bathroom in the house. Ray says they draw electricity from the grid and rely on a well on the property for water.
Instead of a flushing toilet, the couple uses a composting toilet in their bathroom.
“It’s a sawdust toilet,” Ray said. “So after you use the toilet, you put sawdust on it, and then it gets emptied into a larger composting area we have on the property.”
One of the benefits of living in a cob house is that the interiors are much cooler than typical houses during summer.
“Our walls are two and a half feet thick — they absorb a lot of heat from the sun and from our wood stove inside. And then it reflects back during the day,” Ray said,
Although temperatures in Montana can go up to between 90 to 100 degrees Fahrenheit during the summer, temperatures in the cob house can stay in the low 70s without air conditioning, he added.
Ray estimates they spent less than $20,000 building their cob house.
“Compared to other homes in our area, most houses are being built for between around $150,000 to $200,000,” Ray said.
Houses nearer the town center in Victor are even more expensive, with a median listing home price of $866,000, per data from real-estate platform Realtor.com.
Since the couple paid for their cob house out of pocket, they don’t have housing debt.
“A house like this could be as inexpensive or expensive as you want it to be,” Ray said. “The first house that we built, we didn’t have any money then, so it cost us about $3,000 to $4,000 to build that 300-square-foot house. But then this house is much bigger and has more amenities, so it was more expensive.”
Now, Ray and his wife are running a business teaching others to build sustainable cob houses too.
Rather than doing commissioned builds for others, the couple’s central focus is spreading knowledge through workshops.
“Especially in the area that we are right now, there’s an influx of people moving in — it’s kind of a housing crisis where we’re at with people losing their rentals and their homes,” Ray said. “It’s really important that people know that they have other housing options.”
The costs of the workshops range between $120 to $500, and they cover specific topics such as how to make earth-based plasters or install earthen floors, per the couple’s website.
They also host four-day and nine-day building immersion camps where participants learn how to build a full structure by working on a guest house.
There’s no age limit on who can join the workshops, although minors will need a parent to sign off on their participation, Ray said.
“We have kids come to our classes to learn how to do stuff too — it’s family-friendly,” he added.
For those who are interested in building cob houses, Ray has one piece of advice: Try to downsize as much as possible.
“If you design a house that’s much more compact, it’s going to reduce the price by a huge amount. It’s also going to reduce the amount of effort that you have to put into building the house,” Ray said.
Anyone interested in building cob houses should also research as much as they can — not just on the building techniques, but also on what types of material options are available to them locally, he said.
“It doesn’t make sense to build a straw bale house in an area where you have to import straw from elsewhere. That’s where you save a lot of money — by using local resources,” he added.