Rammed Earth Homes by Aerecura

By Janet Davies

Graham Cavalier makes houses from dirt. That’s the least romantic way of saying it, but it’s true. Rammed earth building is an ancient technique that produces stylish, sustainable and strong structures, like the Great Wall of China – and Graham’s mother’s house.

“My mom and I started the business in 2009. We named it Aerecura after a Celtic earth goddess, because we actually build walls out of dirt,” says Graham. “Our first project was intended to be my parent’s retirement home, but instead it kicked off a second career for her.”

Sylvia Cook’s first career was high school physics teacher, and when she researched the best way to build a truly sustainable home she chose rammed earth. But there were no rammed earth builders in the province, so she and Graham built Ontario’s first rammed earth home themselves. The ground-breaking home is in Castleton, close to the Big Apple turnoff on Highway 401, and after 10 years it remains Aerecura’s show home. “People really have to experience rammed earth building to understand it and to see how beautiful it is,” says Graham. They host regular Open Houses there and the first 2019 date is in April, check their website for details.

They have built another rammed earth home in Castleton, several buildings up north and homes in Ottawa and Kingston. “We just finished one in Rice Lake, between Peterborough and Coburgh,” says Graham. “Eastern Ontario is becoming our region, which is just one reason I moved here. Prince Edward County is very central and it’s getting a lot of attention which is good news for a business like mine. People are literally building new lives here and I want to be part of that.”

People are calling The County’s stylistic “brand” rustic contemporary.

Graham laughs when we tell him that. “If I had to choose two words to describe my style of home those are the two! I think our buildings fit the feel of The County and places like Kingston. Limestone buildings have such a great connection with the earth, and ours do, too. It feels like we fit here.”


Graham and his wife Lindsey moved to The County in 2016 from Toronto, although it’s fair to say Graham lived wherever he was building and was on the road from May to December. Expecting a baby was the impetus to move.

“We always said we would move to the country to raise a family. I grew up in Alliston when it was a small town and we had the kind of freedom you can’t always give kids in a big city,” he says. “I wanted some land to build our own place, and we wanted to slow down our city pace of life,”

then he laughs. “When we got here we found there’s a lot going on, so it’s not that slow.” Their farmhouse on County Rd. 5 is very close to Spark Box Studio, and Chrissy and Kyle are old friends. “I’ve known them since university, so The County was already like a second home for us. We love the small town comfort and coziness but also this really interesting, beautiful culture where you can eat amazing food! Blumen Garden is just down the road, so is Parsons Brewery, and there’s all these interesting people in the different communities. I love making music so I get out to open mic nights, there’s a lot going on, but it feels relaxed, too.


What’s the major feature of rammed earth homes? Graham says the first thing people generally say when they see one is how beautiful they are, and he agrees. “But more than that, they don’t need a furnace or air conditioner, no matter where they are in Ontario. During that polar vortex we had, I was working near my parents’ place and stayed with them and felt it full force again. No furnace at all, minus 40 outside and indoors it felt the same as it does all year round. The heat of the sun warms up the walls and it stays beautifully temperate, because it’s heavily insulated with no drafts. You make sure leakage points are sealed up and put in enough insulation and the outside air stays outside. In the big ice storm a few years ago, when power was out everywhere around Ontario, they were able to host everybody for Christmas. In fact all the extra people made it even cozier!”

A rammed earth wall acts as a big heat sink. Each wall has a heat sink and, because they are all connected, they share that heat. One big wall is oriented to the sun to soak it up, but anywhere the sun touches will soak it up, too, then release that heat throughout the house. Ontario’s building code still requires a primary heat source. Graham explains that could be in-floor heating. “The standard is one-foot intervals beneath a floor but my parents have 18-inches. In winter that’s your primary heat source, like a furnace you can turn it on. My parents will turn it on once every four days if it hasn’t been sunny, keep it on for a day, then turn it off and it keeps that heat. Of course you can also use a small heater, preferably radiant because the walls will absorb it, but any small heater works and you would rarely have to turn it on.”

Aerecura was the first rammed earth building company in Ontario, but the technology has been used for centuries, particularly in China and the middle east. Britain still has rammed earth structures that are thousands of years old. Rammed earth walls actually gets stronger with age. “We do in a matter of hours what Nature does over thousands of years,” says Graham. “We take a whole bunch of dirt and compress it down into stone, gravity over the years just makes your house stronger.”

They compress the earth in wooden forms which Graham emphasizes are a crucial part of the art. “We build very robust forms to put the material in, they have to be very strong to take that sort of compression. My job as project manager is 50% building those forms, and 50% compressing the earth,” he laughs, “and 50% other stuff, too!” The building material is mostly A gravel, similar to any dirt road you drive on. In fact the Millennium Trail is now A gravel. It compacts very well. They mix it with sand and just a little cement. So it’s just like a concrete wall? “No,”

says Graham. “We use about 5% cement compared to 25% to 30% in a concrete wall. It’s possible to use other things as binders but they are much more difficult to source, not readily available in the building scene.” They add a waterproofing agent and, if requested, can add colour, but not surprisingly most Aerecura clients want their incredible earth walls to be natural, neutral earth coloured! The pictures here show the subtle, sinuous patterns that develop with the layers.

“Using less cement actually adds to the longevity,” he says. “Cement is not naturally waterproof and can suffer seepage and water penetration. Our heavily insulated footings are the only straight cement we use, and even they contain much less cement than conventional stem wall footings. They are mostly insulation.” The walls have six inches of insulation sandwiched between rammed earth which makes for a beautiful aesthetic both inside and out. Should any cold air find its way in, it gets as far as the insulation and stops, ditto the warm indoor air. The homes are equipped with powerful heat exchangers.


Graham laughs at the question. “They’re not totally familiar with it yet, and right now the inspection process for rammed earth is as rigorous as it will ever be. Ottawa and Toronto are the two most difficult places in Ontario to do a build, so generally if you get a building up in either of the big two, the other will say “Oh they let you build there? Okay we’ll consider it.” Their successful Ottawa build means they are on their way.

Tim Krahn literally wrote the book on rammed earth building, and he is their major engineer. He stamps what they do, and that’s what inspectors look for, that engineer’s stamp.

“We do two styles of homes, custom homes where an architect designs it, although we like to be very involved in the process. We do a lot of passive solar heating and there are special qualities of rammed earth we can share with the architect. The other is our own design, the Freya home, named after another Celtic earth goddess, and that is four bedrooms, two bathrooms and can be expanded. That design comes with an engineer stamp.

If inspectors want to talk to our engineer, that’s part of the package, too,” he says.


Aerecura is flexible with finishing. With the Freya home they do the entire shell, the footings, walls, roof right down to the windows. “We use Vetta Windows, and they often call to see if we are free to do installs for other people,” says Graham. “They trust us. We use Havelock metal for the roofs, and we are a preferred contractor with them, too.” Graham’s team will do the whole shell and make sure it’s airtight and all the insulation has been dealt with. Then if you’re handy you can do your own finishing, lay the floors etc. “If you prefer to hire a favourite tradesperson we will always be there to answer questions about a high performance, airtight house and how it affects their work,” he says.

“Having said that, we have a lot of skilled people who do that work, too.

Generally, we like to do the entire shell as the minimum, but we can do just walls, we go case by case,” then he laughs. “We play well with others! We make good working relationships with everyone on the project.”


Graham has a two-tier approach to working in The County. If someone is planning a new build, he really wants to be part of the vernacular, to have people say “Hey you should talk to Aerecura!” Because he firmly believes rammed earth is the best way to build a house today.

“We are a custom, high performance operation. We can’t claim to be anything other than a high end building company,” he says. “But over time we are a less expensive option, with no furnace or air conditioner you save energy and money. Rammed earth building is environmentally sustainable and in the long term financially sustainable. But it is very labour intensive and high skill and we don’t recommend people do it themselves.”

So new builds are one part of his plan. The other is deep energy retrofits that can be done year round. “If someone wants to renovate, we want to encourage them to incorporate the qualities of rammed earth, the same principles of sustainability to bring down heating and cooling bills. Get rid of the drafts, whether it’s an old or new house. It’s a good time to investigate how well your house is running, and if you’re building new or renovating, chances are you’re in for the long haul.”


As well as having friends here, Graham and Lindsey found the baby group run by Peggy Neil helped them to meet people “Having a young family is not conducive to getting out at night and seeing all the activity,” he says with a grin. “It’s been nice becoming part of a community here, and we’ve got to know other young entrepreneurs creating their own way of life in Prince Edward County. We’re meeting people in the same position as us.

We’ve got what we think is an excellent, creative, useful idea that can make us a living, and can also help push The County into being known as a leading edge, sustainably-minded community.”

Graham finds PELA CFDC to be a great resource. “They have been so very helpful, Dominique has been awesome, helping us make business relationships in The County that lead to referrals and connections.” PELA CFDC is currently setting up a meeting with anyone interested in rammed earth technology. “It speaks volumes that something like the Build a New Life campaign is drawing attention to the fact you really can come here to start a new business and get a lot of support from the community and organizations. It’s a tremendous strength in a place when everyone tries their best to support new local businesses.”

Graham plans to get to know the Prince Edward County Homebuilders Association. “With the baby and my existing work I haven’t had the chance!

I’d like to meet the architects in The County, there’s a lot of developing the business to do. I really want to make local relationships. We have a lot to offer The County and obviously The County has so much to offer us.

Not just in business but in our lives.”

On a side note, Graham and Lindsey were crestfallen to have missed getting in on the The Escape Room event at Macaulay House in February. However, since the installation is permanent, there’s the possibility for a different kind of date night any time. “I’m really into long, intense strategy games. And I love that mix of old and new, that there’s this fun new concept happening in an historic old County house. That says a lot about this place, the way it’s moving forward in unique, interesting ways, respecting the history but also using it to engage new people and new activities. I’m excited to be a part of it, and I think we’re going to get along really well here.”

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