The Adanado Rammed Earth Home

When most people walk onto a piece of property, what possibilities do they imagine for their future dream home? They might reflect on the views, the proximity to the nearest town, the quality of the school district, and other common considerations. For Johnna Barrett of the architectural and real estate development firm Barrett Design, however, looking at the soil underneath her feet was one of the most essential criteria for designing her future home.

Over the past several years, Barrett and her husband Sid have designed and built a beautiful rammed earth home in the San Luis Valley of southern Colorado. Located at an altitude of 7,600 feet in one of the highest alpine valleys in the world, Barrett's rammed earth home is entirely off-grid. It's 100 percent powered by solar panels. And, even though winter temperatures can plunge to 50 degrees below zero, an evacuated tube solar hot water collector system heats their hot water.

The thick thermal mass of the walls of the home, created entirely from the soil that they excavated on-site, protects the couple from the cold winter winds and the hot summer. In a recent interview with Rise, Barrett shared essential insights and advice related to how she and her husband designed and built a home constructed from locally-sourced materials.

Tell us about the design of your Adanado rammed earth home. 

Our Adanado home's interior is 1,160 square feet. It is a simple layout—living room on one side, master bedroom on the other, and the kitchen bridges the two primary spaces. Between the bedroom and living room, there is a large covered terrace. It has a spectacular view of Mt. Blanca, the Great Sand Dunes National Monument, and several other 14ers (14,000-foot-high peaks). There is also a small study adjacent to the living room that can be used as a second bedroom.

What are some of the primary sustainability features? 

The house was built literally from the earth on site. That means very few materials were trucked into the site, and for those, we used as many locally sourced materials as we could find. The forms for the walls were plywood that, when removed from the walls, we used as our roof sheathing. We are completely off-grid. A well was dug before the beginning of construction, and a solar panel was installed to operate it. All of our power is solar energy; we are not grid-tied. We have a battery bank for electricity storage, and our heating comes from the sun. We installed an evacuated tube system for both domestic hot water and floor heating. The sun heats the liquid, which then flows into our storage tank and circulates through the home. We made our own clay wall finishes for the interior surfaces.

Why did you decide on rammed earth construction? 

I wanted to build something that genuinely appears to have grown up from the land organically. To be able to use the soil on-site and sculpt it into inhabitable forms; that was truly special. And the finished wall surface is beautiful! Added bonus.

What proportion of cement was used to stabilize the walls? 

Approximately nine percent. We started at seven percent. But we found that due to the high sand content and lower clay content of our native soil, we needed to increase the amount of Portland to ensure stabilization slightly.

I saw that you excavated all of the soil for the walls on-site. Does this contribute to reducing the embodied energy of the home? Can most house sites do this? 

It significantly reduces the carbon footprint. Before using site soils, get them tested. Salt content is a significant factor, as too much can cause the walls to deteriorate. You need the right blend of sand and clay, and the topsoil needs to be removed past the root zone of any plant material. The testing process is simple. You can send samples to companies for sodium analysis; a clay/sand analysis is as simple as putting your soil in a jar with water and seeing how it settles out. Many times soil can be supplemented if what you have on-site isn't ideal. Road base is a material that is frequently used for rammed earth walls and is relatively inexpensive and sourced locally.

What can you tell us about how rammed earth homes help with temperature control and indoor air quality? 

The walls moderate temperature due to their thermal mass. Once heated, they remain warm and radiate heat back into the space. This minimizes the heating load during the winter. In the summer, we open the windows in the evening to let in the cool desert air. Once the walls are cool, they stay cool all day, which means we don't need air conditioning. Earthen walls and clay finished walls have no off-gassing. As natural substances, they breathe and help regulate indoor humidity.

Has the home received LEED certification or some other type of green building certification? 

It has not, but only because I never followed through with the final rating! We were living in Atlanta, GA, when the house was completed and the only green raters available were in Denver. I flew them down to our site during construction, so all of the preliminary rating information is in their system. The only thing left to do once construction was complete was landscaping.

Funny story: I planted xeric plants, installed a drip irrigation system, the works. Did it all myself. Left for a month, came back to the house and it was a disaster! The jackrabbits had eaten everything literally except for the Russian sage. We had wild llamas show up who ate all of the xeric grasses. And the little desert mice had eaten into all of the drip lines, making them unusable. At that point, I realized that living in an environment as harsh as the one we had selected was going to take a tremendous amount of ongoing work. And that little piece of paper from a certifying agency saying I had done a great job didn't seem as important. The house should qualify for LEED Platinum if I ever take the time to fly the raters down again. We will see.

What advice or suggestions would you offer to somebody interested in building or living in a rammed earth home? 

Just know that it may turn out to be one of the most difficult two-week endeavors that you ever attempt, especially if you are in a somewhat harsh environment. We could only work when the sun was out to power our well. We worked in the brutal sun. One day, 50-mph winds spun people holding sheets of plywood around in the sand.

If you plan to keep the exterior wall surface exposed, make sure to add a sealant into the mix, as water over time can cause some deterioration, even in a desert environment. This is especially true if you live in an area with high winds and sand. Once you start the building process, there's no stopping. But the moment you pull those forms off the walls, it becomes 100 percent worth it. Living in the home is a dream. The walls are so strong, and the interiors are comfortable and quiet. We don't worry about heating and cooling, and we are very tuned in to nature—a side benefit of living off-grid. 

Article by:

Tobias Roberts

Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.