Family Built $40K ADU Greenhouse to Grow Food and Be Self-Sufficient

• Azadeh Weber, 44, lives in rural Washington, about 20 minutes from the closest grocery store.
• She built a greenhouse ADU out of rammed earth and plans to grow fruits and veggies this spring.
• She is excited for her family to be more sustainable and self-sufficient.

This as-told-to essay is based on a conversation with Azadeh Weber, 44, who built an accessory dwelling unit on her rural Spokane, Washington, property. The interview has been edited for length and clarity.

My family and I moved from San Francisco to Spokane, Washington, in 2022.

I’m a clinical psychologist, and both my husband and I have the flexibility to work remotely. We wanted to live somewhere we could buy a larger piece of land.

Our home is in a rural wooded area, with the closest grocery store more than 20 minutes away. We’re also in a location where Uber won’t pick us up.

We live in a large home of about 9,000 square feet, with four bedrooms and five bathrooms. In 2024, we built a 200-square-foot accessory dwelling unit, or ADU, on our 140-acre property.

We didn’t need an ADU for extra space. Instead, my husband and I wanted to make our family more self-sufficient by growing vegetables and fruit on our property.

So we built a passive, solar, rammed-earth ADU that would function as a greenhouse. It will allow us to grow food during the winter when there is less sunlight and warmth in Spokane.

We spent $40,000 on the greenhouse ADU

Rammed earth building is an ancient technique with one of the lowest carbon footprints. It was used to build structures like the Great Wall of China and has been employed in the Middle East.

It’s similar to adobe: you take soil, clay, and gravel and mix them together to form solid walls. Traditionally, the walls are held together with lime. However, our project used about 10% cement.

The rammed earth method is better for growing food than a traditional greenhouse because its walls help maintain a more stable temperature.

It took us about a year to complete, and we finished six months ago. We took a lot of breaks, especially during the winter when it snowed.

The project was self-financed. In total, we spent $40,000. Although it took a lot of work, we are happy with the results. The ADU has a modern feel — I absolutely love how it looks.

Construction was challenging but worth it

My father, an architect specializing in passive solar design, inspired this project. In the 1970s, he received a grant from the US Department of Energy to build five rammed earth structures across Utah. In them, he grew fruits and vegetables.

He and my brother helped my husband and me with our ADU construction. We also hired two contractors who assisted with the labor. We spent about $25,000 on labor and $15,000 on materials.

We purchased our materials from a local store, including polycarbonate sheets, doors, Glauber’s salt, wood, cement, clay, gravel, soil, PVC pipes, and paint. We also used some of the soil from around our home.

The construction process involved a lot of labor.

To build the walls of the ADU, we filled five-gallon buckets with material, mixed it with water in a mixer, poured it into the forms, and used a pneumatic tamper to compact it. After that, we let it set overnight. We repeated this process until we had enough material to form an entire wall.

The rammed earth walls are one foot thick. To optimize passive solar heating and cooling, the building features two north-south walls twice as long as the east and west walls, with a 10-inch gap between them. Beneath the footing, PVC pipes run between the walls and into the structure.

Holes at the top of the walls create a heat pump that circulates air to enhance passive solar heating. The ADU’s roof is also covered with transparent polycarbonate sheets that allow sunlight to enter, while their double panels help retain heat.

In the summer, you can open the vents to release warm air, but in the winter, you close them to keep the air circulating. To further regulate the temperature, we added a Glauber’s-salt bin to the ADU, which will maintain the temperature inside within a range of 40° to 85° Fahrenheit.

We’re still working on the Glauber’s salt system, and its installation is being completed in phases.

We’ll begin growing food this spring

We plan to grow our fruit trees and vegetables in the ADU this spring.

In the meantime, we’re using the space as a yoga studio. I teach yoga online but don’t make much from it. With childcare costs, having a dedicated space at home to teach online is incredibly helpful.

Beyond the practical uses of the ADU, it’s been great for my confidence.

I’m from Iran, where rammed earth is an indigenous building method. This technique connected me to my roots and heritage and brought me closer to my identity.

Having the ADU has also provided an opportunity to teach our kids about growing food and the importance of wellness, which is essential because it will allow us to live fuller lives and better pursue our goals.

I don’t have any major regrets about the project, but I wish I had been more precise rather than figuring things out as we went along. If I were to do it again, I would try to use more building materials sourced directly from the site.

I would also recommend that anyone consider a rammed-earth building experiment with a test wall or even a fire pit before starting the project, as it can be a difficult process.

Overall, my family is enjoying the ADU. We loved watching our vision come to life and anticipating reaping the fruits of our labor.