Freezing nighttime temperatures have brought our Superadobe/Hyperadobe building to a pause for the winter, but I'd like to provide an update about what we learned and built this year. I want to keep sharing answers to questions I've found about how to build for healthy living without going into debt.
I have to say that building with earth is a lot of work, but it's also a lot of fun shaping a structure from the earth beneath your feet. There's an artistic element to it similar to sculpting.
But one of the coolest things about Superadobe is making roofs and large openings such as windows and doors without post and beam elements (this typically uses wood which is highly prone to condensation and mold in these settings). The way to do this is with arches. A 360° arch is a dome. It's a little intimidating the first time you make one because earth weighs a lot! And what if it collapses? But arches and domes are actually some of the strongest designs to build which is why they've been used throughout the ages.
To make a Superadobe arch you make a form to help support it until the adobe sets up (a form isn't necessary for a dome - gravity's pull makes it stronger). Typically this is done with wood. I had started making an arched door form with wood, but it was near the beginning of monsoon season and the wood started growing mold as a result of all the moisture (we found wood for sale in the big box stores with mold already growing on it). There's no way I was going to use that! What I settled on was using 1/2" PVC conduit for the form with the hopes that it would be strong enough.
Before building a door arch in a dome with my PVC form (there's no undo button for that) I wanted to test the top half of the form where the arch shape is located to see if it could handle the weight of earth. But if we were going to go through the work of building an experimental arch, we wanted to use it for something. We decided on using it for a sign. We used just soil and water - no lime stabilizer. We had a number of neighbors stop to ask what we were building and share what they had guessed it was (eg. dog house, fire house, our house).
Since the PVC arch form handled the weight of the earth alright we went ahead with using it in our first dome. The good news is it worked! And we have the pictures to prove it!
This 8' diameter, 50 square foot dome is super basic, but it cost us less than $1000 to build. Not bad! The possibilities are only limited by your imagination. They say a team of six - with only one of them knowing how to do it - can build a dome this size in a week working 8-hour days. It took us two months but we had the initial learning curve and a lot of interruptions.
In the county we live in, a building permit isn't required for anything under 200 square feet and without utilities so we didn't have that expense or hassle. I've heard that it's similar in many counties.
Superadobe is over-engineered in multiple ways so that even if a mistake or two is made, it is highly unlikely to cause failure. This whole dome build was pretty experimental for us. We really wanted to build one and go through the learning curve before we invited others to join the experience. Now that we've done it we'd be happy to have folks come out to learn and help with additional dome builds when it warms up in the spring.
“For every house is built by someone, but the builder of all things is God.” (Heb 3:4)
Dedicated Christian, patriot, family man, founder of Sabbatical Ranch