We were just talking about strawbale roundhouses the other day. (See: Straw Bale Roundhouses Built in One Day.) This one is in New Mexico. I highly encourage people to try gravel bag foundations. (Polypropylene bags or tubes filled with gravel.) They could have saved a great deal of time, money and effort. A small, simple foundation like this one can be built in one day with two workers. Our free websites and articles explain the details.
Tips:
– Double bag gravel bag foundations (one bag inside the other) for added strength.
– Fill bags with scoria/lava rock if you want insulated foundations.
– Use baling twine or poly or nylon strapping to stabilize bags of lightweight fill material (prevent shifting) and to secure the first course of bales to the bags.
– Use 18”x30” poly bags. They will align perfectly with most straw bales.
Hello Owen,
I’m a teacher at Taos High School and I wanted to get involved in building straw bale structures in the Taos area this summer. I’ve been in contact with some passive solar builders and solar designers out in Mora and Two Peaks. I had spent the summer of 2014 interning with Earthship Biotecture. I wanted to research models of building that are simple, thrifty, low-skill, and durable so I can get this technology out to the Navajo Reservation (where I’m from).
I was wondering if I could get out to see the beautiful roundhouse some time and perhaps interview you for a book I’m working on. I’ve published two books through UNM Press and I’ve also written for High Country News. I’d be happy to learn as much from you as I can!
All the best,
Jim Kristofic
Hi Jim. Thanks for writing. The Navajo library (can’t remember the name) has a copy of my dissertation about sustainable building for the Navajos. It exams in detail the best options and the obstacles/barriers of working in the region. Check it out and let me know what you think. While I leave it open for readers to decide what’s best for them, I lean heavily toward strawbale building for the Navajos. Adobe is another obvious favorite. Email me any time if you have questions. My address is at the top of the page under About Us.
Hi Owen, for some reason I was under the impression that traditional concrete foundations are a requirement in NM even for earthbag buildings. But I would love to be wrong about that. Does it depend on the specific county? My husband and I are dreaming about building an earthbag home in Bernalillo county…
My point was to encourage people who live in no or low building code areas to use earthbag foundations. NM has statewide codes and so it’s more difficult to build earthbag foundations. It’s possible to get an engineer to approve the idea like has been done with rammed tire foundations, but this is an uphill battle that requires patience and lots of money. It’s much more difficult to do things like this in or near big cities. In your case you’ll probably have to use a concrete foundation. See if you can find an engineer to minimize the use of concrete:
– grade beam on rubble trench
– frost protected insulated foundation
– fly ash or other pozzolonics in the concrete mix
Owen, what is the method for securing the bale walls to the gravel bag foundation?
Baling twine is probably the easiest. Place the twine between the earthbags as they’re stacked. Put the twine two courses below the bales. Baling twine is available at all farm and ranch supply stores and sometimes feed stores.
Some use poly or nylon strapping. But that requires a special tightening tool and it’s more expensive.
I can dig it :)