“Hi Owen. We certainly learned a lot from this building process. The most important lesson was this: someone on site must be familiar with construction techniques and be good at providing quality control and project and crew management. Our experience was that if you are not using volunteers who are independently enthusiastic about earthbag building, the crew will not be able to provide self-checks on making the mix correctly or laying walls that are plumb, level, and square.
Due to budgetary pressures, we were forced to hire manual laborers to build this structure. The salaries we offered (~$10/hr) were not sufficient to get skilled help that could be self-starters. My dad wasn’t able to be outside on the site every step of the way and thus there are a few sections of wall that didn’t receive the exact earth/lime mix required to make solid bags. We’re watching these areas for any movement or shifting, but so far so good nearly 2 years in. I arrived on site after the walls were about 3 feet tall and noticed that nothing was square, level, or plumb. With a lot of measurement and squaring, we got the walls back in shape in enough time to produce a solid house, but it could have been bad if they were any taller by the time we found the problems. We took the unusual step of building this structure with load-bearing earthbag walls. If I did it again, I’d integrate corner posts and some sill beams to ensure structural integrity. Nonetheless, things seem to be ok.
The roof is a traditional vaulted ceiling rafter/beam structure, tied into the top of the walls and the top two courses of bags via 14 inches of top plate and metal strapping. We were lucky to find an out-of-work carpenter to assist with the roof construction, so we’re fairly sure that it was done well.
Also, we should have made the buttresses a bit higher and designed the roof to overhang them more, for water runoff. We’re currently retro-fitting some mini-roofs on the buttresses to keep them from melting!
Furthermore, we found that it was very difficult to find a good exterior adobe mix formula. Folks that have done this kind of thing tend to keep these recipes secret, for some reason. Wanting to avoid using much cement in our adobe, we’ve had to do some experimenting, with mixed results (pun fully intended!). We may end up recoating the exterior with a better mix.
The sole cooling source for the house is a window-mounted AC unit. It keeps the house well below 80 degrees even when it is 100+ outside. The heating system was designed as a glycol-baseboard heating system, but we haven’t fully plumbed it in yet. Again, this is due to the lack of skilled help. My father has been reluctant to hire a standard plumbing contractor for this work, and the ex-plumbers that he did find did a terrible job. We have corrected many mistakes thus far and are sure to find more. Consequently, the house has been heated thus far with electric space heaters, which seem to work very well. Even though the walls do not have much insulative value, the thermal mass does keep things very moderate inside throughout the year. We are also fitting a wood-fired furnace in the common area to heat both homes in the event of a power outage.
We have found that visitors are skeptical that such a lovely little house was actually built with the earth from the site. We’ve kept a piece of interior paneling loose in order to show them the bags from the inside.
We would certainly do this again, but with more professional help and a stronger QA/QC process. All in all, this house has cost around $50k, roughly 1/3 or less of the cost of a similarly sized stick home.”