Building the Hogan

I took a brief hiatus from posting to focus on some other projects, but hopefully I can now get back to regular posting.  I see from the lack of responses that my property tax idea didn’t go over so well.  I was hoping to stimulate some dialog on the issue but perhaps everyone gets enough debate on issues like the economy and the government spending elsewhere.  With that behind us, today I want to talk about something more pertinent to the subject matter - choosing a construction technique.

As you know from previous posts and the title of this journal we’ve already determined the style of house we want to build, that of a traditional Navajo Hogan.  But the style of the house doesn’t by necessity dictate the materials from which it’s built.  Several possibilities for how the house could be constructed were open to us - from traditional timber frame to adobe, strawbale and cob.

Once again we consulted our neighborhood covenants to determine what sort of restrictions might be placed on our construction.  Other than the square footage requirements we discovered that houses could be one of three types: adobe/southwestern, territorial or Earthship.  Since we already had in mind that our house would fall into the first category of adobe/southwestern, this didn’t present much of a problem.  The covenants do not specify how the building should be constructed, only how it should look on the outside.

One of our neighbors is in the construction business in Santa Fe.  He recently finished a very large home on the east side of town (where the money lives).  While he was giving us a tour of another project last winter,  he started to talk about the work he was doing with something called Cob - a mixture of clay, sand and straw.  I had done quite a bit of my own construction and remodeling in my life but I had to admit that I’d never heard of cob until that moment.  He went on to describe the process and he even showed us some of the beautiful results that could be achieved using cob as a solid-surface floor.

Cecilia and I were immediately hooked on the idea of using cob for our own house.  I read up on everything I could find, including the cob Bible, so to speak, The Hand-Sculpted House.  If you haven’t seen what you can do with cob, I suggest you check it out.  We were both excited by the possibility of sculpting all sorts of nooks and niches, benches, reliefs and other creative additions to the house and garden walls.   We even went so far as to book a reservation for a Cob Workshop in Oregon.

Around the same time I began to look at other construction techniques, mainly to understand the pros and cons of building with cob.  I relied heavily on the information from Kelly Hart’s site called Green Home Building.  I compared and contrasted Cob with Strawbale, Rammed Earth, Papercrete, Cordwood and Earthbag.  I quickly discovered that for our region there were a few distinct disadvantages in building with cob.

First of all, building with cob relies on the weather.  You can’t build with cob in the winter, because of the effect of freezing on the soil.  That wipes out quite a few months of building in Taos.  Secondly, you don’t want to build with cob when it’s raining.  The summers here can be wonderful, but they can also bring monsoon-like rain.  This year is a prime example.  We’ve had more days with rain than without so far this spring and summer.  Thirdly, working with cob is S-L-O-W.  You can only build up a wall so fast, even with a team of people helping you.  Cob must set in courses before you begin with the next course.  At the most, you can build one to one and a half foot per day.  Combined with our weather restrictions, slow doesn’t work.

Finally, while it works great as a thermal mass (and therefore as a solar house), another important concern about using cob is that it’s not a great insulator.  Taos is known for its icy cold north wind, even in the spring, and it wouldn’t be wise to have a cob wall facing north.  Of course this can be offset by berming the north side, as you would with an earthship, but that wasn’t something we wanted to do.  We’re keen on preserving the view in all directions.  Another solution would be to use a different material, like strawbale, on the north wall, but if we’re going to go hybrid with our construction we might as well fix the other issues while we’re at it.

Having said all that, I still think cob is an excellent building technique and for the right person in the right location it will be an excellent choice.  We still plan to use cob for our flooring, garden wall and benches.  This are things that can either be made out of the weather, or on our own schedule.

After comparing, contrasting and getting as much information about the various building techniques as I could I came to the conclusion that Earthbag construction best suited our needs.  Needless to say I called to cancel our cob workshop.

I’ll tell you why we chose Earthbag in the next post.