Well in looking back at the wall, it ended up taking about as long as I originally estimated on my first guess. I talked myself in to thinking we could do it faster, but it became obvious early on that 2 of us couldn’t lay up the foot a day I had hoped for, we need to add at least one more person to make this efficient. The day we had 3 of us out there, with a big pile of sifted materials, we got the foot lift done in one day.
We ended up putting about:
300 man hours into this project or about 10 man hours per linear foot for a cob pile 6 feet tall, and 2 feet wide, 14 cubic yards in total area, approximately 1/3 to one half straw by volume,
with 2 pressed finish coats and a linseed oil smear.
The materials ended up being a little lower than I expected. Next time I’ll have all the adobe mix delivered, or have all the earth works done and materials sifted, prior to starting the wall. The total materials ended up costing about $500.00 or $6.00 per linear foot.
What I would do different:
I would have at least 3 people on this size of a job. It would make the whole flow smoother.
I’d have all of the materials sifted and ready whether dug on site, prior to the wall starting, or brought in, the cost of labor to harvest on site is much higher than the cost to have it brought in. I found that what Pioneer calls top soil I would call adobe mix that needs a little sand. It was $25.00 a ton with a $60.00 delivery charge.
I would use some kind of flexible form for the footer. Flashing cut in to 6 ” strips and rebar stakes might work.
We will see how this weathers the monsoons. I intend to go out and put one more smear coat on after letting it set up for about a month. I sloped the top a lot and gave it a short drip edge. I expect to see some deterioration during monsoons but nothing that can’t be kept up with.
This job was fun, difficult at times, but fun. We were all happy with the end result.
Start to finish in less than 60 seconds
360 cubic feet over 12 tons of adobe mix type soil some from on site
6 bales of straw
a couple hundred pounds of sand
and a gallon of linseed oil
About 2 months at 3 days a week for 2 people
The next steps will be prepping for the cap getting the final shape, and level, to the top of the core and smoothing out irregularities on the sides. The closer to finish the shape of the core the better. The scratch and finish coats require sifted materials, we want to use as little of these as possible.
Joe came up and helped a day, and learned how to do the mixes, and build up the core.
Having a third person to help with mixes made all the difference. The pace is much smoother and we got to catch breathers. This is the first day we got to the one foot of lift per day pace I wanted to be at from the beginning.