After the hand-thrown walls, earth plasters, and soil-cement floors it was finally time to get going with rammed earth. We thought a few low walls for an outdoor shower would be a good place to start. Six feet high, eight inches thick and no roof load, but exposed to all the Hana rain and to the shower water would be a good introduction to how well rammed earth could work in this climate. The backside of the wall serves as a landscape wall for the front door to the main pavilion.
We poured concrete footings and then set short section wall forms much like we did years ago on the mainland. We only had a small 13 cfm air compressor that would barely power a Jet 2-T rammer, so most of the wall was rammed by hand. Evan and Dan helped with the first corner, then Cindy's brother Alan and his kids came for a week to help on the shower wall and to plant bamboo. Khyber and Taj were here as well, so it was a family wall raising. It only took a few days.
We were trying to arrive at a good mix design for rammed earth that wouldn't require import from the other side of the island. The soil on site has no plasticity, being all volcanic in origin and not old in geologic terms, but it is expansive and will crack if not modified with aggregate. We added about 40% coarse red cinders that are available here in Hana and 7% Hawaiian cement. Getting the correct water content was also tricky. We had a tendency to overwater the mix and then ramming was a little spongy. We only had four wall sections total, but felt pretty good about how things turned out in the end.
The walls have now been exposed to seventy inches of annual rainfall for eight years and the surfaces are as durable as the day we stripped the forms. Mosses and lichens have colonized the face; blue ginger and yellow alamanda grow against them. Ferns grow in the joint between the base of the wall and the shower floor.
The shower walls gave us all the confidence we needed to move into the first of the rammed earth pavilions, which I'll describe in upcoming posts.
Aloha David, thanks for posting here on your experiences with rammed earth in Hawaii. This is very interesting and informative. I was aware that you had done some work on Maui, but it's great to see & read about the details. Hoping to make a few projects happen over here on Kauai someday soon.
ReplyDeleteThanks guys!. Great blog. I am interested in building with rammed earth in a tropical rural area. I have two questions:
ReplyDeletea) did you have any problem with humidity. Most people is sceptic about using rammed earth in tropical rainforest places, because of the potential erosion of the rammed earth walls.
b) Do you have an estimate of the final cost of the house, per square meter or foot?.
Thanks again.
Alvaro (from Ecuador, South America)
I have built 3 rammed earth villa in the tropics Bali Indonesia with no problem at all FB Bali Griya rammedearth solutions
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