Saturday, September 26, 2009
It's the end of September and we are nearing completion of the structural elements. We have a few small slabs to pour, then it will be time to settle in for a winter of carpentry.
Last week, after we put on the SIPs and bolted down all of the beams, Khyber built a chimney using Integrity Blocks, Abe installed the plumbing waste and supply lines, pressure tested all of the buried copper and radiant tubing, Terra sealed the walls, and we orchestrated a major clean-up of the site. The forming system is disassembled, cleaned, and bundled together to move to the next project. The tools are reorganized in the job trailer, the table saw and chop saw moved into the kitchen/winter cabinet shop, and the miscellaneous screws, nuts, and bolts sorted into empty paint buckets. If this were a paying job, the client would be writing a big check.
In October, Khyber and Taj are going to Maui to start reconnaissance for a project there this winter. Abe and Terra are about to become finish carpenters, and I am going to Mexico to see some of the rammed earth projects underway as a result of our workshop there two years ago.
The posts in Terra's blog will be less frequent, but check in from time to time to see how things shape up. The photos in this post give you a sense of how the house will look finished. The square hole in the wall to the right of the fireplace will be a wood-fired boiler and bread oven, used to heat the water for the radiant floor.
Tuesday, September 15, 2009
Yesterday was the BIG day. We'd finished installing the rammed earth in the master bedroom last Thursday, then spent Friday pulling screws and form ties. But Monday was the day we had been waiting for all summer. We were about to see the house. Gilbeau showed up with his crane truck at 9:30 and we got started right away. Gabe and Edward were rigging and taking down the form panels one at a time and laying them along the east side of the building for disassembly and clean-up. As soon as one panel came off, Taj pulled out the beam pocket forms behind it and set the hangers. Abe and his brother Flynn were cutting and notching beams as fast as they could go, trying to stay ahead of the crane. Khyber and I were fabricating the clerestory frames and Rigo was removing door bucks. That part took about three hours.
After lunch, Gilbeau starting settng the six big beams with his crane and we set the smaller ones off of ladders. Once the timber was in place (about two hours) n we started picking and setting the SIPs. The big panels were 8' x 20', the smaller ones 8' x 10'. It didn't take more than ten minutes per panel. By five o'clock we were done. Take a look at the pictures.
They illustrate Taj working on a beam pocket, one of the form panels being lifted out of the bedroom, setting one of the beams, setting one of the SIPs, and a view of the house taken at 5:00 pm.
Saturday, September 12, 2009
The master bedroom was the final piece of the wall tryptic that anchors the house. The walls for this building were sixteen inches taller than the first two modules, plus the room was eighteen inches longer to accommodate the big closets and the fireplace, both built within the walls. (We''ll discuss the whole process of niches and spaces "carved" out of walls in an upcoming post.)
We allowed three days for the ramming and bond beam and used a crew of seven: Edward on the mix machine, Khyber on the delivery conveyor with Terra helping to check lift depth, and Taj, Gabe, Abe, and Rigo on rammers. It took roughly 120 man-hours for the placement of sixty yards of rammed earth plus six yards of bond beam.
One of the time consuming elements in constructing a system like this is prepping for the changes in wall top elevations and the locators for roof framing. Terra and I calculated that we spent twenty man-hours installing shut-offs, top of wall ledgers, and block-outs for beam pockets. This all took place the morning of the third day, after most of the rammed earth had been installed but before the bond beam was poured.
The living room side of the wall also has the Rumford fireplace plus the pizza oven/wood-fired water heating system for the floor slab. Basically, everything that gets embedded in a rammed earth wall, whether it's an electrical box, closet, beam pocket, or fireplace, takes extra time and extra care to make sure it is square, plumb, and precise.
It was a great three days and we celebrated with a chocolate cake at lunch. All of the equipment, including the rotating delivery conveyor, worked flawlessly. We designed and built a new chute for the outfall end that gave Khyber more accurate control over placement. Edward added 2% more water to the mix which combined with slightly smaller lift depths (seven to eight inches rather than eight to ten) gave us tighter compaction. Smaller lifts did decrease production rates, but not significantly. We'll see whether the decreased lift depth translated to improved quality when we strip the forms on Monday.
The photos in this post illustrate the formwork, delivery, ramming, plus one special shot of the homeowners, looking like they built the walls single handedly.
Saturday, September 5, 2009
We're two-thirds of the way through wall building, getting ready for the final piece of the tryptic this week. Things have been going just about as well as we could have hoped for. One of the especially fun parts of the experiment has been the success of our multiple conveyor delivery system.
In the recently old days, rammed earth was built by mixing on the ground with a tractor bucket and rototiller, then transporting the mixed material to the forms and shoveling out of the bucket. Starting in the late nineties, in an effort to speed up production, we began using mix augers for proportioning and blending. After that we started designing and building articulated conveyor belts for moving material and dropping it directly into the forms. Each project gave us an opportunity for subtle improvements to the system.
At Terra's house we introduced for the first time a rotating delivery conveyor that mounts to a hub in the center of the building. The mixing machine drops onto a first conveyor which then takes material to a second conveyor which reaches over the formwork to the center of the building. The rotating conveyor spins on a "lazy Susan" and rides along the top of the wall form to deliver material right to where it's needed. No shoveling!
The rate of delivery is adjusted to match the speed at which the rammers can compact the material. At Terra's we're using four men on rammers and placing about five cubic yards per hour. If we had more people on rammers, we could double the rate of production.
To be sure, the equipment adds to the capital investment required for wall construction, but it improves the uniformity of the mix, increases the rate of production, and adds credibility to the process for engineers and building inspectors.
The photos in this post illustrate the conveyors, the mixing machine, and the team of rammers laying down the mix behind the rotating delivery conveyor.