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Earthship Volumes III introduced the use of trusses for the roof instead of vigas. Both Janis and I really love the viga look. It is so New Mexico, but the cost and lack of dead standing wood to make them
got us thinking about trusses. We decided to use the "Idiot Proof Truss System" designed by M. Reynolds for all but the front piece.
We decided we would get some of the viga look by using one foot diameter vigas as our front facing support piece for the roof, this also provides a timber large enough to attach the greenhouse to.
Our largest span in the Living Room U was 20 ft, well within the span limits of the Idiot System.
I needed a flat level surface at least 21 feet long and sturdy enough to nail them together. It turned out there was a large open space recently vacated in a local airport hanger I could use for a few days. I ordered the plywood and 2 by 4's to be delivered to the airport, bought 3 cases of liquid nails and a couple more hammers and went to work.
I decided that I would cut the wood and my hired helpers would glue and nail.
Once the truss was done we would load it onto my pickup(lumber rack). At the end of the day we would head up to the house and unload the trusses. I needed two work tables(areas), one where I could place the plywood and 2 by 4's as I cut them and the other for the workers to assemble trusses on. Then switching back and forth as work progressed.
I placed three 4 by 8 foot sheets of pressed wood end to end on the cement hanger floor.
Then nailed a 20 foot 2 by 4 to one edge. This provided an almost perfectly level 4 by 24 ft. work table with a stop edge to assemble the trusses on. I made two of these tables with no legs. Below you can see the two work areas. The one on the left has a truss being assembled the area on the right has the plywood and 2 by 4's cut and laid out for the next assembly. Robert is taking a pose.
I started cutting and the the banging shortly followed. Below is an example of expert Liquid Nail application by Zolie. All 2 by 4' are
glued and nailed per the instructions in Vol. III. It was so cold the night before we had to run a space heater on the glue to get them heated up o the glue would flow smoothly. Surprising by
planning out the cuts there was very little scrap lumber left over when we were all done. We found many uses for the scraps we did make later on which you see in later sections.
There were 28 trusses to build at the airport, two small ones that were less than 8 ft. long we built on site. It took 2 and a half days to construct and transport them to the house site. Below is the
repository of trusses waiting to be installed after two days of assembly. Now we get to find out how accurately I placed the feet in the bond beam a few weeks ago. The feet are treated 2 by 6's
one foot long that are pin-coushined with 16D nails on one side and placed in a cement patty during the bond beam pour.
The first row is on and they look great. We are installing the middle U truss first and then following with the two outer U's. The trusses overlap 6 inches where the inner truss meets the outer
trusses. So far the truss feet are right on. I expect some shimming to be necessary but would like to keep it at a minimum.
We then installed the last truss for the middle U. A line from the front middle truss to the back middle truss was our guide for the rest of the house. Install the next middle U truss alligned to the
line, then install the two outer trusses aligned with the middle truss and so on.
We proceed to install them one row at a time starting with the middle truss and then the outer ones as we did the first row. This allows us to carry the trusses down the top of the bond beam We
have to lift the middle truss over the last one in it's row but this is the narrowest U so the trusses are not very heavey. The end U's are the big U's and we don't have to lift them above another truss.
The longer trusses are pretty heavy. We muscle them up onto the bond beam and them step them down the walls one side at a time. Below we have the first four rows set and the 5th row middle U
set. You can see the 'X' bracing being installed, one set installed every six feet. You can also see the last truss installed and temp. braced at the top of the middle U.
One of the down sides to the Idiot System is the nails. The 8D nails used on the top 2 by 4 are about a 1/4 inch too long and the sharp end sticks out. We all have numerous tears in our pants
and shirts from getting snagged while crawling around on and through the trusses.
We get the trusses installed in almost the same time it took to build them. What a major transformation of our Earthship! Five months to get to the point of being ready for the trusses, five days
to construct and install them!
So its now time for the front Vigas!! Here I am below installing the viga for the master bedroom U!
Yeah right!!!! Here's the real picture of installing the viga! We chained the viga to the front bucket of a backhoe/front loader.
Lifted and placed it nearly in place. Then shoved it into place with the backhoe. Each end of each viga is double nailed to a foot with two pieces of 5/8 rebar. Then strapped down to the foot with 1 and
1/2 inch 18 gage strapping. The foot is two, 2 by 12's set into the bond beam. The 2 by 12's are nailed and glued together.
Here's the truss and viga combination. The vigas turned out to be between 13 and 14 inches in diameter. They are beautiful. We will try to keep as much of them exposed to the interior as we can.
Next comes the front tire wall. Back to pounding tires! I never thought I would miss it but its a comforting thought to know tomorrow I'll be pounding away making 400 lb. thermal mass
bricks for my house again. We have also started on the interior of the two 3500 gallon water cisterns on each end of the house.
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