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In article <625oj0$105m$1@news.ccit.arizona.edu>, cary@afone.as.arizona.edu (Cary Kittrell) wrote:

In article <34463A0B.91914A1E@lucent.com> Rich Pierson <fist@lucent.com> writes:
<I have been giving some thought to building another
<house and have started doing some research on earth
<homes.

I had an interest in earth sheltered housing since the 70's. I still have my copies of the defunct magazine "Earth Sheltered Living" somewhere in a box. The main problem with this construction methods where zoning and cost of construction.
    A lot of zoning laws were written agains GI's after WW2 who would build a basement and cover it with the first floor flooring and tar paper, then live in it until they could afford to build the house.The best zoning laws were in Indiana. In Indiana an earth sheltered house qualified as a "bomb shelter" and was tax exempt. Indiana updated their housing codes real fast.
    The cost of building was the major factor. First you excavated for the footers and piled the dirt. Then put up forms and pour the floor. More forms for the walls strong enough to resist the side loads. Then more forms and pour the roof. Waterproof the structure then bury it. Do not bury it in the winter or it took massive amounts of heat to warm the soil around the house.
   One guy saved a bunch of money by building the walls then filling the house with sand. The sand was rounded on top and became the forms for pouring the roof. Then he removed the sand.
   One guy came up with an alternative construction method. He used a trencher to make a  square slot in the ground. where he wanted doors he did not go as deep. He built a reinforcing rod armature and placed it in the hole. He extended the roof past the walls several feet to act as footers and poured his house. There were no forms and the dirt only had to be moved once. As the dirt was dug out it could be placed immediately on the already poured roof.
  I came up with an even simpler method. On top of a hill dig two parallel footers 30 to 50 feet apart and as long as you want. Place drainage tile in the bottom of the footers. Using a trenching machine between the footers dig trencehs 3 or 4 feet apart 6 or more feet deep. Place plywood or firewood over the trenches and pile the dirt on top. The dirt piled between the footers becomes the forms for pouring the roof. Add your rebar and pour the roof and footers. The roof is an arch which adds to the strength. You will need to run steel rod supports from footer to footer. An engineering concrete CAD program can calulate the loads and rebar positioning. Once the calculations are known for a given width you can make the structure as long as necessary.
   Earth is stable at about 60 degree angle. Look at the embankments along the interstate and you can see examples. Excavate the dirt until you have 7-8 foot of head room and pour the floor. You now have a tunnel as long as you want open at both ends. There are no massive side walls because there are no side loads. Since the roof is built first you are working indoors. The dirt only needs to be moved once and can be put on the roof as soon as it is removed. The inside walls are simple partitions and can be changed later, they are not load bearing. The plumbing can be run in the open space between the walls and the side embankments and remain accessable for repairs. A few vents along the side and you will not have a moisture problem. A front and back wall finish the main structure. Most fire codes are met if you can exit a room in two possible directions so excavate bothe ends..
   A few other advantages to my method. To a casual observer it looks about like pouring a slab foundation for a house that was never built if it needs to be left for a while. A big piece of concrete laying there is not subject to theft or vandalism until needed. The cost should be significantly less than a standard house. Since you start on top of the current ground and then build it higher you are aiding water run off and helping to prevent leaks.
    It you can find a hill that allows both ends to be exposed would be best. Otherwise you have an open end, preferably south and a "courtyard" on the other end. Be sure to provide drainage from the courtyard under the floor before you pour the floor. In a TEOTWAWKI situation you do not add an obvious buiding front but create an unexposed artificial cave.
    The excavation could be done with done with smaller equipment. It is not one massive excavation but a number of sections 3 or 4 foot thick between the original trenches. Dig out one then knock the next one over and shovel it into a wheel barrow or trailer on a garden tractor.
  Hope this helps at least a little.