Build an earth-sheltered log cabin...By Tok Thompson by SUSB

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									BUILDING                                                                            May/June 1994 Backwoods Home Magazine




Build an earth-sheltered log cabin
           By Tok Thompson                   nowhere in all the literature on            amazed at how easy it was to debark
                                             earth-sheltered construction did I find     them.
         ver a period of three summers,

O        for a total of five months, I
         designed and built an
earth -sheltered, passive-solar cabin.
                                             any log-based plans, which is due, I’m
                                             sure, to these very considerations. To
                                             counter the problems, I relied on mod-
                                             ern technology, including surrounding
                                                                                            If you decide to cut fresh trees and
                                                                                         debark them as I originally did, how
                                                                                         ever, be prepared for some work.
                                                                                         Most log builders recommend using a
                                                                                                                                -


The structure is 12x30 feet, with the        the house in metal siding, and coating      drawknife, which has two handles, for
main room being 12x20 feet. Besides          the outside of the logs in copper           stripping off the bark. For me, it
the main room, I have an ample-sized         napthalmate. It is a noxious substance,     proved easier to use my machete,
bathroom and a “mud room” entry-             but good at stopping rot. A more            which I could grip on both sides while
way. The cabin is sunny, comfy, and          eco-friendly way would be the old           wearing a glove, and which had the
easy to heat. The total cost? Under          Norwegian method of curing the logs         added benefit of a point for use in
$1,500.                                      in salt water, or just using driftwood.     working on tough spots. The machete
  In essence, the design is a sod igloo,     For additional insurance, I installed       also made hacking off branches or
perfected over thousands of years by         PVC pipe both inside and outside the        other obstructions mercifully easier
northern-dwelling indigenous peoples.        house to drain any water down and out       for me. The only other tools I used in
The main function of the earth-shel-         beneath the floor. I may have done          this process were a chain saw and a
tered design for them was the heat           more than minimally necessary to            log-turner.
efficiency. Whatever heat seeps out of       keep our house nice and dry, but I did-        Assuming you have the site and the
an above-ground house is whisked             n’t want to take the chance that I          trees, the first job in construction is
away by the wind, but in an                  might have to dig out the walls later       digging the hole. Although a backhoe
earth-sheltered dwelling it is kept next     for repairs!                                would be ideal, you can make do with
to the house, dramatically slowing the         I had cut and stripped all the logs the   a bulldozer, as I did. Digging the pit
heat loss process.                           fall before, to give them a year to cure    by hand, although possible, would be
  For someone to build a similar             and dry. Preparing the logs was actu-       a monumental task. Before you dig,
house for a similar price would not be       ally the most strenuous part of the         however, be certain the proposed pit is
that difficult. Of course, I scrounged       process. It took me a month and a           situated on the site exactly as you like
for building materials as much as pos-       half of constant work, and along the        it. For maximum sun, the front should
sible. I purchased, for a mere $80 at a      way I learned a few things.                 be pointed south, although I chose to
moving sale, enough metal roofing to           First of all, there are several ways to   compromise between sunshine and the
entirely surround the cabin, along with      make sure the logs are cured. One way       best view of the lake. A slight rise to
a large front window set for $20. The        is to kill them while still standing by     the north is ideal, and be sure to have
window was initially too big for the         peeling off the bark all the way around     a good sand or gravel base.
hole, so I widened the space with a          the tree and waiting until they dry out
chain saw to make it fit. Lumber for
the foundation, floor, and roof totaled
                                             before cutting them down. Another           Laying a foundation
                                             way, which is the one I used, is to cut
$1100. I was able to barter for the use      them down, take off all the bark and          There are several ways you could
of a bulldozer, which otherwise would        branches, and prop them up off the          build a foundation for your cabin.
have been very expensive. Someone            ground to dry. Still easier, however, is    Poured concrete or chemically treated
was throwing the front door away at a        to use trees which are already dead,        beams seem to make the most sense
local dump, and they were only too           especially those that are still standing.   for this project. The adventurous
happy to have it put to good use.            Around the area where I live there is a     could forego this step and rely on
Where I live, trees are free or freely       kind of tree beetle that will kill spruce   treated logs. I chose treated 2x12 lum-
given by neighbors, which is what            trees without harming much of the           ber, two thick, creating the net effect
prompted my use of them as my main           wood. Since things rot so slowly in         of 4x12 wood beams. After carefully
building material.                           Alaska, these trees often stand for         leveling these, I lay thick Visquene
  The biggest problem with sod igloos        years, drying and curing naturally.         (polyethylene) over them, to act as
is their tendency to leak water and,         Towards the end of my building pro-         another moisture barrier between the
after leaking, to eventually rot. In fact,   ject, I used some of these and was          house and the ground below, and then



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May/June 1994 Backwoods Home Magazine


built a subfloor of 2x6 lumber and           ered and buried, but by the time you       floor, using two-foot spacing boards
CDX plywood.                                 get to those you should be getting the     along two walls, and plywood was
  I ran a 2x6 header board lengthwise        hang of log work. I recommend laying       nailed over the top of them.
along the house and nailed the 2x6           insulation between the logs, especially       I laid aluminum roofing on top of
support joists into it. If I had been        if you are not doing any elaborate fit-    that, as well as over the portion of the
building the cabin any wider, 2x6            ting techniques.                           log walls that would be buried. I put
lumber would not have sufficed. As it          My fast-and-easy approach consist-       insulation between the 2x6s from
was, I still placed several supports in      ed of cutting slices with a chain saw      underneath and stapled Visquene
the middle of the expanse. A viable          where the notches were to be, and          underneath that. This, combined with
alternative here would be a concrete         then knocking them out with a sledge.      sod and snow on top, provides excel-
floor, which would have the extra            When the next log was to be fitted on      lent insulation.
advantage of acting like a solar battery     top, I would position it for the least        A rather large front overhang is a
to trap the sun’s heat during the day        amount of gap space, and occasionally      good idea for two reasons. It keeps
and radiate that heat back out at night.     I'd use the chain saw to improve the fit   moisture away from that part of the
Personally, however, I prefer the look       by removing bumps and other obstruc-       front wall that is above ground. And
and feel of wood flooring.                   tions. It is also important to alternate   it also cuts out hot summer sun, when
                                             the large and small ends of the logs or    the sun angle is high, while not inter-
Putting up log walls                         you will end up with one side of a         fering with the low-angle winter sun.
                                             house much higher than the other.          The winter after I finished the roof,
  When the subfloor was done, it was                                                    Alaska had the heaviest snowfall in 50
time for the logs. To move them to my
building site, I used the bulldozer
                                             Roofing the cabin                          years and many buildings in the area
                                                                                        collapsed, but my cabin pulled
again, first pulling them with a chain,        This design includes a shed-style        through just fine and I never had to
then using the blade to push them into       roof, which provides for maximum           shovel the roof the entire time. After
the pit. One of the advantages of my         sun exposure and is, incidentally, very    that, I felt more confident about my
underground design was that I didn’t         easy to build. To provide the slant,       little igloo.
have to lift any logs. Although it was       simply stop alternating the log ends          As I mentioned earlier, this roofing
occasionally awkward to position             and use the thicker ends exclusively       method was easy but a bit expensive.
them, this step was remarkably easy          toward the front of the cabin. The         A cheaper alternative might be pole
for me. Before pushing a log into the        front wall thus becomes higher than        roofing, with the poles covered first
pit, be sure to plan ahead how you will      the back wall. I began to build the        by chicken wire and then by concrete,
roll it into place! If it is balanced just   slant about halfway up the wall            which could be water-sealed. I was
right, it is truly amazing how a person      although, in retrospect, I realize I       looking at this method when the
can maneuver even a 2x40 foot log            could have used a bit more slope.          imminent snowfall forced my deci-
with one hand.                               Variations in the level at which you       sion.
  Joining the logs together is a little      stop alternating will also depend, of
like playing the guitar. You can do all      course, on the shape of your logs. The
right without knowing much, or you           more tapered they are, the longer you
                                                                                        The finishing touches
can spend a lifetime devoted to your         may wait to stop alternating log ends.       The next summer I returned from a
craft. While the more you know and             One of my prime motivating factors       honeymoon trip up the Alcan high-
do will always show in the results, an       in choosing the shed roof design was       way, and my bride Katie valiantly
airtight fit is simply not as necessary      the fact that winter was quickly           joined the project, helping me put alu-
with an earth-sheltered design. The          approaching. Since this design             minum siding along the sides of the
gaps between the logs can be filled          involved lumber, it was the most           cabin and fill in the pit with gravel.
with concrete (mixing it with sawdust        expensive part of the house. There are     After those two jobs were done, all
gives it better flexibility) or              alternative methods that would be          that was left were the little things—
store-bought log chinking (though this       cheaper, but they would also require       moving in a Franklin stove, installing
can be a bit pricey, if economy is an        much more skill than construction          windows, doors, floorboards, and so
issue). Since most of the outside walls      with lumber and plywood does. First,       on.
are covered with metal sheeting and          I placed a center beam across two            It’s been hard work, lots of fun, and
buried underground, small gaps do not        walls so that it traversed the middle of   in some ways a dream come true.
mean there will be holes into the out-       the cabin and gave support to the roof.    Future plans include a full-service
side air. More care should be taken          Then pairs of 2x6 boards were nailed       bathroom with hot and cold running
with the few logs that will not be cov-      together, much as when laying the          water and a combination solar- and


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                                      May/June 1994 Backwoods Home Magazine


steam-powered electrical system. I
have the plans now, and will write
more later to let you know how they
work out! ∆




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