Cob: Re; Casas Que Cantan

[SANCO Enterprises, LLC (Paul & Mary Salas)]

List Friends,

At Mark Piepkorn's urging, I'm going to reply about Obregon and how down
Mexico way things are definitely a little different. I had stopped at the
Black Range Lodge in Kingston, NM to visit Mark before heading south and as
usual Mark was away doing other things.  I met TLS Managing Editor Catherine
Wanek and her husband Peter and to cut to the chase, I spent the night at
the lodge. Catherine and I left for Obregon the following morning, Monday
Jan 10th.

I had informed Bill Steen that I was not going to participate in the
workshops at Xochitl and would instead preferred to assist in the
installation of the pumps I had designed and built for the project.
Catherine Wanek was there to film and document the work, therefore what
follows is a synopsis of what I participated in on a limited basis over the
course of one week.

When we arrived, one house was already in the rough earth plaster stage and
the foundation was being prepared for another house near by. Bill and Athena
Steen have done a remarkable job helping the local people build their own
housing at very little monetary cost and lots of manual labor. Here are a
few of the interesting and innovative things that the Steen's have
introduced in Mexico and could be applied elsewhere.

Foundation
The foundation is based on the old Spanish Tapia method of combining stones
and lime cement to form an "on grade" stem wall.  The form materials were
very crude pieces of lumber about 14" high and bale width.  Large stones
were placed at the bottom followed by infill with smaller stones. The
concept is to use as little cement as possible, therefore each course of
stone should be tightly packed.  The mix design consisted of pit run coarse
sand with stones up to 1",  local hydrated line and local cement. The mixing
area was the center of the home that was to be constructed. The mix was
started with a layer of sand approximately 6 feet in diameter and 4 inches
thick, followed by 2 sacks of lime and a sack of cement and the processes
was continued 3 more times. The entire mound was then dry mixed with shovels
to obtain a even distribution of the materials. The mound was then flattened
out and a well made in the center. About 30 gallons of water were added and
the mix was allowed to soak for 30 minutes. The locals, accustomed to mixing
in this manner, added additional water as hydration took place. They seemed
to sense when the mix appeared too dry.  After a 45 minute lapse, the mound
was then turned over onto itself and mixed  until a #4 slump was achieved.
The wet cement was then layered over the first course of stones.  Additional
layers of stone and cement followed until the stem wall was completed.

Since the straw bale walls were going to be load bearing, tie downs were
provided in the stem wall at the door opening and spaced about 6 feet apart
around the perimeter.  The tie down consisted of #4 steel wire first formed
into a circle and the ends looped.  The circle was then folded in half  to
form a "U" with a 4 inch space at each end between the loops.  The tie downs
were placed at the bottom of the stem wall and protruded about 4 inches
above the height of the stem wall.

Wall Raising
The bales were of very poor quality and tied with steel wire.  The bales
were stacked in the conventional method and included making partial bales
where required.  The bale widths and lengths were very inconsistent and
required selecting appropriate sizes to fit properly.  When the wall was at
the 6 foot height, "carrizo cane" was used to provide external pinning for
the wall. Carrizo looks like bamboo but is not related.  It grows locally
and is very strong.  This method of pinning has served the Steen's extremely
well especially since the bales are less than optimum.  The carrizo is
placed on both sides of the wall and twine is placed in a bale needle and
looped back and tied so that both sides are tied together.  The best
location for placement of the tie is between bale courses as it seems to
obtain a much tighter attachment.  The carrizo is placed about 3 feet on
center around the perimeter and tied every other course.  The length of the
carrizo is allowed to remain as found and are cut to length after the raters
are installed.

Earth Render
It's interesting that earth-straw plastering commences immediately after the
first few courses of  carrizo are tied to the walls.  The rough plaster mix
consists of very long straw and clay-soil. The finish plaster is made from
finely chopped straw and clay-soil.  Because 30 people were at work,
progress was very rapid.

When the wall was at full height, round logs about 6 inches in diameter were
used for the top plate on the bales.  #4 steel wire was tied to the loops in
the stem wall and extended 8 inches above the top plate log.  The wires, one
from each side of the wall were then twisted together to compress the bales.
Since the plaster was still very wet, there was no ill -effect on the render
during compression.

Roof
Rough sawn 2 x 6 lumber was used for roof rafters spaced about 3 feet apart.
A string line was used to gage height and wooden shims used to trim the
rafters to the correct height. The rafters were nailed to the top plate with
20 p nails.  The spaces between the bales and the top of the rafters were
filled in with straw rich adobe blocks which had been made in advance.
These were mudded in, then plastered along with the wall. Carrizo was used
as latillas and were tightly coursed perpendicular to the rafters. When the
carrizo latillas were completed, the external pins were tied and cut to
length. Long straw-clay was applied over the carrizo on the roof.  It is
important to ensure that the carrizo is very tight because the carrizo is
exposed to the interior. The earth render is then molded and shaped in the
traditional manner to cover the rafter ends.  On one house, the straw rich
adobe-like blocks were used to provide a parapet and on another, steel
pro-panel roofing was installed. Those homes that do not have steel roofs
have a very thick layer of straw-clay as the final covering.  Water
catchment is important in this arid area.

Windows and Doors
The window and door openings are reinforced with carrizo and the rough
opening is rough plastered.  Steel framed windows and doors are installed
and mortared with straw-clay similar to the other wall sections. Earthen
floors are typical.

Water Well
The water well was to have been completed prior to our arrival and due to
extremely difficult digging was not completed when I departed on Jan 16th.
The well was being hand dug and required the use of hammer and chisel. the
work as very hard and limited to one person at a time in the hole.  At about
9  meters, water was found, however an additional meter or more was required
to ensure that the well would not go dry in the summer.

Gerardo Sastras, a city of Obregon Public Works Manager, was extremely
helpful in allowing me the use of his shop facilities to complete the
assembly of the pump system.  We were able to test the pumps to ensure that
they would have a working system when the well hole was completed.  We
disassembled the pump after testing and Gerardo assured me that he would
personally assisting the families in the installation of the pump. Because
the pumps were made from commonly available materials, I must have conducted
20 or more instructional meetings for various groups outside the families we
were helping.  The key here is to tech and inform and allow them to do for
themselves. I feel confident that several more wells and pumps will be built
in the near future.  It was refreshing to see in their faces when they
grasped the concept and were able to apply it to materials they have at
hand.  Sounds like the fish story doesn't it?

Participants came from Japan, Canada, Mexico and throughout the USA.
Experience levels also covered the full spectrum as well. Marks comment
about the building movement encompassing a much broader group than those who
participate on the list is evident by those he named as well as those who
work independently.  I took an informal poll of the participants and most,
85%, do not monitor or participate on any list. Interesting to say the
least.

Paul Salas
General Manager
SANCO Enterprises, LLC
P.O. Box 45741
Rio Rancho, NM 87174
(505)  238-1485