Our adventure in earth construction began ten years ago in the aisle of a
bookstore in New York City. My husband and I had just returned from a trip
to Park City, Utah, where we visited a recently completed straw bale home.
We were so taken with both the use of natural materials and the interior
aesthetics that could be achieved that we decided to research alternative
building methods.
A designer and builder passionate about architecture, my
husband had worked on several sustainable residential projects and had come
away with the impression that sustainable building required finances we
didn’t have. We were, at that time, green novices, doing our part in
preserving the planet by making sure our recyclables were sorted, walking to
work, and avoiding plastic whenever possible. But we were living, working,
and (as I like to say) “renting” a hectic life in one of the fastest-paced
cities in the world, dreaming all the while of building our own home. It was
clear that our lifestyle, habits, and finances were not in line with our
objectives. We needed a drastic change.
Then my husband spotted a book on the work of the late Egyptian architect
Hassan Fathy, whose revival of mud-brick building techniques and use of
local materials not only helped shape communal architecture in third world
countries but continues to influence the use of earth as a modern building
material in the developed world. According to Fathy, building with earth was
both environmentally and socially responsible and attainable for all.
Pouring over the pages of earth walls, vaulted ceilings, pierced
decorative details, and air chimneys – all constructed with dirt and water –
we knew the seed had been planted. The results were not only beautiful, but
they spoke to our goal of living responsibly within our budget. More books
on earth building began to find their way onto our nightstands, and
preliminary sketches of house plans, drawn in the margins of newspapers and
on the backs of grocery receipts, were carefully filed into a folder we
called “A Turning of the Soil,” symbolizing both our dream of building an
earth house and our desire to start a more conscientious, purposeful life.
As often happens with important life projects, momentum took over. My
husband, a French native, had visited Senegal, West Africa many times and
had always felt drawn to the people and place. We had purchased land there
some years before as a place to build a retirement house. When the financial
crisis hit the United States in 2008, we made an instinctive decision to
step up our plans and move to Africa with our two small children, build our
earth house, and realize a simple life closely connected to Nature. Two and
a half years later, through lots of trial and error, we now live in a 2,500
square foot home built with earth excavated from our property (the hole now
a lap pool) and powered by wind and sun. The walls of our house were built
using the earth under our feet, water from our well, a few pieces of plywood
and iron, and eighteen pairs of hands, including our own. Our children, then
three and four, learned to make earth bricks by throwing mud into wood
frames and watching the sun turn them into usable bricks, which they then
helped lay.
We combined two types of construction: rammed earth for the two-foot
thick walls, and earth bricks for the arched windows and doorways. Both of
these methods allow for relatively quick construction and no “baking” time,
as is necessary with adobe or cob construction, where the materials are
cured. Rammed earth or “pise de terre” is the successive layering of a
prepared earth mixture into wooden formwork. Each layer is approximately
fifteen centimeters (six inches) deep and is manually compacted with a large
wooden (or pneumatic) ram to approximately fifty percent of its original
thickness, allowing for minimal micro-fissures that may trap moisture.
Because the compacted earth is immediately self-supporting, as sections of
walls are completed the frames can be moved vertically or horizontally to
either dove-tail or butt against a new section.
While the water content for rammed earth is typically low, mud bricks
require a more humid mixture, which is poured into wooden frames and left to
dry for one day in the sun, then laid horizontally following the curve of a
metal frame and mortared with additional mud. We constructed two iron frames
of different sizes, one for all the half-moon windows and one for the curved
doors. To complete the walls of the main living area (two bedrooms, a living
room, kitchen, bath, and separate classroom) took us six months, using only
manual labor. Apart from a bulldozer to excavate the original quantity of
earth needed to build the house, no machinery was used on the project.
|
Earth construction has low carbon emissions, high thermal
mass, good air quality, excellent durability, uses local
materials, is recyclable, allows for a creative design, and can be
owner built. |
Because Senegal has a tropical climate with significant rainfall, we
needed to protect the walls we worked so hard to build. During the dry
season, the sun continues to cure the earth walls, with optimal
stabilization occurring after three years of exposure. In the interim, they
need special attention. Although earth buildings are never completely
waterproof, they can be made water-resistant by adding a natural polymer
mixed with earth as a final layer. We experimented with many different
formulas, including natural soap, shea butter, vegetable oil, even okra and
rice starch, which contain a natural glue-like substance. Our kids
participated in our laboratory; a section of the back exterior wall which
shows the trials of all our formulas. After each square foot application had
dried, we would throw buckets of water on the wall and watch for the
reaction. Although okra and shea butter proved equally effective, we didn’t
have the quantity necessary to cover the entire surface. In the end,
vegetable oil created the most consistent, available barrier and two coats
were painted on all the exterior walls. The experiment section now looks
like a patchwork quilt, just another aspect of our hand-made house.
Next came the roof and with it, a lesson learned. The original was made
of earth and employed Nubian vaults, which are constructed without frames.
Earth bricks are laid following the arc of a suspended metal chain, a
technique revived by Fathy in the 1940s.
Several days after the roof was completed, which happened to coincide
with the onset of the rainy season, we returned to the United States to
visit with family and arrange transport of our belongings. When we returned
to Senegal six weeks later to move into our house, sections of the walls and
roof had been severely damaged by the rain. The tarps we had secured in
place to protect the newly constructed roof had blown away, exposing the
earth to the elements. We learned that we were in the midst of one of the
worst rainy seasons in fifteen years. So it was back to the drawing board in
a rented hotel room.
French masons used to say that any house built with earth needed sturdy
boots and a good hat to weather the storm. After much additional research
and consideration, we decided to tear down what remained of the existing
vaulted roof and replace it with a flat cement roof which would leave no
room for uncertainty. The considerable overhang (two feet) would not only
reduce rain flow to the walls but allow us to collect rainwater in reserve
for the dry season. It was a difficult decision to make as our purist
tendencies gave way to reason. As an environmental offset for the cement
roof, this year we will be planting an organic roof garden, using the
available space to provide food for our family while at the same time
creating a micro-climate to cool the rooftop. During our research, we
learned that due to the mass of the walls, they can support multiple floors,
leaving open the possibility to build additional rooms in the future.
Earth walls provide natural insulation, adjusting to heat, humidity,
wind, and rain. They regulate the interior temperature by absorbing excess
moisture in the air and releasing it when the air is too dry. As our walls
are two feet thick, they keep the interior of the house very cool.
Conversely, the density, thickness, and thermal conductivity of rammed earth
make it a particularly suitable material for passive heat in cooler
climates. We added natural terra cotta tile floors, which also help keep the
rooms cool. To augment air circulation, each room was constructed with a
light well, which also serves as an air chimney. Modernizing an ancient
technique, we installed large square openings in the ceiling covered by a UV
filtering piece of glass that can be completely closed (for when it rains)
or opened to varying degrees for ventilation. The openings are placed
strategically to maximize the effect of dominant winds, acting as a vacuum,
carrying heat up and out.
Because we wanted our project to be completely off the grid, we built our
own wind turbine, installed solar panels, dug a well, and use a dry toilet
system. Our house is still an ongoing project, as is our effort to train
local masons in earth techniques. But the space we built together has
connected us to Nature, each other, our community, and the principles of
living responsibly for ourselves and the environment – all within a modern
earth structure.
To read the rest of this article, which includes more
information about earth as a building material, advantages and disadvantages,
building codes, resources, and more, please
purchase the relevant back issue. To read more articles like this,
please
subscribe.
Ellen Rowland is an American living in Senegal, W. Africa in an
off-the-grid earth house she helped build with her husband and two young
children. She is a writer of sustainable issues, fiction, humor, and poetry
and is currently working on a book about her experiences in sustainable
family living. A lover of all things edible and a passionate cook, she is
also working with several women in her village to produce a cookbook of
local flavors and culinary customs.
