Earthen Floors
Also known as poured
adobe or cob, earthen floors embody almost all of the best
attributes of ecological building. They are made of widely
available, cheap, local materials--clay, gravel, and straw. They
work perfectly with passive solar designs, adding thermal mass to
the inside of a building where it can store heat accumulated from
the sun. They are solid underfoot, but softer than concrete or
stone. They are also warmer to the touch than concrete and stone,
and are ideal to use with radiant floor heating. But best of all,
they are beautiful and comfortable to walk on. Sealed with multiple
coats of natural oils and then a top coat of wax or resin, their
finish color is the same as the wet clay soil they're made from.
Chopped straw can be added to the final layer to add depth and
texture to the final appearance. Similarly, different colored clays
or tints can be used for the final coat to allow a wide range of
finish colors.
For buildings without a basement, standard conventional building
practice is to pour a concrete slab on grade. But as a building
material, concrete has several critical disadvantages. First of
all, its manufacture is extremely energy intensive, requiring
massive amounts of fossil fuels. Because so much of it is produced
globally, its production accounts for 7-10% of all greenhouse gases
released into the atmosphere each year. As a flooring material,
concrete is extremely hard, and therefore very hard on knee and hip
joints, which evolved to handle the stresses of walking and running
on soft earth. A more ecologically sound foundation is a rubble
trench topped by a grade beam. This ancient method was introduced
to modern building practice in the United States by Frank Lloyd
Wright. Inside the beam, layers of drainage rock, gravel, and clay
are built up to create an earthen floor. The same foundation can
also be used with floors of wood, stone, tile, or brick.
