Dirt Floors in Earthen Construction

A lot of people associate the phrase “earthen construction” with the material used to build walls- adobe, rammed earth, CEB.

But the oldest form of earthen construction is not actually the material used for the walls of a structure but the floors.

Dirt floors have been around since humans first created enclosed structures to protect themselves from the elements. Even today, dirt floors are common in many less developed parts of the world.

Until the middle of the 20th century, dirt floors were not an uncommon choice in rural areas of the United States, especially in warmer climates where protection from the cold is not an issue.

Now, dirt floors are making a comeback in some circles. They offer some key advantages:

  • dirt can be sourced locally virtually everywhere in the world
  • dirt is cheap, as in dirt cheap
  • dirt is a good insulator
  • repairs are easy
  • dirt is firm, but not as unyielding as concrete or tile
  • dirt floors can contain embedded hydronic heating systems

Properly done, earthen floors are an attractive, comfortable choice for homes, and new techniques and materials are making it possible to have good looking, long lasting floors made of earth.

The photo below shows an earthen floor under construction. This floor currently has a roughly five inch thick layer of earth mixed with roughly ten percent cement, embedded with straw as a binding agent to prevent cracks. The top two inches contains shredded straw for a finer finish.

Once this house is enclosed, another thin layer of earth will be poured on top of the existing material to level and smooth the surface. It will then be sanded smooth and sealed with linseed oil. Finally, a layer of beeswax will be applied, and the floor will be polished to a shine. At the end of the process, it should have a sheen that looks like polished leather.

This floor also has an embedded hydronic heat system in it as a backup for the three fireplaces that act as a primary heat source. Since this house is a passive solar house made of CEB with large windows and trombe walls on the southern exposure, heating needs are expected to be relatively modest.

dirt floors under construction