Natural Building 101: How To Make an Earthen or Adobe Floor

When mention of an “earthen floor” is made, one might imagine a dusty, drab dirt floor. Earthen floors are far from this, however; instead they are very elegant, durable, inexpensive, and ecologically sustainable solutions to a typical floor installation. They are varied in construction, but the idea and ingredients are essentially the same across the board. Earthen (or adobe) floors are poured or compacted combinations of sand, clay, straw, and sometimes crushed rock, with pleasantly smooth surfaces resistant to wear and tear, and capable of storing heat from the sun.

There is no one way to construct an earthen floor. They are a natural option for straw bale or cob buildings, but they can even be installed on concrete slabs or preexisting wood floors, as along as the framework is strong enough to support the heavy weight of many buckets full of earthen material.

How to make an earthen floor

A typical earthen floor might include 70% sand, 30% clay, with lots of chopped straw for tensile strength. Oftentimes, they are constructed of two or three layers. My own earthen floor is (or will be, I should say) composed of two layers, the base layer composed of sand and clay at a 3:1 ratio, with handfuls of long straw mixed in for extra strength. (See photo to the right!) This sublayer is 2.5″ thick. Once it is dry, the final layer will be installed and smoothed with a trowel, composed of a similar sand to clay ratio, but mixed with very short chopped straw. The sand will be sifted and the clay will be sieved to remove larger particles.

Earthen floors in suburban homes

Some homeowners have even installed earthen floors in their suburban homes, influenced by the low impact nature of an earthen floor. The New York Times has a nice article detailing one family’s earthen floor installation experience. Earth is an environmentally friendly alternative to hardwood flooring (which requires lots of lumber typically shipped over great distances) and carpet (which may offgas dangerous toxins like formaldehyde), making it an appealing option for more eco-conscious homeowners.

Earthen Floor Alternative: Metal Buildings

Benefits of an earthen floor

Earthen floors can be very easily made using local materials, and are a common sight in traditional housing all over the globe. Materials can be found locally, as close as the ground underneath your feet.

Notably, they are also an excellent option for passive solar homes, due to their thermal mass. For example, the heat of the sun striking the floor in the wintertime will be stored in the mass of the floor, making for a pleasantly warm surface. This heat can also slowly radiate into the living space over time.

For more information on earthen floors and how to make them, check out the following websites.

  • New York Times: Down and Dirty
  • Earthen floors at House Alive!
  • Making an earthen floor at Dirt Cheap Builder
  • How to pour a rammed earth floor / adobe floor at Dancing Rabbit

(Image credit: flickr via tylerwawa)