What is rammed earth?
Rammed earth is an ancient building process; a moistened earthen mix of aggregate sand, clay and sometimes cement is placed into forms and compacted or "rammed" in layers. After removing the forms you are left with a free standing monolithic earthen wall. Some compare it to the layering on the side of cliffs.
Why use rammed earth?
Rammed earth offers a sense of security and serenity due to its massive walls. It has great thermal mass which keeps you cool in the summer and warm in the winter, cutting back on heating and cooling bills. For example, in Edgewood, New Mexico, where we live we conducted an experiment with a contractor, comparing his new frame home with our rammed earth home. The experiment was to see how high the interior temperature of the homes would get during the summer without air conditioning. The outside temperature was 96 degrees; the inside of his home rose to 92 degrees, but the inside of our home did not go above 76 degrees. A considerable difference!
What does it look like when it's finished?
There are many finished looks to rammed earth.
It can be left as is, with the application of a clear sealer which lets you observe the natural beauty and color of the wall.
The walls may be sandblasted, which tones down the layers, adds a rougher texture and creates a more rustic look.
Cement and mud plasters may be applied to the finished walls.
The walls can also be stained or painted.
How is the electrical wiring installed?
We use metal masonry boxes with ¾" conduit usually running out the top of the walls. The electrician then comes in pulls the wire and runs it through the attic.
How do you install the plumbing?
We run plumbing vents but not pressurized lines in our walls. This enables easy maintenance.
Is it difficult to get building permits?
Permitting is not a problem. New Mexico has its own rammed earth code.
Do I have to seal the walls?
It is highly recommended that the walls be sealed to prevent efflorescence, water damage and dusting. A breathable sealer with bonding agents and water repellent works best. We recommend Ram Seal.
What about financing and insurance?
While many banks are not familiar with rammed earth, once educated they typically are willing to loan money for our projects.
Insurance is also relatively easy to obtain.
This 2400 square foot contemporary style home is nestled in a valley in Placitas. The two foot thick walls range from 8-9' in height. Still to come, a rammed earth gable will be added to the living room wall.