HG: SustainAbility Column March 21, 2009
An ancient building method with a new twist is cropping up in Western Colorado and even in Mesa County.
For thousands of years, people have constructed buildings from the earth, and with the help of modern machinery this art has culminated in blocks of compressed earth.
Dozens of homes have been built with Earth blocks in Durango and Pagosa Springs. In Pagosa Springs, the local Habitat for Humanity erected homes using Earth blocks.
David Ellinwood is a farmer and rancher in New Liberty, north of Mack. Six years ago he purchased mixing and manufacturing equipment to create natural earthen blocks. Ellinwood calls his business Eco-Block Adobe and has provided his services as needed since then.
In this area, blocks made by Ellinwood’s machine were used in a home in Molina and a shop in Fruita. He has two more projects on tap for this summer, homes on Little Park Road and in
The main ingredient in Earth blocks is local dirt, which in our case is mainly clay. Ellinwood combines the dirt with gravel fines, a byproduct from crushing gravel. This is mixed in a modified continuous mixer with 7 percent Portland cement to stabilize the blocks and a small amount of water.
Sometimes the dirt for making the blocks can come from the building site itself. If the home has a full basement, there is usually enough dirt at the site. When there are just footers, Ellinwood shops locally for the clay and other ingredients he needs.
The press used to form the blocks is made by Advanced Earthen Construction Technologies Inc. It runs on diesel and employs intense hydraulic pressure to produce as many as 350 blocks per hour.
Ellinwood said his record is about 1,500 10 by 4 by 14-inch blocks in one six-hour period. The cured Earth blocks are much stronger than required by code for above ground construction, with compression strength varying from 700 to 1,000 pounds per square inch.
Once the blocks are pressed, Ellinwood likes to wrap them in black plastic and allow them to cure for about 20 days. The finished product is ready for building with help from mud slurry made from a finer version of the dirt mixture and water.
Using earthen blocks as a building material is sustainable for many reasons. Producing Earth blocks involves a very small amount of embodied energy. The ingredients are local and the blocks are usually produced on or near the building site, reducing transportation costs. Use of timber, concrete and other resources is greatly reduced.
Well-planned and designed homes made from Earth blocks are very energy efficient. “The key is thermal mass,” Ellinwood said.
The walls are 10 or 14 inches thick, depending on how the bricks are placed. The homes stay warmer in the winter and cooler in the summer.
The homes are also healthy with breathable walls allowing for natural humidity control. Many people decide to build with Earth blocks because of chemical sensitivities.
The building material is also fireproof and absorbs sound creating a quiet home. Longevity is another great feature of Earth Block homes. Ellinwood said the roof would fall in long before the adobe blocks will give out.
Structures made from earth, such as the Great Wall of China, have been known to stand for thousands of years.
You can finish the exterior of the house with stucco, plaster or leave the walls natural with just a sealer, depending on local codes. Interior walls can be made any color with mud or lime plaster or even a lime wash. There is a woman in Moab who specializes in finishing interior walls in Earth Block homes, Ellinwood said.
Working with Earth blocks as a building material requires extra concrete in the foundation because the blocks are heavy. You also need to use bond beams between floors and under the roof. A bond beam is a concrete ridge cap made to seal in the blocks.
Building with Earth blocks takes some planning, and good engineering and design are essential. The home should be oriented on the building site to take advantage of the winter sun but not bake in the rays of summer. This will reduce heating, cooling and lighting costs.
You can hire a contractor or do the building yourself. It is easy to learn how to stack the blocks, but there is a lot to know about building with Earth blocks. A four- or five-person crew works to put up all the walls at the same time, starting from the corners and working in.
Ellinwood recommended a class taught by experts in New Mexico. For more information go to http://www.adobebuilder.com/solaradobe-school-curriculum.html.
According to Ellinwood, adobe architects are well worth a fee because they will work with local building departments and design great homes.