People have been building with mud for thousands of years. Taos Pueblo in Taos, New Mexico, where I live, was built of mud by hand and has been continually inhabited for over 1000 years. Other indigenous people of this region were building with mud in 750 AD. Adobe buildings in Iran date back to 500 BC.
Structures can be made of bricks, cob or rammed earth, and building with adobe is an easy do-it-yourself project. You can get creative and cut costs! Consider going to some workshops or offering to work with an adobe contractor to get educated.
I’ll cover bricks here. Cob and rammed earth building will come soon!
How adobe bricks are made
The residents of Taos Pueblo built their pueblo by putting handfuls of mud on top of each other (cob). The Spaniards came in the 1600s, and they taught the Pueblo people how to make adobe bricks, which is very simple.
A thick mixture of clay (30-50%), sand, water and straw is packed into rectangular forms, the forms are removed and the bricks are allowed to cure for a few days. The size of the form determines wall thickness. The thicker the wall is, the cooler the home is in summer. Thick walls also make for deep windowsills, and I don’t know anyone who does not like a deep windowsill!
Adobe bricks when green building in termperate zones
Sometimes bricks are stabilized with cement or asphalt, especially if moisture is a potential problem. This allows adobe to be used in many climates.
Suggestions for building with mud in wet regions:
- The foundation wall should extend above the ground 8-12″.
- Don’t build in low-lying areas where water puddles.
- A pitched roof with large overhangs will keep rain off.
- Concrete or synthetic stucco will protect the walls.
Adobe bricks; “Pueblo style”
When building, bricks are stacked like regular red bricks, off-center for stability. Arches can be built over a form, and bricks can also be used to create lintels over windows and doors.
The outside of an adobe building must be plastered to protect the bricks and joints. Originally it was done with mud, and the St Francis Church that Georgia O’Keeffe made famous in her paintings, is re-plastered by the congregation annually. It is a labor-intensive process, but not when the whole community helps.
Modern day plaster is colored synthetic or concrete stucco that never needs to be re-plastered. If mud plaster is used, it should be stabilized for water resistance. This allows adobe to be a universal building material.
Adobe homes are in high demand here in New Mexico. It’s called ‘Pueblo style’ and imitates the northern pueblos with adobe walls and a flat roof. An adobe home will sell faster than a stick-built home, but adobe is not the most efficient material.
Adobe bricks and insulation
Adobe is not a good insulator. It actually extends the heating season, because it keeps buildings very cool, unless it is insulated. Here, our building code requires that the exterior of an adobe home be insulated with 2” of rigid foam, then plastered. That way, the heat it collects in winter stays in the house. New adobe homes are much easier to heat than the old ones someone’s great grandfather built by hand. If adobe is not insulated, the heating season is extended – it starts earlier in fall and goes later in spring.
It takes a few days of heating to get adobe warm inside. Once it’s warm, it does retain the heat, keeping energy bills low. In summer, it stores heat to keep the house cool. I lived in an adobe house for a few years, and it was always 70 inside in summer. In winter, the walls by the wood stove were warm in the morning, long after the fire had gone out. That is adobe acting as thermal mass.
Adobe homes and passive solar
Adobe is very effective as thermal mass in a passive solar home. An adobe wall collects heat from the sun, and after dark, it slowly releases the heat back into the room. This has to do with physics and the temperature difference of the wall and the air, but I won’t go into that here. Take my word that an adobe wall as thermal mass has a nice even, radiant heat to it, even on the coldest nights.
Adobe also has excellent acoustics. I could not hear the phone ring two rooms away, as the adobe absorbed the sound. Because of this feature, an adobe home is quiet with a sense of privacy.
Abobe homes: green building, green living
Adobe is eco-friendly, too, because it is a local material. I know many people that have built homes with bricks made from the soil on their land. Contractors can buy bricks locally, which means materials are not transported long distances. And what is more green that building with earth?! An old adobe home can deteriorate and, literally, go back from whence it came.
For thousands of years, adobe has been used as a green building material. The fact that those buildings are still in use says a lot about its excellent qualities of keeping a building cool in hot climates, being durable and being easily accessible.
Stay tuned for upcoming posts on cob homes and construction.