What is Adobe? Sustainable and Energy Efficient

Summary of Preservation Brief 5

Adobe bricks being formed
Adobe bricks being formed. Photo by M Timothy O'Keefe/Photographer's Choice RF Collection/Getty Images

Adobe is an ancient building material, essentially a dried mud brick, usually made with tightly compacted earth, clay, and straw, formed into "bricks" and dried or baked in the sun. Traditional to the American Southwest, adobe bricks have been used around the world, including ancient Egypt and the Middle East. Construction methods and the composition of the adobe will vary according to climate and local customs.

Although the word is often used to describe an architectural style, adobe is actually a building material. An adobe wall is load bearing, self-sustaining, and provides natural energy efficiency. Sometimes an asphalt emulsion is added to help waterproof the adobe bricks. A mixture of Portland cement and lime may also be added, but these materials will add to the cost. In parts of Latin America, fermented cactus juice is used for waterproofing.

About the word adobe:

Pronounce adobe with the accent on the second syllable and pronounce the last letter: ah-DOE-bee

Adobe is the term widely used in the southwestern United States and Spanish speaking countries. Unlike many architecture words, adobe does not originate in Greece or Italy. Meaning "the brick," the word derives from Arabic and Egyptian and has also been seen in ancient hieroglyphics. It comes to the United States via Spain.

Materials Similar to Adobe:

Compressed Earth Blocks (CEBs) resemble adobe, except they usually do not contain straw or asphalt, and they generally are more uniform in size and shape.

When adobe is NOT formed into bricks, it's called puddled adobe, and is used like the mud material in cob houses.

See the Natural Building Blog of Dr. Owen Geiger for photos of puddled adobe. Dr. Geiger contends that Native Americans used puddled adobe before the Spanish introduced adobe brick-making methods.

Architecture Associated with Adobe:

About Preservation Brief 5:

The National Park Service of the U.S. Department of the Interior published Preservation of Historic Adobe Buildings in August 1978. What follows is a summary of the Brief, with links to sections of the online version. Direct quotes are from Preservation Brief 5.

What is Adobe?

"Unbaked adobe bricks consisted of sand, sometimes gravel, clay, water, and often straw or grass mixed together by hand, formed in wooden molds, and dried by the sun."

  • its strength varies with its changing water content
  • naturally unstable, but may be stabilized with "cement, asphalt. and/or bituminous materials"
  • commercial adobe is often kiln-dried
  • "it must dry in the open air for a month or more before it can be used"

Adobe Construction Techniques:

True adobe bricks must be assembled with a mud mortar of properties similar to the adobe. You can't use cement mortar because it's too hard (i.e., "the mortars are stronger than the adobe").

Foundations are often constructed of brick or stone. Walls are load-bearing and thick, sometimes braced with buttresses. Roofs are wooden, usually flat, and stabilized by the familiar vigas projecting through the adobe walls.

After the railroads enabled the transport of building materials to the American Southwest, other roof types (e.g., hipped roofs) began to appear atop adobe brick.

Traditional Surface Coatings:

Adobe brick walls, once in place, are usually protected by applying a variety of substance. Since adobe is an ancient building method, traditional surface coatings may include substance that seem odd to us today—for example, "fresh animal blood." More common siding include:

  • mud plaster (mixture of "clay, sand, water, and straw or grass")
  • lime plaster (Mixture of "lime, sand, and water" is harder than mud, but more prone to cracking
  • whitewash (consisting of "ground gypsum rock, water, and clay")
  • stucco, a relatively "new" form of adobe siding, cement stucco does not stick to traditional ("unfired") adobe bricks, so wire mesh must be used

    What To Do When Adobe Goes Bad:

    Like all architecture, construction materials and methods of building have a shelf-life. Eventually, adobe bricks, surface coverings, and/or roofing deteriorate and must be repaired. Follow these general rules:

    1. Unless you're a professional, don't try to fix it yourself.
    2. Repair any problem sources before anything else.
    3. For repairs, use the same materials and building methods that were used to build the original structure. "The problems created by introducing dissimilar replacement materials may cause problems far exceeding those which deteriorated the adobe in the first place."

    Sources of Deterioration:

    Problems usually have more than one source, but the most common are these:

    • Poor building, design, and engineering techniques were used.
    • Too much rainwater, ground water, or watering of surrounding vegetation.
    • Wind erosion from windblown sand.
    • Harboring plants or insects within the adobe walls.
    • Previous repairs with incompatible building materials.

    Repairing and Maintaining Adobe:

    Patching and repairing adobe bricks, mortar, rotting or insect-ridden wood, roofs, and surfacing agents should be handled by seasoned professionals, who will know to use matching construction materials.

    Maintenance:

    Constant monitoring of deterioration sources, including the breakdown of mechanical systems like leaky plumping, is the most important part of maintaining an adobe structure. "It is the nature of adobe buildings to deteriorate," we are told in Preservation Brief 10, so careful observation of "subtle changes and performing maintenance on a regular basis is a policy which cannot be over emphasized."

    Summary, References, and Reading List:

    "Adobe is a formed-earth material, a little stronger perhaps than the soil itself, but a material whose nature is to deteriorate. The preservation of historic adobe buildings, then, is a broader and more complex problem than most people realize. The propensity of adobe to deteriorate is a natural, ongoing process....Competent preservation and maintenance of historic adobe buildings in the American Southwest must (1) accept the adobe material and its natural deterioration, (2) understand the building as a system, and (3) understand the forces of nature which seek to return the building to its original state."

    Learn More:

    • Making the Adobe Brick by Eugene H. Boudreau, 1972
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    • Early Architecture in New Mexico by Bainbridge Bunting, University of New Mexico Press, 1976
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    • Adobe: Build It Yourself by Paul Graham McHenry, Jr., University of Arizona Press, 1985
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    Notes: Headings are linked to the complete section of Preservation Brief 5, August 1978, on the NPS website. Quotations are from that online version. An 8-page, black and white PDF is also available.