Adobe building material properties

In size adobe bricks vary from about 4x8x12" small adobe bricks to much larger sizes. Some adobe builders use wider rectangular adobe such as New Zealand's Solid Earth builders providing square xxmm building adob e bricks along with larger xxmm corner adobe bricks. Shaped and compacted earth was used as early as B. Bowen Adobe construction has been used world wide since pre-historic times to build structural walls and floors, arches, towers, and for Arizona's Anasazi, grain storage facilites mid-way up the walls of the Grand Canyon BC - AD.

Adobe structures that are protected from the weather can survive for more than years. Below: an Anasazi corn storage crib using stone and adobe in the Grand Canyon, photographed by the author in July, No more than half the clay content should be expansive clays, with the remainder non-expansive illite or kaolinite.

Too much expansive clay results in uneven drying through the brick, resulting in cracking, while too much kaolinite will make a weak brick. Typically the soils of the Southwest United States, where such construction has been widely used, are an adequate composition.

Below: this adobe house was named for Maria Navarette Cordova whose family acquired the home in Above: remains of a 19th century adobe structure remaining outside of Mineral de Pozos, nee Mineral de San Pedro de los Pozos, a silver mining center in Guanajuato, Mexico.

At its peak, Pozos was populated by silver, copper, zinc, and mercury mine workers and was home to about 80, people. Pozos was more-recently a ghost town and currently a small but growing tourist destination. When Europeans arrived at Pozos wells in the area had been settled for centuries by Chichimecas and Huachichiles and their ancestors.

But the adobe durability story changes when there is a roof or wall leak, or where surface runoff or rain splash-up wear the bottom of an adobe wall.

Adobe structures are usually coated on the exterior and interior with a stucco mixture of cement, plaster or similar substances. Stucco on adobe suffers different problems from stucco systems on framed walls. On adobe, the most common stucco coating failure I see is adhesion loss, usually when rain water penetrates the stucco wall coating. That may explain the loss of the stucco coating on the adobe wall of the adobe and stone structure in Jalpan, Queretaro, Mexico, shown in our preceding photo.

La Casa Cordova includes remaining portions of one of the oldest still-standing structures in Tucson, believed to have been built before the Gadsen Purchase in Photo below: an antique adobe structural wall with cement stucco coating in Oxaca, Mexico.

I first visited this building in Oxaca I visited it again, finding it in its present condition in In the west Texas and Tucson areas, "saguaro" cactus ribs were used to span between vigas. After railroad transportation arrived in most areas, sawn boards and planks, much like roof sheathing, became available and was often used in lateth and earlyth century buildings or for repairs to earlier ones. Next cedar twigs, plant fibers, or fabric were placed on top of the poles or planks.

These served as a lathing on which the 6 or more inches of adobe earth was compacted. If planks were used, twigs were not necessary. A coating of adobe mud was then applied overall. The flat roofs were sloped somewhat toward drains of hollowed logs called "canales," or "gargolas" , tile, or sheet metal that projected through the parapet walls.

Gable and hipped roofs became increasingly popular in adobe buildings in the 19th and 20th centuries. For example, roof tiles were widely used in southern California. Although the railroad brought in some wooden shingles and some terra cotta, sheet metal roofing was the prevalent material for roofs in New Mexico.

Historically, flooring materials were placed directly on the ground with little or no subflooring preparation. Flooring materials in adobe buildings have varied from earth to adobe brick, fired brick, tile, or flagstone called "lajas" , to conventional wooden floors.

Adobe surfaces are notoriously fragile and need frequent maintenance. To protect the exterior and interior surfaces of new adobe walls, surface coatings such as mud plaster, lime plaster, whitewash, and stucco have been used. Such coatings applied to the exterior of adobe construction have retarded surface deterioration by offering a renewable surface to the adobe wall.

In the past, these methods have been inexpensive and readily available to the adobe owner as a solution to periodic maintenance and visual improvement. However, recent increases in labor costs and changes in cultural and socioeconomic values have caused many adobe building owners to seek more lasting materials as alternatives to these traditional and once inexpensive surface coatings.

Traditionally, adobe surface coatings that protected the fragile adobe building fabric were renewed every few years. Women are seen here recoating an adobe wall with mud plaster mixed with straw at Chamisal, New Mexico.

Mud plaster has long been used as a surface coating. Like adobe, mud plaster is composed of clay, sand, water, and straw or grass, and therefore exhibits sympathetic properties to those of the original adobe.

The mud plaster bonds to the adobe because the two are made of the same materials. Although applying mud plaster requires little skill, it is a time-consuming and laborious process.

Once in place, the mud plaster must be smoothed. This is done by hand; sometimes deerskins, sheepskins, and small, slightly rounded stones are used to smooth the plaster to create a "polished" surface. In some areas, pink or ochre pigments are mixed into the final layer and "polished. Whitewash has been used on earthen buildings since before recorded history.

Consisting of ground gypsum rock, water, and clay, whitewash acts as a sealer, which can be either brushed on the adobe wall or applied with large pieces of coarse fabric such as burlap. Initially, whitewash was considered inexpensive and easy to apply. But its impermanence and the cost of annually renewing it has made it less popular as a surface coating in recent years.

Lime plaster, widely used in the 19th century as both an exterior and interior coating, is much harder than mud plaster. It is, however, less flexible and cracks easily. It consists of lime, sand, and water and is applied in heavy coats with trowels or brushes.

The grooves are filled with a mixture of lime mortar and small chips of stone or broken roof tiles. The wall is then covered heavily with the lime plaster. In the United States, cement stucco came into use as an adobe surface coating in the early 20th century for the revival styles of Southwest adobe architecture. Cement stucco consists of cement, sand, and water and it is applied with a trowel in from 1 to 3 coats over a wire mesh nailed to the adobe surface. This material has been very popular because it requires little maintenance when applied over fired or stabilized adobe brick, and because it can be easily painted.

It should be noted however, that the cement stucco does not create a bond with unfired or unstabilized adobe; it relies on the wire mesh and nails to hold it in place. Since nails cannot bond with the adobe, a firm surface cannot be guaranteed. Even when very long nails are used, moisture within the adobe may cause the nails and the wire to rust, thus, losing contact with the adobe. These have included items such as paints oil base, resin, or emulsion , portland cement washes, coatings of plant extracts, and even coatings of fresh animal blood mainly for adobe floors.

Some of these coatings are inexpensive and easy to apply, provide temporary surface protection, and are still available to the adobe owner.

When preservation or rehabilitation is contemplated for a historic adobe building, it is generally because the walls or roof of the building have deteriorated in some fashion—walls may be cracked, eroded, pitted, bulging, or the roof may be sagging. In planning the stabilization and repair of an adobe building, it is necessary:. General Advice: There are several principles that when followed generally result in a relatively stable and permanent adobe resource.

The following are some common signs and sources of adobe deterioration and some common solutions. It should be cautioned again, however, that adobe deterioration is often the end-product of more than one of these problems. The remedying of only one of these will not necessarily arrest deterioration if others are left untreated. There are several common structural problems in adobe buildings, and while the results of these problems are easy to see, their causes are not.

Many of these problems originate from improper design or construction, insufficient foundations, weak or inadequate materials, or the effects of external forces such as wind, water, snow, or earthquakes. Solutions may involve repairing foundations, realigning leaning and bulging walls, buttressing walls, inserting new window and door lintels, and repairing or replacing badly deteriorated roof structures.

There are many tell-tale signs of structural problems in adobe buildings, the most common being cracks in walls, foundations, and roofs. In adobe, cracks are generally quite visible, but their causes may be difficult to diagnose. Some cracking is normal, such as the short hairline cracks that are caused as the adobe shrinks and continues to dry out.

More extensive cracking, however, usually indicates serious structural problems. In any case, cracks, like all structural problems, should be examined by a professional who can make recommendations for their repair. Generally, adobe buildings deteriorate because of moisture, either excessive rainwater or ground water. Successful stabilization, restoration, and the ultimate survival of an adobe building depends upon how effectively a structure sheds water. The importance in keeping an adobe building free from excessive moisture cannot be overestimated.

Photo: NPS files. The erosive action of rainwater and the subsequent drying out of adobe roofs, parapet walls, and wall surfaces can cause furrows, cracks, deep fissures, and pitted surfaces to form. Rain saturated adobe loses its cohesive strength and sloughs off forming rounded corners and parapets.

If left unattended, rainwater damage can eventually destroy adobe walls and roofs, causing their continued deterioration and ultimate collapse. Standing rainwater that accumulates at foundation level and rain splash may cause "coving" the hollowing-out of the wall just above grade level.

Ground water water below ground level might be present because of a spring, a high water table, improper drainage, seasonal water fluctuations, excessive plant watering, or changes in grade on either side of the wall.

Ground water rises through capillary action into the wall and causes the adobe to erode, bulge, and cove. Coving is also caused by spalling during the freeze-thaw cycles.

As water rises from the ground into the wall, the bond between the clay particles in the adobe brick breaks down. In addition, dissolved minerals or salts brought up from the soil by the water can be deposited on or near the surface of the wall as the moisture evaporates. If these deposits become heavily concentrated, they too can deteriorate the adobe fabric.

As the adobe dries out, shrinkage cracks usually appear; loose sections of adobe bricks and mud plaster may crumble. A water-tight roof with proper drainage is the best protection against rainfall erosion.

Adobe wall and roof surfaces properly maintained with traditional tiles or surface coatings generally resist the destructive effects of rainwater. Roof drains should be in good repair and sufficient to carry rainwater run-off from the roof.

As Muslims migrated across northern Africa and into the Iberian Peninsula, the phrase was transformed into a Spanish word after the eighth century CE. The word entered our English language through the colonization of America by Spain after the 15th century.

The word is widely used in the southwestern United States and Spanish speaking countries. Like the building material itself, the word is ancient, going back to the creation of language—derivations of the word have been seen in ancient hieroglyphics. 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. The material is mixed and then thrown in lumps to gradually create an earthen wall, where the mixture dries in place. In the Natural Building Blog , Dr. Owen Geiger, Director of the Geiger Research Institute of Sustainable Building , contends that Indigenous groups in America used puddled adobe before the Spanish introduced adobe brick-making methods.

Adobe is resilient if well-maintained. One of the oldest known structures in the U. Preservationists at the National Park Service of the U. Department of the Interior provide guidance on historic preservation, and their Preservation of Historic Adobe Buildings Preservation Brief 5 published in August has been the gold standard for keeping this building material maintained. Constant monitoring of deterioration sources, including the breakdown of mechanical systems like leaky plumbing, is the most important part of maintaining an adobe structure.

Problems usually have more than one source, but the most common are 1 poor building, design, and engineering techniques; 2 too much rainwater, ground water, or watering of surrounding vegetation; 3 wind erosion from windblown sand; 4 plants taking root or birds and insects living within the adobe walls; and 5 previous repairs with incompatible building materials. To maintain historic and traditional adobe, its best to know traditional methods of construction so that repairs can be compatible.

For example, 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 — that is, the mortars cannot be stronger than the adobe brick, according to preservationists.

Foundations are often constructed of masonry red brick or stone. Adobe walls are load-bearing and thick, sometimes braced with buttresses. Roofs are usually wooden and laid flat, with horizontal rafters covered with other materials.

The familiar vigas projecting through the adobe walls are really the timber parts of the roof. Traditionally, the roof was used as additional living space, which is why wooden ladders are often propped up alongside an adobe home. After the railroads enabled the transport of building materials to the American Southwest, other roof types e. Adobe brick walls, once in place, are usually protected by applying a variety of substances.

Before an exterior siding is applied, some contractors may spray on insulation for added thermal protection—a dubious practice in the long term if it allows the bricks to retain moisture. Another improvement is made during walling where steel is used to reinforce the strength of the walls. The window of a classic adobe house. Benjamin Elisha Sawe April 25 in Society. Maya Civilization. Qing Dynasty.

Historical Methods Of Execution.