Adobe

[2] Adobe bricks are rectangular prisms small enough that they can quickly air dry individually without cracking.

In dry climates, adobe structures are extremely durable, and account for some of the oldest existing buildings in the world.

Adobe buildings offer significant advantages due to their greater thermal mass, but they are known to be particularly susceptible to earthquake damage if they are not reinforced.

[5] Adobe had been in use by indigenous peoples of the Americas in the Southwestern United States, Mesoamerica, and the Andes for several thousand years.

Adobe bricks were used in Spain from the Late Bronze and Iron Ages (eighth century BCE onwards).

This was adopted into Arabic as الطوب aṭ-ṭawbu or aṭ-ṭūbu, with the definite article al- attached[9] to the root tuba.

In more modern English usage, the term adobe has come to include a style of architecture popular in the desert climates of North America, especially in New Mexico, regardless of the construction method.

[13] Another source quotes 15–25% clay and the remainder sand and coarser particles up to cobbles 50 to 250 mm (2 to 10 in), with no deleterious effect.

To withstand such loads, the codes typically call for a tensile modulus of rupture strength of at least 2.1 N/mm2 (300 lbf/in2) for the finished block.

The massive walls require a large and relatively long input of heat from the sun (radiation) and from the surrounding air (convection) before they warm through to the interior.

After the sun sets and the temperature drops, the warm wall will continue to transfer heat to the interior for several hours due to the time-lag effect.

Thus, a well-planned adobe wall of the appropriate thickness is very effective at controlling inside temperature through the wide daily fluctuations typical of desert climates, a factor which has contributed to its longevity as a building material.

Some experiments suggest that the standard consideration of conductivity is not adequate for this material, as its main thermodynamic property is inertia, and conclude that experimental tests should be performed over a longer period of time than usual – preferably with changing thermal jumps.

Straw, cement, or manure added to a standard adobe mixture can produce a stronger, more crack-resistant brick.

Heavier particles settle out first, sand above, silt above that, and very fine clay and organic matter will stay in suspension for days.

[24] During the Great Depression, designer and builder Hugh W. Comstock used cheaper materials and made a specialized adobe brick called "Bitudobe."

In 1938, he served as an adviser to the architects Franklin & Kump Associates, who built the Carmel High School, which used his Post-adobe system.

To protect the interior and exterior adobe walls, finishes such as mud plaster, whitewash or stucco can be applied.

Depending on the materials available, a roof may be assembled using wood or metal beams to create a framework to begin layering adobe bricks.

Depending on the thickness of the adobe bricks, the framework has been preformed using a steel framing and a layering of a metal fencing or wiring over the framework to allow an even load as masses of adobe are spread across the metal fencing like cob and allowed to air dry accordingly.

This method was demonstrated with an adobe blend heavily impregnated with cement to allow even drying and prevent cracking.

The more traditional flat adobe roofs are functional only in dry climates that are not exposed to snow loads.

To construct a flat adobe roof, beams of wood were laid to span the building, the ends of which were attached to the tops of the walls.