Masonry oven India, tandoors are traditional clay ovens, although these days modern electrically fired tandoors are available. The open-topped tandoor is a transitional design between the earth oven and the Roman-plan masonry oven. In the precolumbian Americas, similar ovens were often made of clay or adobe and are now referred to by the Spanish term "horno" (meaning "oven"). Horns are also traditional in the American Southwest. The traditional direct-fired masonry design is often called a "Roman" or "black" oven and dates in Western culture to at least the Roman Republic. It is known as a black oven because the fire generates soot
Earth structure principal directions, based on wall thickness, story height, bracing wall spacing, and the roof, loft and second story weight above earthen walls. Building techniques that are more ductile than brittle, like the contained earth type of earthbag, or tire walls of earthships, may better avoid collapse than brittle unreinforced earth. Contained gravel base courses may add base isolation potential. Wall containment can be added to techniques like adobe to resist loss of material that leads to collapse. Confined masonry is effective for adobe against quake forces of 0.3 g may be useful with earthen masonry. Many types of reinforcement can