fired brick, or ceramic tile. When finished with mud straw plaster, a thin layer of clay earth and straw is baked on to the structure at the end phase of firing, and a second layer of the plaster troweled on after cooling. When finished with tiles, they are mortared directly over a waterproofing layer such as tar. Forms and techniques The primary shapes of a ceramic building, are squares and rectangles with roofs that are arches, vaults, and domes. This is in order to construct the entire structure of monolithic material (cost effectiveness) and also to achieve the tremor resistance and proven longevity of a shell membrane. Adobe and clay can be sculpted into built-in forms and structures, such as seats and shelving, and fired with the rest of the house. Adding oxides and different types of sand and clay can create different finishes. The most important mineral oxide in glazing is silica (which makes glass). Low fired glazes are preferable for houses. Glazing should only be done in some places to allow for a room's skin to "breathe." Glazes have even been made with recycled glass bottles. Salt glazing is another way to make an inexpensive finish. Benefits There are many potential benefits to firing an earthen house. Firing makes a clay structure water resistant. Ceramic kilns often outlive the earth constructed buildings they are close to. The materials for this type of building are accessible to those with very basic resources. Fuel for firing is the most expensive investment. The hardened membrane of a ceramic dome improves resistance to earthquakes. The structure of a ceramic house improves passive heat use through thermal mass. Added benefits involving the firing process include the opportunity to produce other ceramic goods for use or income, and, when firing an existing house, pest evacuation will occur naturally. Examples Experimental fired earth housing has also been constructed using the principles of an ancient Chinese anagama kiln. In the anagama kiln system, a wood fire is built at the base of a slope, and the gases are drawn by a strong draft up the slope through a tunnel. When a dome is constructed at the end of the tunnel out of clay, the hot gases bake the clay structure to ceramic hardness. See also Earthbag construction Adobe Appropriate Technology Mudbrick Rammed Earth Anagama kiln References External links Archnet Cal Earth 'Flintstones' House Made Entirely of