Alternative Construction (continued - p2 of 2)

Cob Home Construction

Cob homes are built similar to adobes. Like the bricks used for adobes and ceramic dome homes, cob is made of sand, clay and straw, but the straw isn't usually sifted. Cob is formed into walls that are allowed to dry as they are built, rather than using bricks that have already been formed and dried. As with nearly all earthen homes, cob buildings can be built with stone or grancrete footers and foundations, wood frame, steel frame, domed or arched roofs (with or without frames).

Straw Bale Building

Like stone, clay, soil and most other earthen building materials, straw bales provide a good deal of insulation for helping to regulate temperatures and reduce energy costs. Straw bale construction is done by stacking straw bales on top of one another over a raised footing or foundation to form walls. Straw bales are tied together with pins, stakes, wood, rebar or wire mesh, then plaster and stucco is applied inside and out. Straw bale buildings are often built with wood framed roofs and wood framed walls for extra load bearing support, though it is not always necessary.

Rammed Earth

Rammed earth buildings use wood frames for walls and roofs as stick built homes do but in this case, soil (sand, gravel and clay) is moistened with water and compressed within the walls, then the wood frames are removed and the walls are allowed to dry and harden for several days or more. Footers and foundations can be made of stone and/or grancrete, as with nearly if not all forms of green architecture. Rammed earth buildings can take up to two years to completely dry and harden, but the longer they cure the stronger they are.

Earthship Homes

Earthships are made with tires (usually used tires that would otherwise go to the dump or a landfill), are typically built in the shape of a U, and are mostly or completely underground. Tires are filled with rammed earth and serve as exterior walls, while interior walls are often made from recycled cans and bottles that are held together with concrete or grancrete. The building itself is usually positioned so that the open end of the U shape faces south for passive solar design and general temperature regulation purposes.

Container Architecture

Buildings can also be made using steel frames, culverts, train cars, shipping or cargo containers and other structurally sound steel frames or containers for the actual load bearing structure. Wire mesh is attached to the steel frame or structure and fillers such as adobe, cob or grancrete are used to cover and fill in the gaps, to cover walls, ceilings and floors. Interior walls are then plastered and exterior walls are covered with stucco.

Natural Plasters, Stuccos and Mortars

Walls, ceilings and floors are often covered with natural plaster or stucco for extra water and fire proofing, and even for aesthetic purposes. Plasters are used on the inside, stuccos are used on the outside and mortar is placed between bricks to hold them together. Mortar is usually made from the same building materials as the rest of the structure, while plasters and stuccos are usually made with sand, sifted straw (or wool, cattail or other fibers) and cement (or grancrete, lime or gypsum); small gravel is also sometimes included. Sand and crushed stone may be added to concrete or grancrete as filler and for additional strength, while rice flour and/or ground oyster shells may be added to clay building materials, mortar, plaster and/or stucco for added strength and water proofing.