Many natural building techniques are inspired by vernacular architecture from around the world -- artisanal techniques that are used to create unique structures, which demonstrate the evidence of human touch.
The re-examination of these traditional techniques in the context of building science and engineering has delivered a way of building that fits with today's ecologically mindful lifestyle, complies with codes, and withstands the test of time. Natural buildings are healthier for the people who live in them and healthier for the planet.
Overview
Bamboo has been used in construction for thousands of years. It is estimated that there are over 1200 species of bamboo in the world. The poles can be used in building construction, furniture and other artisanal and craft purposes, or the material can be process into laminated boards, beams and sheet goods. Bamboo poles can be lashed together with cord or rope, joined using traditional pegs and dowels, or - as in modern structures – connected using bolts and cement mortars to attain engineered construction parameters.Structural
The combination of its cylindrical shape, high silica content and the orientation of the vascular tissue is unique when compared to lumber, earth, concrete or steel. The vascular tissue grows in bundles of delivery tubes that are in line with the growth of the pole except at the occurrence of nodes and branches, where a complex diaphragm is formed inside the otherwise-hollow plant.* Testing has shown certain species of bamboo to have up to double the compressive strength of concrete & tensile strength comparable to steel. Consider bamboo’s weight-to-strength ratios and the minimal processing needed to capitalize on this strength, this giant grass is an ideal natural building material.
*Bamboo is relatively easy to cultivate. Many species grow in slightly acid soils with few nutrients. There are over a thousand species that grow in diverse climates from the hot tropics to snowy temperate regions.
Climates
With so many species and variations, bamboo can be found in tropical, sub-tropical and temperate climates alike. In each zone different species will have found traditional applications appropriate to climatic and environmental conditions.Limitations
Bamboo has a few limitations that must be designed for. Its high sugar content makes the plant susceptible to rot and pests. This can be mitigated through material-specific building design and proper post-harvest treatment processes. Though individual poles have a great amount of strength, great care must be taken in detailing connections to properly transfer loads. Numerous traditional and modern techniques exist to aid in the design process. Individual poles can strain or fail unnecessarily without appropriate design and proper connections.
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While straw has many uses, in industrial agriculture it is generally considered a waste product. Straw is the stem of cereal crops, which is left over after the harvest and often tilled under, or in the case of much rice-straw in California, burned.
Straw bales have been used to build houses since the invention of the baler in the late 1800s. Some houses of that era are still standing today. Straw bales have a very high R-value (estimated values of straw bales range from 1.5 to 2 per inch), which means that straw walls insulate much better than conventionally built walls.
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There is reason to be concerned about the use of adobe in seismic zones. However, a few guidelines result in quake-safe buildings. Even in California, seismic zone 4, there are adobe buildings from the 1800's that are still standing. Aid organizations around the world have been working to improve the durability and resilience of adobe building.
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Lime plaster (lime putty mixed with sand and sometimes a natural fiber) is an ancient plaster popular for its durability and its natural ability to deter fungus and bacteria.
We produce our own lime plaster as well as apply products from several distributors including Natural Hydraulic Lime, a fast setting plaster appropriate for exterior and interior use.
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Lime wash is a traditional paint that has been used for thousands of years. As with lime plaster, lime wash is made from limestone, which is found all over the world. Often called "white wash" because of its natural bright white color, lime wash can be used to create a multitude of different colors when mixed with earth pigments. Lime wash is best suited for exterior use and works especially well over cement stucco and lime plasters.
Building with cob can be time consuming, however the use of machinery (like tractors) or hosting work parties can speed up the process.