Why Bamboo Architecture?

Any kind of architecture and construction needs two types of materials: one that can take pressure/load and one that absorbs tension. That is why the combination of concrete and steel has become so successful: concrete as load bearer and steel to buffer the tension and shear forces. This is where bamboo architecture comes into play.

Here are some facts to show you that bamboo is not just a material for green eco freaks but a seriously competitive construction material with far reaching implications:

  • The tensile strength of Bamboo is at least the same as steel (40kp/mm2), some research says even superior to steel. The strong tensile fibers are in the so called skin of the bamboo, which also has a high content of silica and protects the inner “meat” against the elements and insects.
  • The inner part or “wood” has a similar hardness to oak wood and thus has a good load bearing capacity as well
  • Its structure is like a tube, reinforced by segments. This results in a lighter weight and at the same time this profile protects much better against bending and breaking than the rod profile of a steel rod
  • Unlike steel it is not a heat conductor but a great insulator which means roofs made of bamboo automatically create a cool interior
  • Because of its great feel and good looks it creates a warm room feeling without much effort
  • Good for the planet: it needs little energy to grow, produces more oxygen than other plants and binds more CO2. Therefore bamboo construction reduces the carbon footprint enormously and easily qualifies for carbon credits

What is Bamboo?

Bamboo or Bambusoideae belongs to the family of Graminae or grasses, like rice, corn, etc but it is the largest.
There are many genera in the Bamboo family such as bambusa, fargesia, dendrocalamus, phyllostachys, and each genus covers many species: altogether there are over 1600 species in this world. 64% of these are native to SE Asia!

Only a few are useful for bamboo architecture construction though, and every country has its own good ones. The biggest and strongest bamboo in Thailand is dendrocalamus asper.

Bamboo as Construction Material:

In its first years bamboo is full of starch which is why the panda bear, elephants, human and insects like to eat it. Over the years the sugar content decreases and the fiber content increases. So in its early years the bamboo is food but becomes construction material later on after about 4 years. therefore the right choice of bamboo is paramount to quality construction. This is where most builders go wrong. After the right selection the bamboo should be treated further. We use Borax salt and boric acid. They are preservatives, repel insects, act against mold and are fire retardants as well.

For further information on bamboo treatment click here

Economic facts on planting Bamboo:

  • Bamboo grows very fast: 1.2m/day or 1mm/minute; which means you can watch it grow.
  • The result of this phenomenal growth rate is that after planting a bamboo plant, the first harvest can be taken in 3-5 years unlike wood where the first harvest is at least 25 years down the road.
  • We said “first harvest”, because the bamboo has a root system called Rhizome, which grows laterally and produces new bamboo shoots every year. So if the harvest is done correctly, nothing new has to be re-planted and at least 10% of every plant can be harvested per year without any further investment. Again unlike wood – once you cut the tree that’s it.
  • Because of these characteristics, one bamboo plant produces about 10,000 m of bamboo material in 20 years
  • This easily qualifies Bamboo for the highest biomass/time: at least 12x of normal wood!

The Bigger Picture for Policymakers:

  • Lower transportation and fuel costs as bamboo can be planted anywhere and doesn’t need to be transported like steel from steel plants to distribution centres. That means less fuel imports etc
  • Because of its local nature, bamboo prices are under national control. The price of any material that has to be transported like steel is closely connected to international market situations. Oil problems, strikes etc will increase the price without local control.
  • Government budgets supported by using more locally available or produced materials instead of imported ones
  • Produces local employment at plantations, treatment and processing centers and therefore keeps a lot of the production money in the country
  • Control of the supply chain
  • Independence of international economic problems such as:
    • increase in oil prices,
    • labour strikes and
    • disruptions of supply chains by natural disasters

resulting in:

  • Raw material shortages
  • Price increases of imported products

Some general rules for bamboo architecture and construction:

  • First and most important: chose the right age and species for the right task. Young bamboo contains too much starch, proteins and water and not enough fibers. It is not only a delicacy for most insects, it is also structurally not so competent and will crack inevitably when drying
  • If you want your structure to last more than 2 to 3 years only use treated bamboo! The best documented and at the same time non-toxic way to treat is using borax salts and boric acid. (see our Bamboo Treatment page).
  • Design in a way that your bamboo is not exposed to water. Bamboo doesn’t like moisture – it will crack if exposed to repeated dry/wet cycles
  • Again design in a way that the bamboo is not exposed to the sun. Bamboo doesn’t like strong sunlight – it will crack
  • Design triangles for stronger buildings
  • Use creative connections:
    • never use nails,
    • screws are good but bamboo dowels are the best;
    • nuts and bolts for heavier loads,
    • pre-drill
    • rebar for tension, concrete for compression

 

Sources:
http://www.networkearth.org
http://www.bamboocentral.org
http://www.bamboofencer.com

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