While bamboo poles are a popular material for things like furniture and decorations, especially for outdoors, it is also strong enough to build houses. This feature is relatively unknown in North America and Europe, because most construction-grade timber bamboos grow mostly in tropical parts of the world.
Not only is bamboo actually stronger than more conventional timber, it also grows several times faster, making it more sustainable and kinder to the environment.
Measuring the strength of bamboo
The International Organization for Standardization drew up ISO 22157 in 2004 to describe how bamboo poles should be tested for:
- Bending strength - Using the four-point bending test, the bending strength of most species is between 50 and 150 Newtons per millimeter. Bending strength is an important contributor to the way a structure is going to behave.
- Compression - Because bamboo poles do not have a uniform cross-section along the entire length, measurements have to be taken from the bottom, middle and top of the pole. There are two kinds of compression strength: parallel to the grain and perpendicular.
- The compressive strength of bamboo is roughly between 40 and 80 Newtons per square millimeter, which is two to four times the strength of most types of conventional timber. Strength varies with the age and moisture content of the material, and bamboo with a lower moisture content will have a higher compressive strength.
- Tension - The tensile strength of a sample of bamboo is determined by measuring fibers, and not the poles. By testing samples of a wide variety of bamboo species, experts have determined that it has a tensile strength of 160 newtons per millimeter, or three times higher than many traditional types of timber, and is even comparable to steel.
- Shear - When using bamboo in construction, maximum shear stress is important for when it comes to designing connections and joinery systems. Parallel to the grain, the average shear stress of bamboo is between 10 and 20 times lower than the compressive strength of the same species, although this is still twice the strength of ordinary timber.
Advantages of bamboo in construction
Bamboo is one of the fastest-growing plants on the planet; some species can grow 35 inches in 24 hours. Compare this to redwood trees in California, some of which were alive in biblical times. For the purposes of erecting scaffolding or building homes and bridges, it is clear which is more economical and better for the environment.