An Architect’s Guide to Building With Bamboo

The permaculture movement is growing around the planet, as individuals look to lifestyle alternatives and the possibility of living off the grid in a sustainable and self-sufficient way. From organic farming to building passive houses, this movement has inspired the sharing of knowledge and the adoption of new materials as solutions to reducing one’s individual carbon footprint and to removing oneself from the stress of our high-speed and technology-heavy daily lives.

One material that has resonated as a reliable and sustainable material for the future of construction is bamboo. Alejandro Chellet is a permaculture expert who has held and been part of many building workshops in Mexico, Brazil, Colombia and the US, among many other countries. Over the course of these workshops, he has experimented with bamboo constructions and installations that not only stretch the creative boundaries of bamboo-building but also bring the material into a public spotlight as a key material for future innovation.

First and foremost, bamboo has the ability to grow fast and with little maintenance. A bamboo forest can stem from one shoot of bamboo. Once it is planted in the soil — horizontally and below the ground — the shoot will begin growing roots from the nodes, bringing humidity into its ecosystem to produce new life.

Bamboo can grow all around the world, and while it grows best in areas closest to the equator, we see it being harvested in various other areas of the world, as it continues to adapt to shifts in climatic environments over continents. This diversity in growth environments naturally leads to the cultivation of very different strands of bamboos. The multitude of characteristics that bamboo can attain from growing in Southeast Asia, South and even North America, results in the obtention of a drastically volatile material, which is impossible to classify in the words and functions of a civil building code, unlike traditional timber materials.

“When one plants a bamboo, the first shooting that comes out is often weak,” explains Joana Torres, an architect who has worked extensively with the plant. “The next shooting is stronger, and the next one is even stronger, and so on.” Once the bamboo has been cut down and allowed to grow two or three times, it becomes construction-grade material. It is best to harvest bamboo that is between four and six years old, as it is too flexible before that threshold is reached and starts to weaken again after it reaches its eight-year benchmark.

Bamboo is a solid material, often referred to as a fit alternative for steel, but it is also quite fragile, as it is made of fiber and can succumb to cracking along its core. Moreover, as a living material, it requires treatment and protection from natural circumstances such as humidity, wetness as well as heat and sunlight.

All nutrients for the bamboo travel through the fiber, heavily saturating the plant with sugar that attracts microorganisms and can lead to rotting if it is not harvested properly. Like tides, the prime time for bamboo harvest depends on the cycles of the moon. Before the full moon, the higher parts of the stem and the leaves of the bamboo are full of sugar-saturated water; however, once the full moon has passed, the water will be pulled down with gravity, taking the starch concentration out of the plant and into the grounds.

The bamboo is not uprooted from the ground but rather cut close to its base, above the second visible node. Traditional harvesting methods observe a natural drying process, wherein the bamboo trunk is placed to dry in the forest for about a month, on a non-water-conducive base like a rock. Nowadays, it is often treated with solutions like borax, which is absorbed naturally by the bamboo through an immersion or insertion process so as to protect it from invasive microorganisms.

The bottom part of the bamboo — where the diameter of the stem is larger and nodes are closer together — is stronger and tends to be used for heavy construction, scaffolding, civil works construction and so on. The top part, on the other hand, can be used for accessorial parts — ceilings, for example — as it is lighter and less sturdy.

Overall, bamboo is an incredibly lightweight material that can be used to accomplish stable, weight-bearing structures, a quality that the construction industry cannot overlook. Available at a low cost in areas where it grows, it is also an easy and affordable material to transport, once again thanks to its low weight.

The challenge of normalizing the use of bamboo across the construction industry principally stems from the structural and mechanical variations that result from a material that encompasses over 1,200 species and evolves uniquely with age and moisture content.

While all mainstream construction materials are held to standards that help engineers calculate structural balance in buildings, bamboo is unable to be standardized in such a way. However, standards have been made locally, such as in Colombia where rural construction workers collaborated with the government to determine a code that brings together the locally grown material with their modes and techniques of construction.

Source: https://architizer.com/blog/practice/details/how-to-bamboo/