Green Building with Bamboo

Costa Rica Green BambooIn the world of tropical greenbuilding, bamboo is one of the most exciting and popular materials for many reasons, such as it’s strength, it’s beauty, and the fact that its a renewable resource.

The types of bamboo that you may find growing on your property in Costa Rica is probably not going to be the strongest type. There are many varieties that grow here, depending on the area you live in. For example, in Montezuma and Santa Teresa, we typically see both a yellow and green variety. The yellow one is aggressive and invasive, rapidly spreading to take over a space where it’s planted. The green on is a “clumping” bamboo that spreads out more slowly from where it starts. The green one is stronger, but neither is really ideal for building a serious structure like a house. For that, you’ll want to probably use Gadua bamboo, which is originally from the mountains in Colombia, and is the strongest variety around.

Growing your own bamboo

You may have heard that bamboo is one of the world’s fastest growing plants, so you may imagine that you can plant it and then in a few months you’ll be harvesting all the bamboo you need. Unfortunately, while individual stalks of bamboo can grow very quickly, it takes a while to establish itself. We say “The first year it sleeps. The second year it creeps, and the third year it leaps!” So basically it’s not going to do much until the third year, when you’ll see a tall stalk or two. But you can’t cut it or you won’t have any more… you need many more years before your bamboo patch is really large enough so you can take enough to build something substantial and not decimate your bamboo crop.

So, if you’re serious about bamboo, start planting now, in multiple locations, preferably with lots of sunshine and water. Along a river or quebrada is a good place. You can dig up the “hijos” (children) of bamboo and plant them like you would bananas. Or, you can cut a stalk of bamboo and if you plant it immediately, laying horizontally just under the surface, each joint will sprout a new baby. This is a great way to plant a fenceline of bamboo.

Is bamboo stronger than steel?

Fans of bamboo like to say this, and indeed, it’s true for some types of bamboo under certain types of tests. The “strength” of a material can be measured in many ways. Bamboo is very flexible, making it great for earthquakes, and an application like scaffolding. In fact, I’ve personally seen bamboo scaffolding, held together with zip ties, going up 60 floors in Hong Kong! However, it has its weaknesses too. If not treated correctly, bugs and fungus get into it quickly. Also, rain and sun break it down very quickly, and so it’s not a suitable material for long-term outside applications. But, it’s great under a roof.

What is treated bamboo?

Even the strongest bamboo will be quickly infested and eaten by termites and other bugs if it isn’t treated. There are several different treatments used in Costa Rica, but the most common, and clever method is probably to put a large tank of water, with a solution of borax (which is no more toxic than table salt) on top of a hill, with some food coloring in it. Some also add copper sulfate to the mix. The bamboo is cut and within a few hours, while it’s still partially alive, a tube is attached to the bamboo using a correctly sized rubber gasket and a pipe clamp. The solution, if it’s sufficiently high above the bamboo (around 100 feet / 30 meters) will absorb all through the bamboo. The food coloring will allow you to see that the solution has penetrated all of it at the end, and to know when to turn of the pressure.

This treatment will permanently protect the bamboo from insects, but that doesn’t mean you can put it out in the rain and sun. Bamboo is thus inappropriate for fences, which would seem a natural use. If treated, you can use it outside and it will last a few years, but it will weather quickly.

Bamboo is not hollow!

Many people who try to work with bamboo are surprised to discover that bamboo isn’t exactly hollow. It’s only hollow between the joints. So, if you have a clever idea for an invention that uses bamboo as a piping material, now you won’t be surprised when water doesn’t flow through it. If you want to use it like that, you’ll need a special drill that can bore a large hole through the joints.

Where and how to use bamboo

So where do you use it? The simple answer is that it’s best anywhere where it won’t get wet. It’s great for building a structure underneath a waterproof roof. Other uses: internal walls, lining a ceiling, furniture, rafters support structures. And of course it can be cut and carved into all types of household implements such as plates, bowl, spoons, etc.

Bamboo Splitters

You can buy a “bamboo splitter” which is basically a cylindrical ring with two handles one or more blades inside. Imagine a Mercedes-Benz symbol where the inside is three blades, and then add two handles outside. Using a mallet, you force the bamboo rod through the ring, which will split it into three equal parts. Splitters are made for splitting into two, three, four, and more equal pieces, each type of size has a different use in construction.

Do I use nails or screws with bamboo?

Most use neither. The preferred way to build with bamboo is with wooden pegs. Usually an extremely hard and durable type of local hardwood is used. Bamboo is strong, but fairly soft when you saw or drill it, so it’s fairly easy to cut a hole through it and put in a peg to join two pieces of bamboo together. Some builders also add hose-clamps to the ends of the bamboo, especially if they notice a fine split forming, to insure it’s strength.

Building with bamboo is a special art, but it’s fairly easy to learn from YouTube videos. Or you can take a class to gain more practical experience with the finer details.