How to Join Bamboo, Basic Principles
How to join bamboo, or what are the best bamboo joints? Well first of, it is important to know a few basics principles about joining bamboo before discussing the different techniques. So here goes...
- Do not use green, fresh cut bamboo. Bamboo has to be completely dry before using it in construction (preferable air dried). During the drying process the bamboo diameter shrinks, so when bamboo is used in joinery this will result in lose and weak joints after a few weeks.
- Do not use bamboo when it is less then 3 years of age. Only use mature bamboo of 4-6 years.
- Do not use bamboo infected by insects (powder beetle for example). Bamboo has to be properly cured with a boron mix immediately after harvesting.
- Do not use bamboo that has flourished. Rest assured bamboo only flourishes once in a lifetime (60-120 years).
- Do not use bamboo poles with profound vertical cracks.
- Use appropriate cuts and joints when building with bamboo.
- Use bamboo with the right diameter and wall thickness for your project.
- Do not use conventional wood nails in bamboo joinery, they will cause the bamboo to split. Instead use nylon, steel or vegetal cord of the appropriate diameter.
- When using bamboo as a column make sure that the lower part connecting with the surface ends with a node. If not the bamboo will splinter when struck (for example to position the column).
- When connecting bamboo poles with bolts, make sure to bolt them together in between 2 nodes, otherwise the bamboo may crush. More about utilizing the nodes below...
Bamboo Has Nodes, Use Them!
In construction, using the bamboo nodes is very important. Bamboo columns or beams need to have a node at both ends (or as close as possible towards the ends), if not the pressure of a structure on the joint may crush the bamboo.
Often it isn't possible to find bamboo of the required length with both end nodes in place. When this occurs you should insert a wooden cylinder of the appropriate diameter or a fitting piece of bamboo with a node.
These are the most common cuts to use when making bamboo joints:
one ear / two ear / beveled / flute mouth / fish mouth
As you can see in the illustration below, making basic cuts in bamboo doesn't require expensive or heavy power tools, just a few traditional hand tools will work fine.
Source: Oscar Hidalgo Lopez, Manual de construccion con bambu.