Bamboo Construction in Practice

After looking at the potential, the advantages and also the limits of bamboo in the first part, we now turn to its practical use. How is bamboo processed, how is it built with, and which construction methods are particularly relevant? To start, let’s first look at some concrete examples of how bamboo can be used. A common use in regions where bamboo grows is the production of handicrafts, everyday objects, musical instruments and furniture. These include, for example, baskets, mats, bowls, tools, simple household items, or even elaborately crafted pieces of furniture.

This use has a long tradition in many regions. Woven bamboo and various mats can be used for many different purposes, including the construction of interior or exterior walls. This is a widespread, very inexpensive and simple method that works particularly well in warmer climate zones. It offers privacy as well as basic protection against the weather and against animals getting in. Another important example is scaffolding. Bamboo poles are often used for building scaffolding, especially in Asia, because they are sturdy, flexible and inexpensive.

Bamboo scaffolds provide safe working platforms, are easy to transport and can be reused many times. They are usually built from individual bamboo poles. Very well-known examples of this can be found in Hong Kong. There, bamboo scaffolds are also used on high-rise buildings and can take on very complex shapes. Another impressive example comes from Myanmar, where bamboo scaffolds are used in the construction and restoration of pagodas. The structures often look so artistic and delicate that they could almost be considered an art form in their own right. They are often more impressive than the buildings they help to erect. And after use, the scaffolds can be dismantled and used again elsewhere, just like scaffolds made of metal.

We will take a closer look later at the classic use of whole bamboo culms as load-bearing members. First, though, we turn to a more modern form of processing: bamboo laminates. Bamboo laminates are an alternative building material for elements such as downstand beams, columns, floorboards or panels. They are made from cut bamboo strips that are glued together. Depending on the manufacturing process, the bamboo species and the arrangement of the strips, different products with different properties are created.

The result is sturdy components and panels that are suitable for furniture, doors, flooring and, in some cases, load-bearing structures. In some areas, they can be a more sustainable alternative to timber. For load-bearing applications, the term Structural Engineered Bamboo, SEB, is often used. This refers to technically processed bamboo products made according to similar principles as glued-laminated timber. The manufacturing process is similar to other bamboo laminates, but is specifically designed for high strength, high density and high load-bearing capacity. Bamboo can also be used in combination with concrete, for example as a replacement for steel reinforcement or in the form of bamboo shavings as an aggregate. Both approaches have already been tested in individual projects and studies. Even so, great caution is necessary here. The application is still hardly standardized and should therefore above all be understood as experimental.

Let’s briefly look at the steps that are needed before bamboo can be used as a building material. Most bamboo species prefer warm regions with high humidity of over 80%. They mostly grow in loamy, moist soils and are often found near water sources. Bamboo grows extremely fast, often several centimeters a day. New culms reach their full height in three to six months. Unlike trees, bamboo culms emerge from the ground with their final diameter and do not get thicker later on. After that, they harden over three to six years, during which the moisture content drops from up to 80% to about 20%. If the culm is not harvested, it dies after about seven to ten years.

Bamboo is usually cut with a machete or a saw directly above the first or second node. A slanted cut helps to prevent water from collecting on the cut surface and thus reduces the risk of rot. Bamboo is best cut in the dry season and outside the main growth phase, because the culms then contain less moisture and the sugar content is lower, which makes them less susceptible to pests.

For use in construction, bamboo must be selected carefully, because the quality of the individual culms has a great influence on stability and durability. Mature culms that are about three to five years old are best suited. Younger ones are often still too soft, while older ones can lose strength. Straight-grown, thick-walled culms with a diameter that is as uniform as possible are especially suitable. They should have no cracks, no traces of insects or fungi, and no other damage.

A dense, hard fiber structure is also important, especially if the bamboo is used as a load-bearing material. After cutting, the bamboo culms should first be dried to reduce moisture and sugary starch, which attracts pests. There are various methods for this. The most common and cheapest option is to dry the bamboo naturally on site. For this, the culms are stood upright and leaned against each other or against another surface, at first still with their branches and leaves. They stay in this position for at least four weeks, drying through evaporation via the leaves. After that, the branches and leaves are removed and the culm continues to dry in a covered, well-ventilated place.

Bamboo must be well protected because it is susceptible to insects, fungi and other organisms. Since the culm walls are fairly thin, even minor damage can significantly reduce load-bearing capacity. There are various traditional and modern protection methods, for example smoking, heat treatment, lime protection or storing in earth. Most commonly, bamboo is treated chemically by soaking the culms in a boron-based solution of borax and boric acid. This method is considered a kind of best-buy solution. It is comparatively inexpensive, technically simple, widespread, low in toxicity and very effective. Even so, bamboo must still be well protected from rain afterwards.

The treatment usually takes one to two weeks, while the culms lie completely in the solution. After the treatment comes a second drying phase. It lasts a few weeks, and direct sunlight should be avoided if possible. Overall, the process is technically fairly simple, but, as you can see, it takes some time and careful execution. After installation, like timber, bamboo can be treated with standard commercial coatings to better protect it from UV radiation. Moisture is one of the greatest dangers for bamboo. If it is stored wet or lies directly on damp ground, it can become moldy, rot and lose strength. So bamboo should be stored dry, well ventilated and, if possible, raised off the ground. After heavy rain, it should be checked and excess water should be removed. Strong sun can also cause damage, because it dries out the bamboo and causes cracks.

At first glance, building with bamboo looks similar to building with timber. But there are big differences. Some of them are advantages. Bamboo is very light and has a high tensile strength comparable to steel. This makes bamboo construction particularly well suited to earthquake-resistant structures. At the same time, we must not forget that bamboo is basically a giant grass. The culms are hollow and have fibers mainly in the longitudinal direction. For this reason, bamboo cannot simply be joined like timber.

Nails or screws cannot be used directly, because the culms would otherwise split quickly. This makes joining the individual components much more difficult and turns the connection points into potential weak spots. These joints have developed further over time. In the past, natural fibers, leather and wooden dowels were often used. Today, synthetic fibers or galvanized wire are also used. What is always important is that the forces are transferred well. For this, the components should lie against each other over their full surface where possible. A particularly common cut for such joints is called a fish mouth and looks like this.

Joints can additionally be reinforced with mortar in the cavities, to allow better force transfer and to prevent crushing and splitting. These examples show: joints are one of the most complex topics when bamboo is used. Bamboo culms are particularly well suited as columns up to six meters in height or as arches, but less so as beams, since their span is limited to about two to three meters. That is why beam trusses are always used when greater spans become necessary. There are many examples of large bamboo trusses that are used for bridges or long-span buildings.

Special bamboo systems are often used here, rather than simply rectangular trusses. The challenge lies in the joints, which must be stiff enough so that the entire element does not deform. Because of these various weak points, durability through design is an important part of building with bamboo. As with earthen construction, bamboo structures should stay as dry as possible so that they do not rot. Large roof overhangs protect against rain. In addition, bamboo must never touch the ground directly and should be installed slightly raised to better protect it from splashing water or flooding.

That is why foundations and the plinth area are usually made of concrete or stone. At the same time, bamboo must not rest directly on the foundation, since moisture can otherwise penetrate through capillary action. That is why bamboo and foundation are separated by a steel rod or a similar connecting element, or moisture barriers or special coatings are used. Also worth mentioning are more advanced systems such as Composite Bamboo Shear Walls, or CBSW for short.

Here, whole bamboo culms are combined with special joining techniques and a protective exterior plaster. The system resembles traditional wattle-and-daub construction such as Bahareque in Latin America. There it is also called Cemented Bahareque. The structure consists of a load-bearing frame made of bamboo and timber. This is enclosed with a woven lattice, for example of flattened bamboo strips, and usually finished with a cement mortar plaster. This creates wall panels that can be used as load-bearing elements for the walls of the house.

The distances between the walls depend on the floor or roof construction, which usually also consists of bamboo elements. As a rule, they are at most three to four meters. This system is particularly suitable for low residential buildings with one to two stories, especially in regions where a lot of bamboo is available. From a sustainability perspective, it is of course a compromise, because cement is used. However, various studies show that these houses have an overall carbon footprint about 50% lower. The system can also be implemented so that it is earthquake- and cyclone-resistant. The cement plaster additionally provides a fire resistance of 30 minutes. A good source on this building system is a manual produced in collaboration between INBAR and Base Philippines. It shows the entire process step by step in a simple and understandable way.

Today’s use of bamboo in building projects can be roughly divided into three categories. As already mentioned, the simplest way of building with bamboo resembles traditional timber construction. Basically, it is a simple frame construction. Vertical bamboo posts carry the weight, horizontal elements connect the construction. Ideally, cross braces are added as well, which stabilize the whole structure. The roof structure is usually built with beam trusses. There are many examples of such simpler bamboo constructions with very different levels of complexity and very different finishing standards. The CBSW systems already mentioned are somewhat more complex, but can be understood as a further development of this simple principle.

Here we see examples of this approach from three companies that focus mainly on bamboo construction. All three also have a strong social component. Their work shows that bamboo is not only a practical building material, but can also be a tool for social empowerment. The first example comes from Myanmar and is by the social enterprise Housing NOW. The organization’s projects and approaches are shown in more detail in a separate video on this platform. Here we see a housing project near Mandalay.

It was carried out as earthquake relief and supported families in rebuilding their homes. The houses were built relatively simply by the local people themselves. Housing NOW supported them with material sourcing, financing and technical knowledge. The materials used depended on the location and on local availability. These photos show a combination of timber and bamboo for the load-bearing structure. Timber was mostly used for components exposed to rain, bamboo where it was better protected.

Another project goes one step further. It is basically a simple manual that is shared in communities. The aim is to help people build more durable bamboo structures themselves. The guide explains in a simple way how bamboo can be better planted, cut and treated. It also contains a simple plan for a small house as well as basic advice on technical questions such as wall protection, joints and connections. Almost like an IKEA instruction sheet.

The second example comes from Guatemala and is by the construction company Cassa. Cassa is a commercial company that mainly builds residential buildings. Many of these projects include various components made of bamboo. One of their projects is a pilot project for a small family house of about 70 square meters. It was built with the support of the Climate Smart Forest Economy Program. The entire process was well documented and all the content is now freely accessible and can be used and adapted by anyone interested. This includes plans, budgets, videos and many photos of the building process. A very useful reference.

The two-story house is intended to offer a durable and climate-resilient housing solution and is built almost entirely from bamboo. As in other examples, it is raised on concrete columns to better protect it from flooding. It is designed so that it can be built with a few simple tools and simple techniques that are accessible to people anywhere in the world. The building standard and quality are relatively high. At the same time, the load-bearing components are very simple and logical in design.

Apart from the foundations and plinth area, almost everything consists of bamboo culms: columns, walls, floors and even a very simple roof that manages entirely without beam trusses. Some of these structural solutions and details work mainly because of the relatively small floor area of five by seven meters and the high-quality, very thick Guadua bamboo available in Guatemala. In other countries and under other conditions, such solutions would of course have to be adapted to local conditions and to the bamboo species available there.

The last example comes from the Philippines and from Kawayan Collective, another social enterprise. It focuses mainly on the production and treatment of bamboo and sells ready-made modular panels and other bamboo products. They want to make bamboo building better known and improve the image of the material. To do so, they work with local farmers, offer training and are involved in various social projects and initiatives. involved.

One of these projects was developed in collaboration with Base Philippines. A house with Cement Bamboo Frame Technology. This is basically another name for the CBSW walls already mentioned. Prefabricated modular panels are made from bamboo culms. A flattened bamboo mat is attached to one side. After the panels are installed, cement mortar is applied. It protects the exterior and stabilizes the structure. As with the project in Guatemala, the entire building process here is also very well documented. With videos on YouTube and information on their website explaining the construction step by step.

At the same time, this is a completely different level of building standard and craftsmanship quality. It leans more towards commercial resort architecture. All of this takes place in the Philippines, where there is a long tradition of working with bamboo and high-quality bamboo is available in large quantities. For development cooperation, certainly not everything at this level can be transferred directly. At its core, however, it is a simple system that can also be adapted and implemented in other situations and in other places.

If we move a bit further to neighboring Indonesia, we reach an even higher level of bamboo construction. There, bamboo is used for very complex and demanding designs. Here we show some examples from one of the best-known architecture firms in the field of bamboo architecture, the Bali-based firm IBUKU. Projects like the Green School in Bali show how bamboo can also be used for large and innovative buildings.

Typical are complex structures, for example hyperbolic paraboloids or vaulted roof shells. These forms enable high stability and use the material very efficiently. The constructions take up the natural flexibility of bamboo and combine traditional joining techniques with modern engineering methods. This kind of organic architecture cannot simply be transferred. Nor should it serve as a model for the projects that are the main focus here. Still, it is important because it shows the potential bamboo can have as a building material when used by experts.

Such images quickly give the impression that almost anything is possible with bamboo. At the same time, it is important to put this impression into some perspective. Online, such spectacular examples are often in the foreground. They are impressive, but show only one side of bamboo construction and can make it seem very complicated. As we have seen in the other examples, it can also be much simpler. With bamboo, as with many alternative methods, the most realistic approach is often a combination with other materials.

What makes sense depends on the context. Availability, cost, climate, existing know-how and other factors. In this way, the strengths of different materials can be used and weaknesses offset. This can also happen very simply and low-tech. What matters here: foundations and plinth areas almost always consist of concrete or stone. But that doesn’t really count as a hybrid here, rather as a necessary basis. You can also see this in Housing NOW’s projects.

In some clinic projects, the main load-bearing structure is made of timber, while bamboo is used for secondary components such as rafters or beam trusses. In other projects it is exactly the other way around. The main structure is made of bamboo, while individual secondary elements are built from timber. So what matters is not to use one material consistently everywhere, but to find the right solution depending on the component and situation.

Another example comes from a project in Ecuador. There, the main outer structure was first built with Superadobe on a stone foundation. A separate bamboo system with columns and a roof was then inserted into it. This protects the bamboo better from rain. Another example shows Bahareque walls combined with a structure made of bamboo, either for exterior or interior walls. Throughout this video you can see again and again: other materials in bamboo construction are often used mainly to protect the bamboo.

This applies to timber, concrete, cement, or even Bahareque walls. Most of the time the aim is to protect bamboo from rain and moisture, because that is one of its greatest weaknesses. To be completely safe, bamboo can be used only indoors, where it is fully protected. If it is used outdoors, it needs additional protection, for example water-repellent coatings of linseed oil or latex paint. These must be renewed regularly, though. For high-quality buildings or bridges this can make sense. For simple houses it is often less realistic.

How long does a bamboo structure actually last? Surprisingly few clear answers exist to this question. According to the European standard EN 350, untreated bamboo falls into durability class five. That means not durable, with an expected service life of five years at most. This puts untreated bamboo on a par with the most vulnerable wood species. And because bamboo culms are usually relatively thin-walled, even little decay can quickly reduce the load-bearing capacity.

Of course, bamboo used in construction today is almost always treated. If the culms are also well selected, properly harvested, installed under protection and well ventilated, then according to various expert sources a service life of around 50 years is entirely plausible. The most important word here is “protected”. In this case, load-bearing bamboo members in particular are not directly exposed to the weather. It gets more complicated with structures made of whole bamboo culms located outdoors. This is especially critical for bridges or for more elaborate structures in which many bamboo elements are at least partly exposed.

Even high-quality, well-treated bamboo ages over time, even if it sits under a large roof overhang and is protected from UV radiation and rain by coatings. Usually the parts closer to the plinth are less well covered and are therefore damaged more quickly. First, sun and weather bleach the outer surface and damage it. The constant alternation of sun and rain then leads to cracks. Once moisture penetrates through these cracks, rot and fungal attack are usually not far behind. Various studies show: outdoors, bamboo almost always develops cracks over time.

This raises the question: what can be done about it? The most important thing is a regular inspection of the outer surface. How often it is needed is hard to say. Exposed members of course need to be checked more often. First cracks can appear after just three months, even on varnished culms. That is why special attention is particularly important at the beginning. As soon as cracks become visible, they should be closed with sealants or with a mixture of sawdust and glue, so that no moisture can get in. Coatings on exposed members must also be renewed regularly, at the latest when the protection visibly weakens.

Another aim of the inspection is to detect rot or pest infestation early. For this, all bamboo members are checked visually. Important signs are possible discoloration, small holes, or feeding tunnels made by beetles and termites. Since rot often develops in concealed and poorly ventilated areas, tapping the bamboo culms can also help. The sound can give hints as to whether the culm is still in good condition. Of course, all other parts of the building must also be kept in good condition.

Roofs and gutters should be repaired immediately so that no water gets in or splashes onto bamboo members. Walls that protect the interior should also be checked regularly for cracks, especially in CBSW systems. The ISO standard also describes another approach: planning for later replacement. This is not directly about durability itself. Instead, the design should already take into account that individual bamboo culms will be damaged later and have to be replaced. To do this, the structure should be designed to be redundant.

This means there are several load-bearing elements, and the structure is calculated so that not everything fails immediately if a single element is damaged. According to the standard, a member or structure can be considered redundant if there are at least four load-bearing elements and it has been calculated accordingly. Each element should then be designed so that it can lose 25% of its load-bearing capacity. An example would be a column made of four bamboo culms. If a single culm is damaged, it could be removed and replaced under controlled conditions, without the entire structure collapsing.

Overall, there is so far no research that shows exactly how long structures with partly exposed bamboo actually last. IBUKU states a minimum service life of 25 years for its own buildings. Various sources consider 50 years realistic if the structures are designed and built to a high standard and regularly maintained. At some point it also always becomes a question of budget, similar to buildings made of conventional materials. Repair is always possible. The only question is: is it worth it?

The existing documentation speaks much more confidently about the potential of bamboo than about a proven 50 years of service life. Most of the well-known and well-documented examples are not yet 25 years old. On the other hand, for older projects, easily accessible information is often lacking about what condition they are in today and how maintenance has worked over the years. Even if this information existed, service life depends on a great many factors: on the bamboo species used, on the design, on the climate, and of course on the maintenance we just talked about.

What works with high-quality Guadua bamboo in Colombia can look quite different in, for example, Ethiopia. One thing is clear, though: if long-lasting structures are the goal, the safest solution is to use bamboo where it is fully protected by the outer building envelope, for example in roof structures inside CBSW walls or in the interior. And if a service life of 15 years or more is not the most important requirement, which is more often the case than you might think, bamboo becomes a very suitable material. Then many of the risks mentioned earlier matter less.

To conclude, let’s take a brief look once more at how Housing NOW implemented this in Myanmar in practice. Myanmar, also known as Burma today, is going through historical political events. Since February 2021, more than 400,000 people have been internally displaced in the country. We started this project in Mingaladon, in the industrial zone of Yangon, Myanmar’s major city. In order to guarantee the structural performance and safety of the structure, we have been building prototypes over and over, testing each connection and improving the design little by little.

Very small bamboo represents an untapped and abundant resource on the local market. They are never used in construction because they are too small. But if you bundle groups of bamboo together, it can become even more resilient to damage compared to more conventional construction methods. Blue Temple is an architecture design studio based in Yangon since 2017. We have been focusing ever since on the construction of community space in Yangon. These projects have been transformative, regenerating urban leftover spaces, creating public space, playgrounds, and more. Bamboo has been our main source of inspiration as an affordable and traditional construction material.