The criteria to assess bamboo structures cannot be the same as those for timber, masonry or modern buildings.
The writer is an architect working for eco-friendly designs and can be contacted at firstname.lastname@example.org
Often we get to see a many-decades-old tiled house being replaced by a new RCC-roofed house. The chances that the old house roof was supported by bamboo rafters is very high. Repeatedly coated with cashewnut oil in coastal areas, hence surface protected, these rafters would have hidden their actual age. The north-eastern States virtually live with bamboo – pile foundation, support pillars, floor sections, wall mats, roof supports, window frames, objects to live with and such others. Despite all this, we feel bamboo is a mere local temporary material.
Possibly, the myths about bamboo have come to stay due to the wrong way of using them. Any bamboo, however mature it is, if left to the vagaries of rain and sun untreated, will not last beyond a few years due to the high starch content. Local methods like cashew oil coating cannot be replicated everywhere and not everyone keen on using bamboo is aware of other treatments. People tend to think bamboo is cheap, which is not a fact always; hence discard the idea without looking at the value for money. Bambusa Arundenesia and Dendrocalamus Strictus are better suited for construction, yet we tend to use whatever is locally available and then blame the idea of building with bamboo itself. No wonder, though India is the second largest producer of bamboo in the world, most of the production goes to the paper industry, daily use objects, screens or temporary supports for construction.
The common comments against bamboo revolve around it being a fire hazard, which is partly true. However, the high silica contents of the surface wards off fire for longer time than timber and fire-proof chemical coatings can improve the performance comparable to any other material. The wall panels of bamboo are rather thin, just 2 to 3 inches only; hence do not assure sound-proof qualities.
Bamboo mats can be enmeshed within cement mortar, a simple method that improves both its fire retarding and sound-proofing qualities, but this has to be done carefully. Incidentally, all bamboo buildings require skilled workmanship and good working knowledge of the material. The joints can be very tricky, cut sections demand careful handling, while grooves, ropes and knots need to be complimenting the overall structure.
It is easy to justify why bamboo should be used. We can list reasons like economical in regions where it grows, lighter weight for the dead load calculations, faster in construction, faster re-growth of cut bamboos, hence regeneration of the material and such others.
However, the criteria to assess bamboo structures cannot be the same as those for timber, masonry or modern buildings. If we apply different yardsticks, case by case, then bamboo buildings will also get as accepted as are other mainstream buildings. To that end, we will have to follow the proper methods of building with bamboo.