Nigerian building engineers have argued that the use of bamboo technology for the construction of houses in Nigeria has not been approved by the government and that some construction engineers who apply the technology may abuse it.
The reactions followed a viral video clip seen by THE WHISLTER where the technology was applied in a building under construction in a location that is reportedly in Anambra State.
In the video, the builders used bamboo in place of iron rods to reinforce the concrete slab, column and beams in the building.
THE WHISTLER interviewed four construction experts who gave divergent views on the sustainability of bamboo when used for construction projects.
In many countries in South America and South Asia, it is common to see builders use bamboo as a construction material, particularly in India, China, Bangladesh and Indonesia.
Folajomi Ibrahim is a construction expert who has experience in developing high-quality low maintenance properties. He said that there is no regulatory approval for the use of bamboo for such purpose in Nigeria.
Ibrahim explained that it is expected that for a construction site to be approved, the engineers must submit drawings and schematics of his projects to relevant authorities for approval.
He described the builders as people doing an expensive “experiment” which “doesn’t make any sense.”
Ibrahim said he is certain that no government agency would give approval for that type of experimentation.
He explained that “an average slab is about 150mm thick. That’s a solid slab. It has 20mm concrete cover at the top and 20mm cover at the bottom which is typical to most drawings I’ve come across by structural engineers.
“Now, it has 10mm running like this and 12mm running like this at the top and at the bottom. Top bars, bottom bars and now they have to be separate. So, you have 20mm at the top, 10mm, 12mm.
“You have 60mm to 66mm spacing in the middle to separate the top bars and the bottom bars because they’re not doing the same thing. Then, you have the top bars and the bottom bars that are 10mm and 12mm again. Then you have a concrete cover. Now, that’s a total of 150mm.”
Ibrahim said the size of bamboo is between 50mm and 150mm which would make the slab thicker if the standard concrete level is introduced.
He said bamboo is not strong when used as slabs, adding it may break. According to him, this fragile quality explains why builders use it in a vertical position.
Sharing his view, Mr. Edwin Onyeje, the founder of Knus Construction and Architect Ltd, argued that there is no design specifications yet for using bamboo for suspended slab, beams and columns for buildings.
Onyeje noted that the reasons why bamboos are not used in Nigeria is because it has different species and the characteristics of these species are not uniform.
He added that when using any material for construction, specific cautions are considered. For instance, the durability of the material, its ability to withstand pressure, fire outbreak, rainfall and adverse change in weather conditions
He said, “Now, talking about these design specifications, if you are using iron rods, as a reinforcement in your concrete, they have design specifications for it, but then for bamboo, this design specification does not exist yet, for that reason it cannot be used for this purpose now.
“Now, Bamboo has a tensile strength (maximum amount of load an object can carry) that supposedly would be good enough to serve as the reinforcement for a concrete. But why it’s not being used is that bamboo deteriorates in time. The characteristics, the tensile strength deteriorate with time.
“The life span of a building is 10 years, 15 years and so on, even if this bamboo is well preserved, it’s still wood. The chances that it would survive the attack of wood attacking pest for over 50 years is low. You are not just building a house to serve you for one year or two years. With time, the tensile strength, reduces, and every other characteristic of it reduces with time. Then this becomes a problem. In a sense that when you build your house, for example, the load of your building remains there the load on your building does not decrease with time with everything being equal.”
Onyeje said when pressure mounts on the building, it may be at risk of collapse.
Another building expert, Egunnaya Franklin Chinemerem, who owns Donatech Construction Service Ltd expressed a divergent view as he argued that bamboos are not as bad as people assume.
In his opinion, the use of bamboo is been critised by engineers in Nigeria and Africa who are not knowledgeable in the use of bamboo technology.
Unlike Onyeje, Chinemerem argued that the tensile strength of a bamboo outweighs that of an iron rod. But he clarified that in the context of construction, it is not all species bamboo that is suitable for building.
He said, “It’s safe, the tensile strength of bamboo is estimated at 30,000 pounds while the tensile strength of the iron rod used for decking is estimated between 23,000-25,000 pounds. So, bamboo is relatively stronger than the iron rod.
“However, not every bamboo is good for this, that fat and teen ones are not good but those small and mature sizes are okay, perhaps there are special species used for construction and they can be treated to withstand longevity. Also, the thickness of the deck is also enhanced using bamboo.”
He made an exception for the use of bamboo in areas like decking the last floor of a building because it will be exposed to rain, particularly for building that does not have sheet roofing.
He advised engineers to use sheet roofing, where bamboo is used for construction.
On the issue of building collapse, he said, “It depends on bamboo beams/pillars positioning. Some structures that lack pillars and adjusters or that the pillars are wrongly positioned will definitely fall regardless of the use of iron rod used.”