That buildings collapse in Africa is not a new phenomenon. Most affected countries include Nigeria, Kenya and South Africa.After a building collapsed in Kenya last week, leaving more than 40 dead, experts look at some reasons why such incidents occur in Africa.
While investigations are still underway into the cause of this collapse, we look at some common problems.
1. The foundations are too weak
Adequate foundations can be costly and most business persons look into cutting cost.
They can cost up to half the price of a building, observes professor of civil engineering Anthony Ede at Covenant University in Ota, Nigeria.
He says two things should be considered when you are building the foundations – the solidity of the soil and the heaviness of the building and its contents.
In the commercial capital of his country, Lagos, the swampy ground requires strong foundations. Far stronger than solid ground.
But he says developers save money that should be spent on foundations when building on the city’s swampy ground and many buildings have collapsed in Lagos as a result.
Even on solid ground, foundations need to be strong enough for the load.
Inadequate foundations for a four-storey building was one of three reasons given by investigators for a building collapsing in northern Rwanda in 2013 and killing six people.
2. The building materials aren’t strong enough
Most building have been falling just because they aren’t strong enough to withhold the load are used, says Hermogene Nsengimana from the African Organization for Standardisation, whose organisation met last month in Nairobi to discuss why so many African buildings collapse.
He suggests there is a market for counterfeit materials – going as far as to say that sometimes scrap metal is used instead of steel.
3. Workers make mistakes
Even when workers are given the right materials to make the concrete, they mix them incorrectly, says Mr Ede.
This results in concrete which is not of the sufficient strength to hold the load.
He accuses developers of cutting costs by employing unskilled workers who are cheaper than trained builders.
4. The load is heavier than expected
Mr Ede says a building collapses when the load is beyond the strength of the building.
He gives the example of asking a baby to carry a heavy box: “The baby will not be able to withhold the strain.”
Even if the foundations and the materials are strong enough for what they were originally built for, that purpose may change.
So, Mr Ede says, if a building was designed to be a home and is then turned into a library where boxes and boxes of books are piled up, the building may strain under the weight.
He says another reason why the load is often heavier than the original design is because extra storeys are added.
5. The strength isn’t tested
At all points of construction the strength of the building should be tested, says Mr Ede.
“You have to be strict,” he says, about policing building.
“The law says you must test. It’s the enforcement of the law which is the problem,” he says.
That’s a big problem, he says, when at every stage of construction there is someone with a strong motivation to save money or take money.
There are many physical reasons a building can collapse but only one driving motivation for that to happen, says Mr Ede. That’s money.
And for him this is the real reason buildings collapse – corruption.