At least three out of four buildings in Nairobi would be seriously damaged in the event of a major earthquake, a new report on the state of construction in the city says.
The report by Questworks, a design and engineering firm, says contractors who steal cement and use less steel are to blame for most of the weaknesses. Architects and engineers also add to the exposure by failing to verify the quality of the works.
Raul Figueroa, a PhD student at the Carnegie Mellon University, studied Nairobi’s buildings over a period of three years and compiled the report that is due to be published in an international scientific journal.
“The non-destructive test (NDT) results suggest that most concrete used in Nairobi lack required compressive strength,” says the study, which tested 254 samples from 24 construction sites for office buildings, churches and universities.
The study found that the quality of construction work is poor across Nairobi, but was more alarming in less affluent parts such as Buru Buru and Eastleigh.
“In Eastleigh and Buru Buru 100 per cent of the buildings were unsafe,” the report says.
Buildings were randomly chosen from a pool that engineers and architects had certified as being structurally fit.
Data was then collected and used to make computer models of the buildings that were then subjected to a simulated earthquake to show what would happen in the event of a tremor.
The results of the study showed that a major earthquake would cause serious destruction of between 1,000 and 2,000 buildings. Most of the buildings would have to be demolished to pave the way for fresh construction.
The economic cost of such a destruction to the country is estimated at $3.5 billion (Sh316 billion), a 15-year development setback, loss of jobs and human life.
Mr Figueroa’s findings are in stark contrast to official reports that indicate 80 per cent of Nairobi’s buildings were constructed using concrete that meets or exceeds design strength.
The study found that lack of incentives for engineers and architects to properly supervise construction creates a tempting environment for contractors to cut corners.
Mr Figueroa also found a major dysfunction in Kenya’s construction industry that rewards those who do the least work more than those who actually sweat through the projects.
“Design work on average takes six months and accounts for 75 per cent of the professional fees while supervision takes two years yet accounts for 25 per cent of the fee,” the report says.
This payment plan results in architects and engineers spending more time looking for design work as opposed to supervising ongoing projects since it pays more and takes less time.
For contractors, cutting back on steel and cement was found to be the most profitable way to steal from a project.
The study found that cutting back on steel use enables contractors to pocket as much as $330 (Sh29,800) per 100 square metre of construction work and $300 (Sh27,100) for cement on a similar measure.
Overall cutting corners were found to account for up to six per cent of total project budget.
The National Construction Authority (NCA) said that while there was a possibility of some buildings having structural weaknesses, total collapse is usually the result of many factors and not just cutting corners during construction.
The NCA chairman Steven Oundo said poor design, cost cutting and lack of quality controls are other factors that may lead to structurally unsound buildings.
Mr Oundo, however, added that official reports that show a building is structurally strong when it is not are often products of foul play by contractors who cherry-pick building samples during testing surveys.
“The contractor may take one concrete cube specifically for testing,” said Mr Oundo. Other professionals said there have been cases of poorly constructed buildings but denied that most of Nairobi’s buildings are unsafe.
Lee Karuri, the chair of the Architectural Association of Kenya’s college of fellows, said any weaknesses in the buildings are the handiwork of ‘a few rotten apples’ but that the majority of professionals have developed structurally strong properties.
“It does happen but you will notice that all collapsed buildings in Nairobi have been traced to a consortium of incompetent professionals,” Mr Karuri said, adding that a large stock of buildings in Nairobi is still intact.
For buyers, the fraudulent and shoddy work has a cost implication.
The head of marketing at property manager, Hass Consult Sakina Hassanali has recently said that reworking newly built homes often result in contractors and developers adjusting their prices to maintain and ultimately pass the additional costs to end users.
Mr Figueroa, however, offered hope for Nairobi’s building owners, saying the structures can still be made stronger and disaster prevented.
The NCA, Strathmore University, Carnegie Mellon University, Hass Consult, Architectural Association of Kenya, the Kenya Property Developers Association and design firm Questworks Ltd are forming an advisory board that will come up with a better formula for auditing buildings.
The report comes at a time when Kenya is in a construction boom, especially in its major towns.
The Economic Survey 2014 shows that between 2013 and 2014 the value of plans approved increased by 34.2 per cent to Sh243.1 billion from Sh181.1 billion.
Nairobi accounted for Sh190.6 billion or 78 per cent of the approved buildings.