"After a building collapsed in Kenya last week, killing at least 33 people, experts look at some reasons why such incidents occur in Africa.
The six-storey residence in Kenya's capital Nairobi came down in heavy rain, with more than 80 people still missing.
While investigations are still underway into the cause of this collapse, we look at some common problems.
1. The foundations are too weakAdequate foundations can be costly.
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."
Read about the other 4 reasons building collapse.... BBC News