Sandy soil, shallow foundation, weak concrete mix and overloading are some of the factors that might have precipitated the recent collapse of a three-storey building at No 14, Massey Street, Ita-Faji on Lagos Island, an inter-ministerial committee set up by the Federal Government has said.
In a presentation submitted to the Minister of Science and Technology in Abuja on Friday, the committee chaired by the Acting Chairman, Nigerian Building and Road Research Institute, Prof Samson Duna, also listed low average comprehensive strength in the reinforced concrete as one of the causative factors.
On March 13, the three-storey building that housed among other a primary school collapsed, causing the death of 20 people while leaving many others injured.
Consequently, the Minister of Science and Technology, Dr Ogbonnaya Onu, set up an inter-ministerial committee to look into the causes of the building collapse as well as the causes of two other buildings that collapsed in Lagos and Ibadan about the same time.
In the report, Duna said, “The committee is of the opinion that the structure (at Ita-Faji) might have collapsed as a result of the following: the sandy nature of the soil with low bearing capacity, shallow foundation, weak concrete mix, low average comprehensive strength in the reinforced concrete and the overloading of the building resting on a small area by converting the second floor into a school.”
It noted that there was no set-backs on the adjoining structure at the right hand side as the structures were built wall-to-wall.
The report also noted that the average strength for the reinforced concrete elements were below minimum designed strength as revealed by the laboratory test conducted by NBBRI.
The committee also examined the causes of a building collapse at Sogoye, Bode Area (along Molete/Bere Road) in Ibadan, Oyo State as well as the one that occurred on No 54, Kakawa Street, Lagos.
On the Ibadan building collapse, Duna said, “Following the findings by the committee at the site and laboratory tests results, the committee came to the conclusion that the building collapsed due to non-adherence to the building construction process inappropriate/poor designs, hasty construction work, non-supervision of the construction work by professionals, and non-monitoring by the development control authorities.”
Duna said on the Kakawa building, “The set-backs provided were not adequate. The tests results show that the average comprehensive strength of the concrete was below the minimum standard.
“In view of the low comprehensive strength of the concrete, the building could not sustain the load imposed on it. Thus, it collapsed.”
The committee asked the Federal Government to advise the Lagos State Government and all other states with coastal cities to undertake integrity tests on all buildings within the cities and other areas necessary with a view to preventing reoccurrence of such collapses.
“Government, through public-private partnership, should embark on urban renewal programmes in our ancient cities so that old and dilapidated buildings and infrastructure which pose threat to health and safety can be replaced,” the committee recommended.
It recommended that all approved buildings should be subjected to integrity test after 10 years and subsequently every five years. It also asked the government to put a legislation in place to compel property owners to subject their buildings to integrity test.
The committee recommended that modifications to existing buildings should only be carried out by a team of building industry professionals where permissible by statute and bye laws.
It added, “Any alterations should be approved by the relevant government agencies before their implementations. Illegal conversion of buildings and non-use of relevant professionals for modifications in the sizes and heights often lead to deficiencies, failures and collapses and should be avoided.”
The committee also advised that developers who refused to implement their approved building plans and construct defective structures should be brought to book for the violations while the structures should be demolished to serve as deterrent to others.