Combating building collapse in Nigeria

By Alake Olaniyi

BUILDING collapse refers to the failure of a structure or any of its components. The causes are multifaceted, ranging from material defects, design flaws, and construction methods to environmental conditions and building usage. Although buildings are designed for longevity, recent frequent collapses in Nigeria have raised national concerns due to the resulting loss of investments, properties, and lives. Different perspectives exist on who to blame. Experts cite poor-quality materials, unskilled labor, and weak site supervision. The public attributes collapses to non-compliance with specifications and the use of substandard materials and incompetent contractors. Academics blame poor work ethics and lack of enforcement of existing laws. The media should focus on educating the public on building safety rather than sensationalizing disasters. Governments must empower planning authorities and simplify judicial processes to ensure accountability. Building collapses have become alarmingly frequent. Corruption in development control and planning approvals worsens the situation. These collapses have caused significant human and economic losses. Professionals blame quackery and encroachment on their responsibilities. Thousands of lives have been lost annually due to structural failures, undermining efforts to reduce housing deficits. Governments should enforce building codes and develop public enlightenment programs. Legislative support is also crucial to back these measures.

Major causes of building collapse: 1. Bad design  A bad design does not only mean errors of computations and drawings, but also a failure to take into account all of the loads (dead, live, wind and combined) that the structure will be called upon to carry, non-compliance with relevant code specifications, erroneous theories, reliance on inaccurate data, ignorance of the effects of repeated or impulsive stresses, and improper choice of materials or misunderstanding of their properties. The engineer is responsible for these failures, which are created at the drawing board. Poor quality control and quality assurance (QA/QC) on the part of various designers is also a major factor responsible for bad design. This factor will relegate the very best design to the worst design status. Design flaws include incorrect load assumptions, ignorance of material properties, and violation of code specifications. Poor quality control during design further worsens the problem. 2. Inappropriate use and modifications: Collapse is imminent, in a matter of time, when a building originally designed (and constructed for a private residential use is converted into public utility having a higher live load as in school, hotel, church, small or medium scale factory, hostel etc., without proper structural integrity evaluation by qualified professionals. This fact is probably what is responsible for the collapse in Abuja last month (June 19th) of a building that has housed two churches for five years. This is also the case when the constructed structure deviates from the designed; e.g., the removal of certain columns to bring about the introduction of load bearing walls.

This thus implies that a building stands the high risk of collapse whenever the design load for such a structure is exceeded in service. A building is also at risk when additional floor(s) is/are added without the prior appropriate structural integrity evaluation particularly when such additions have not been taken care of in the initial design. Buildings originally designed for residential use are often converted to commercial or public facilities without proper structural evaluation. Unauthorized structural modifications, such as removing load-bearing columns or adding floors, can lead to collapse. 3. Extraordinary loads: Extraordinary loads are often natural, such as repeated heavy rainfalls, or severe wild winds, or the shaking of earth tremor or earthquake (not common around here in Nigeria). A building that is intended to stand for some years should be able to meet these challenges. A flimsy flexible structure may avoid destruction in an earth tremor or quake, while a solid masonry building would be destroyed. Earthquakes may cause foundation problems when moist filled land liquefies. Natural events like heavy rainfall, windstorms, or minor tremors can trigger structural failure. Poor site planning exacerbates this risk.

4. Unexpected failure modes: Unexpected failure modes are the most complex of the reasons for collapse. Any new type of structure or even construction method is subject to unexpected failure, until its properties are understood. Sand filling to drive away lagoon water seemed the answer to acquiring more land area but the consequence of its effect could pose serious problem to lives and properties. The founding of pile foundations in sand-filled land is a reliable and well understood engineering solution. However, the sad experience has shown that the collection of the driven water together with the attendant adverse hydraulic effect could bring about ocean surge problems as being currently experienced at the Lagos bar beach. This problem has become a Herculean task requiring thorough understanding and huge financial implication. New construction techniques or reclamation practices may introduce unforeseen risks. For instance, the effects of ocean surges at Lagos Bar Beach due to sand-filling practices show the dangers of misunderstood environmental impacts.

5. Foundation failure: Even an excellently designed and constructed structure will not stand on a bad foundation. Although the structure will carry its loads, the earth beneath it may not, due to inadequate soil bearing capacity. Bearing capacity of a soil is the ability of the soil to withstand load from structural foundation without failing by shear. The non-undertaking of site investigation and the use of inaccurate data on the soil parameters have contributed significantly to collapsed buildings in the country. Moreover, soil stress-inducing processes like heavy vibration, consumption activities, bomb explosion, mining activities, etc. could also bring about foundation failure. Even well-designed buildings collapse if built on weak soil. Inadequate soil investigation, seismic activity, or nearby construction vibrations can undermine structural stability.

6. Poor Quality Control (QA/QC)

In engineering design, consumption and manufacturing, quality control or quality engineering is a set of measures taken to ensure that defective products or services are not produced, and that the design and consumption meet the performance requirements. Quality is also the degree of fulfillment of interested parties’ reasonable expectations.

It is, with respect to concrete production, the supervision exercise on site to ensure that the materials used are of the required quality and that the mix proportions are adhered to as closely as possible.

Substandard materials, improper mixing of concrete, lack of curing, and deviation from recommended mix designs weaken structures. Common issues include segregation, bleeding, and improper bonding.

7. Cement and Aggregates Cement composition today often lacks the binding strength seen decades ago due to poor regulation. Rebagging and counterfeit products worsen quality. Similarly, weak or improperly graded aggregates result in low-strength concrete.

The use of poor quality aggregates has resulted in poor quality concrete which is responsible for some of the collapsed building cases witnessed so far.

8. Substandard Reinforcement Rods Reinforcement bars often fail to meet standard yield strength. Mislabeling coated mild steel as high-yield bars leads to under-reinforced structures.

The structural implication of this is that the produced reinforced concrete will not be adequate to withstand the expected design load, and so collapse is imminent in just a matter of time.

9. Water Quality Water is added to cement for setting and hardening due to hydration reaction that takes place within the cement paste. It facilitates mixing, placing and compacting of fresh concrete and also used for washing aggregates and curing purposes

Impure water used in concrete mixing affects hydration and durability. Chlorides and sulfates can corrode reinforcement bars, weakening the structure.

10. Corruption and Public Perception The corruption factor which is prevalent in our economy and polity is responsible for the above problems. The Nigerian public is made up of all of the principal parties like Government, Professionals, and Clients etc. It is the reason why a prospective client will want to achieve the maximum possible with the least cost, at the expense of safety (a function of quality in all its\ ramifications and durability. Such a client will engage a quack engineer that will produce sub-standard designs and quack builder that will compromise on all facets of the construction after paying his way through to influence even the approval procedures from the relevant government authorities.

Enlightened citizens often overlook building regulations for personal gain, while the uninformed remain unaware. Corruption across planning approvals, material quality control, and construction oversight worsens the problem.

Proposed Solutions

1. Cultural Shift in Mindset: Nigerians must embrace integrity, honesty, and accountability in construction processes. Corruption and the pursuit of short-term profit should be replaced with a culture that prioritizes safety and sustainability.

2. National Monitoring Agency An independent agency, similar to the National Construction Safety Team (NCST), should be established to oversee construction processes, material quality, and professional conduct. It should:

•             Ensure engagement of qualified professionals

•             Harmonize responsibilities among construction professionals

•             Improve building design, maintenance, and usage

•             Recommend updates to building codes

•             Prosecute offenders and forfeit unsafe structures

3. QA/QC Enforcement in Design and Construction All structural, electrical, and mechanical designs must undergo strict QA/QC checks. This includes compliance with codes, consideration of extraordinary loads, and fire safety provisions.

4. Mandatory Structural Integrity Evaluations Before any change in building use, deviation from original design, or addition of floors, professionals must conduct thorough evaluations to ensure structural integrity.

5. Site Investigations In line with BS 5930, soil surveys must assess site suitability, groundwater levels, and potential impacts on neighboring structures. This is crucial for both new and existing buildings.

6. Quality Control in Materials

•             Concrete: Proper mixing, placing, curing, and testing (slump test, cube test) must be ensured. Segregation and bleeding should be avoided.

•             Cement: Government must regulate production and prevent rebagging. Monitoring should be more stringent than current NAFDAC practices.

•             Aggregates: Aggregates should be tested for strength, porosity, deformation, and durability.

•             Steel Reinforcement: Standards should be enforced. Tensile tests must confirm the bar’s strength and diameter.

•             Water: Only potable water should be used. Regular water quality testing is necessary.

Conclusion: A building project is only as strong as its foundation, design, materials, and the professionals involved. From conception to completion, every stage must be handled by competent personnel guided by integrity and professionalism.

Government at all levels must enforce building regulations, prosecute offenders, and raise public awareness. Reports from panels of inquiry should be published to guide future prevention efforts.

Professional bodies such as the Nigerian Institute of Building (NIOB) and Nigerian Society of Engineers (NSE) must lead the advocacy for regulatory reforms and ensure only qualified individuals participate in the construction process.

Ultimately, Nigerians must embrace a culture of honesty and responsibility to stop the devastating trend of building collapse.

                •Dr. Olaniyi is Acting Head Department of Building, School of Environmental Technology, Federal University of Technology, Akure.

READ ALSO: Only professionals can curb building collapse in Nigeria — NIA