A civil-engineering review of the subsurface dimension of Nigeria’s construction failures.

The November 2021 collapse of a 21-storey residential tower under construction on Gerrard Road, Ikoyi, killed 45 people, among them the developer Femi Osibona, who owned the project [1]. The subsequent coroner’s inquest attributed the failure to negligence by the agencies responsible for approval and supervision and found that the building’s density and setback violated Lagos State Building Regulations [2].

Public discussion centred on the visible causes: unapproved additional storeys, substandard materials, and the withdrawal of the structural engineering firm in early 2020, which stated it could no longer vouch for the integrity of the third tower above the fourth floor.

A prior and less-examined question concerns the ground itself: whether a high-rise residential load was compatible with Ikoyi’s subsurface conditions, which the engineering-geology literature has characterised for more than two decades.

This review argues that the Lagos building-collapse crisis has at least three dimensions and that the geotechnical dimension is the least discussed. Before material quality, permitting, and construction practice, there is a layer of soil that is frequently not tested to an adequate standard. In a coastal city built in part on reclaimed lagoon margins and loose marine sands, that omission carries a high structural cost.

Sustainable construction in this setting does not begin with material selection or energy performance; it begins with characterising the subsurface. Until geotechnical investigation is treated as a mandatory first step rather than a procedural formality, subsequent decisions about sustainable infrastructure rest on unverified assumptions.

I. The Scale of the Crisis

According to the Building Collapse Prevention Guild (BCPG), a Nigerian professional advocacy body that has tracked these incidents for decades, Nigeria recorded 640 building collapses between October 1974 and 9 January 2025, with Lagos accounting for 55.15 percent of incidents [3]. By May 2025, the BCPG had revised the count to 653 incidents and 1,616 deaths, with Lagos’s share at 55.28 percent [4]. By October 2025, a compilation by Nigeria Info FM citing the same BCPG data placed the cumulative figure at 679 collapses and more than 1,639 deaths, including 171 incidents in Lagos between 2011 and 2025 [5].

The annual figures were 62 collapses nationwide in 2022, 52 in 2023, and 47 in 2024 [3]; by October 2025, 37 had been recorded for the year [5]. In the first half of 2025, Lagos recorded at least six confirmed incidents that killed fourteen people [6]. On 28 October 2025, a four-storey building at 43/45 Coates Street, Oyingbo, Ebute-Metta, collapsed during the morning peak, killing at least two and trapping more than a dozen [7].

BCPG research indicates that between 2000 and 2021, Lagos recorded 167 building collapses, of which 78.4 percent were residential, 12.8 percent commercial, and 8.8 percent institutional [8]. The failures are therefore not confined to formal high-rise projects; they occur across the city’s housing stock.

Where the Collapses Cluster

The incident record appears consistent with concentration in two settings: reclaimed land along the Lekki–Lagos Island axis, and older building stock predating modern geotechnical practice. This spatial tendency is offered as a hypothesis rather than a demonstrated result; a formal spatial analysis of the BCPG dataset against surficial geology would be required to establish it. Both settings share a common subsurface vulnerability, described below.

II. What Is Beneath Lagos

Lagos lies within the eastern part of the Dahomey Basin in southwestern Nigeria. The surface succession is dominated by the Benin Formation (the Coastal Plain Sands), overlain in many places by Recent Alluvium and resting on older Cretaceous and Paleogene sediments [9].

Three subsurface conditions govern foundation design in the city.

1. The shallow subsurface is young, loose, and saturated. Oladunjoye, Ishola, and Oyedele (Discover Applied Sciences, 2024) applied Multichannel Analysis of Surface Waves (MASW), Cone Penetration Tests, and Standard Penetration Tests across three Lagos coastal sites. They identified very loose to loose sand horizons with shear-wave velocities (Vs) of 170 to 250 m/s and liquefiable sand layers at depths between 2.5 and 18.0 metres [10]. Under sustained saturation, structural loading, or cyclic dynamic loading, these loose sands can develop elevated pore-water pressure; when excess pore pressure approaches the total overburden stress, effective stress falls toward zero and the soil loses shear strength, behaving temporarily as a fluid.
2. Shallow foundations on Lekki Peninsula soils have low bearing capacities. A direct-shear study by Warmate and Nwankwoala (Current Trends in Civil and Structural Engineering, 2019) found that the Lekki Peninsula subsoil comprises a loose sandy layer about 4 metres thick overlying medium-dense sand. The analysis returned an angle of internal friction of 17 degrees with effectively zero cohesion in the upper layer, and recorded the water table at less than 1 metre below ground surface. Using a standard bearing-capacity equation, the authors calculated an allowable shallow bearing capacity of 55 kPa at 1.5 metres depth, with a predicted settlement of 74 mm under a 200 kPa load [11]. They recommended that, for any significant load, a deep foundation with a founding depth greater than 5 metres be used to transfer load into competent sand [11].
3. Reclaimed margins offer no exemption. Geotechnical work by Adebisi, Osammor, and Oyedele (Ife Journal of Science, 2016), based on 25 SPT and 35 CPT tests across Ibeju-Lekki, returned allowable shallow bearing capacities averaging 121 kPa between 1 and 2 metres depth [12]. The authors noted that while these capacities are adequate for low-rise development, heavier engineering loads require deep foundations, for example 600 mm diameter piles driven to a competent layer at 8 metres depth [12]. These limits make undocumented increases in a building’s height and weight above the original design particularly hazardous, because they load a foundation system sized only for shallow parameters.
4. The geotechnical imperative: the subsurface beneath much of the highest-value real estate in Lagos is among the least tolerant of unverified design assumptions, and that tolerance decreases as the degree of land reclamation increases.

III. The Geotechnical Investigation Gap

Nigerian practice diverges from international technical norms in its treatment of site investigation.

International codes. The International Building Code (IBC), Chapter 18, Section 1803, requires a geotechnical investigation and a written report for essentially every structure of consequence, with field inspection by a special inspector during construction [13]. The British Standards BS 5930 (site investigation) and BS 8004 (foundations) prescribe comparable sampling and laboratory procedures before foundation design is finalised.

What Nigeria has on paper. The Nigerian National Building Code (NBC), first issued in 2006, specifies a requirement for soil investigation; the limitations lie in enforcement and uniformity. A Guardian Nigeria feature reports that requirements vary between states and are often weakly enforced or absent [14]. The Standards Organisation of Nigeria (SON) has separately identified inadequate soil testing as a recurrent cause of structural failure [14].

What this looks like in practice. A 2022 Lagos State directive halted approvals for buildings above three storeys in Ebute-Metta, citing the soil and topography, the low water level and its effects, and the inability of structures in the area to bear loads above three floors [15]. A blanket height restriction of this kind is a regulatory response after the fact: the administration limited permissible density because individual developers were not designing to the site’s bearing capacity.

IV. The Ikoyi Case as a Geotechnical Problem

The Gerrard Road tower remains the defining case. Public accounts emphasised the developer’s permit violations and height extensions; the engineering interpretation centres on soil–structure interaction.

The Ikoyi peninsula sits on Coastal Plain Sands underlain by loose silty sands with documented liquefaction susceptibility, with liquefiable horizons measured at depths between 2.5 and 18.0 metres [10]. A high-rise on such a site requires a deep foundation system designed against site-specific subsoil parameters, with safety margins that account for loose horizons exhibiting shear-wave velocities of 170 to 250 m/s [10].

The Lagos coroner’s inquest, delivered in August 2022, identified three concurrent failures: the building’s density and setback violated Lagos State Building Regulations, the supervising agencies failed to enforce the code, and the structural failure was attributed to design errors and combined stress failure of the columns at the lower floors [16].

The inquest did not attribute the collapse to subsurface behaviour, and this review makes no such claim. The relevant point is narrower: a combined-stress failure at the lower columns occurs when applied loads exceed the assumptions of the original load path. Increasing storey count during construction without re-evaluating foundation capacity raises the vertical and shear demand on a soil–structure system that was not analysed for it. On a site with the parameters described above, the design margin the ground demands is precisely what such changes erode.

V. Good Practice

A defensible geotechnical workflow for the Lagos context has five stages, operating at project scale.

1. Site reconnaissance and desk study. Review of existing geological maps, borehole data from adjacent sites, and historical land use to determine whether the site occupies natural ground or recent, uncompacted fill.
2. Subsurface investigation. A subsurface investigation sufficient to support a formal Ground Investigation Report. Under BS EN 1997–1:2004, Section 2.1, complex projects and those on difficult coastal terrain fall within Geotechnical Category 3, which requires more rigorous provisions and quantitative analysis than routine testing. To resolve rapid horizontal and vertical variation in sand-to-clay transitions, standard practice follows the field guidance of BS EN 1997–2 and BS 5930, deploying a systematic grid of Standard Penetration Tests and continuous Cone Penetration Tests to define the subsurface profile before final foundation modelling.
3. Laboratory testing. Index properties (moisture content, particle-size distribution), shear-strength testing (triaxial or direct shear), consolidation testing where compressible layers are present, and chemical testing for groundwater aggressivity to concrete and steel.
4. Geotechnical report. A report stating allowable bearing capacities at relevant depths, calculated settlement predictions, and explicit recommendations on foundation type. For the variable Lagos coastal margins, site-specific analysis shows that near-surface loose sands have low allowable bearing capacities and high settlement under load [11][12]. The analysis therefore favours bypassing these weak superficial horizons: a raft foundation may suit standard multi-storey profiles, but heavier engineering loads require deep foundations to transfer stress into competent sand [11][12].
5. Independent verification. An independent special-inspector model, comparable to the IBC framework, to verify that the subsurface conditions exposed during excavation match those assumed in the design report [13].

VI. Relevance to Sustainability

Sustainability in civil engineering is frequently framed through surface measures: low-carbon concrete, recycled aggregates, and energy-efficient building envelopes. That work is important, but it sits above a more basic condition of structural sustainability: a structure is sustainable only to the extent that its foundation carries the full design load for the intended service life without premature intervention. Emergency retrofit or replacement represents a failure of that condition.

From a lifecycle perspective, sudden structural collapse is the limiting case of unsustainability. The embodied carbon in the cement, structural steel, and quarried aggregate is lost, together with the energy of manufacture, transport, and assembly. The 2021 Ikoyi tower had been under construction for roughly two years before failure, representing two years of materials, energy, labour, and freight rendered unrecoverable.

This connects directly to UN Sustainable Development Goal 11 (inclusive, safe, resilient, and sustainable cities), whose Target 11.5 commits signatory states to reducing the direct economic losses and mortality caused by disasters [17]. Consistent with that target, a design framework must treat sustainable infrastructure as inseparable from the subsurface geology that supports it.

VII. A Working Framework

At national and regulatory scale, a framework drawing on NBC 2006, BS 5930, and the IBC would have five elements.

Mandatory geotechnical triggers. Mandatory investigation for all buildings above two storeys, all public buildings, and all structures on reclaimed land regardless of height. SON, with the Council for the Regulation of Engineering in Nigeria (COREN), is the appropriate body to enforce this.

Geotechnical site classification. Classification of land into geotechnical zones (upland Benin Formation, recent alluvium, reclaimed fill, and similar) with default minimum foundation requirements per zone. Comparable systems exist among coastal authorities in the Netherlands and the United States.

Independent verification. Geotechnical reports reviewed by an engineer not engaged by the developer. The arrangement in which the developer funds the consultant and the laboratory creates a conflict of interest under which reports can be fitted to the design rather than to the ground.

Public access to records. A publicly searchable register of geotechnical reports, foundation designs, and collapse incidents. The BCPG database is a starting point; broader access would allow patterns to be identified that the current system obscures.

Capacity building. Strengthened graduate programmes and supported field laboratories to develop the talent base over time, reinforcing the engineering geologists already publishing internationally.

VIII. Conclusion

The Brazilian-built Water House on Kakawa Street, Lagos Island, was completed in 1875 and remains standing [7]. The Gerrard Road tower did not reach two years. Between those cases lies a long period of engineering practice in which site investigation ceased to be treated as the starting point.

The remedy is not technically exotic: the literature exists, the standards exist, and the professionals are available. What is absent is the institutional commitment to treat soil investigation as the first non-negotiable step in the construction sequence rather than the most negotiable. A structure is only as durable as the ground beneath it, and Lagos’s record over five decades demonstrates the cost of neglecting that principle.

Disclaimer: This article was written as an independent civil-engineering review of publicly available data, peer-reviewed literature, and verified news reporting on the Lagos building-collapse crisis. It does not constitute a formal forensic engineering opinion on any specific incident, and the author has no affiliation with any of the regulatory agencies, professional bodies, or projects discussed.

References

[1] “Implementing findings on Ikoyi building collapse,” The Guardian Nigeria, 24 January 2022.
[2] “Why 21-storey Ikoyi building collapsed: Coroner,” Premium Times Nigeria, 9 August 2022.
[3] “14 states recorded 47 building collapse cases in 2024: Report,” Punch Newspapers, 20 January 2025.
[4] “Nigerian building collapse Guild laments as deaths hit 1,616,” APA News, 8 June 2025.
[5] “Falling walls, failing standards: Nigeria’s 50-year battle with building collapses,” Nigeria Info FM, 10 November 2025.
[6] R. Adebowale, “Timeline: Six incidents, 14 deaths — Lagos building collapses in first half of 2025,” TheCable, 23 July 2025.
[7] B. Nwannekanma, “Building collapse and harmful renovation of distressed structures,” The Guardian Nigeria, 22 November 2025.
[8] Building Collapse Prevention Guild, “Quantifying frequent building collapse and disaster risk reduction in Nigeria,” BCPG Ikeja, 3 April 2024.
[9] R. O. Ogunleye, M. M. Oluwakuse, J. Ajidahun, T. O. Ale and A. Oluwakuse, “Sedimentologic characteristics and correlations of coastal plain sand and alluvium deposits within Lagos environs, southwestern Nigeria,” Arabian Journal of Geosciences, vol. 17, no. 142, 2024.
[10] H. T. Oladunjoye, K. S. Ishola and K. F. Oyedele, “Multi-parameters approach to assessment of soil liquefaction vulnerability in wetland areas of Lagos, southwestern Nigeria,” Discover Applied Sciences, vol. 6, 2024.
[11] T. Warmate and H. O. Nwankwoala, “Geotechnical indications and shallow bearing capacity analysis within Lekki Peninsula, Lagos using direct shear analysis,” Current Trends in Civil and Structural Engineering, vol. 1, no. 4, 2019.
[12] N. O. Adebisi, J. Osammor and K. F. Oyedele, “Nature and engineering characteristics of foundation soils in Ibeju Lekki area of Lagos, southwestern Nigeria,” Ife Journal of Science, vol. 18, no. 1, pp. 29–42, 2016.
[13] International Code Council, “International Building Code (IBC 2021), Chapter 18: Soils and Foundations.”
[14] C. Uwaegbulam, “How poor soil testing fuels Nigeria’s building collapse crisis,” The Guardian Nigeria, 9 March 2026.
[15] “Building Collapse: Lagos Stops Approvals For Structures Above Three Floors In Ebute-Metta,” Channels Television, 11 May 2022.
[16] “Ikoyi building collapse: Supervisory agencies were negligent, says coroner,” TheCable, 10 August 2022.
[17] United Nations Department of Economic and Social Affairs, “Goal 11: Make cities and human settlements inclusive, safe, resilient and sustainable,” Sustainable Development Goals Knowledge Platform.