6 Most Common Reasons Why Building Collapse

1. Wrong foundation Type

The foundation is the lowest part of the building or civil structure that is in direct contact with the soil.   It transfers the load of the building or the structure safely to the soil beneath. In other words, it receives the load of the building and transfers it safely to the lower soil strata without extreme settlements. If the foundation of a building is laid without understanding the ground conditions below, it can lead to foundation failure. Therefore, the first and foremost part of constructing any building is laying a strong foundation upon which the strength, durability and resilience of your project will depend. During construction, this part requires a lot of attention to detail.

Unfortunately, some folks determine their foundation type and size irrespective of the height of the structure they intend to build without any professional consultation and scientific calculations.

One does not just come and start erecting a house without examining the soil to determine the soil-bearing capacity of that particular piece of land. It is the soil-bearing capacity of the soil that acts as a major determining factor in deciding the foundation type of a building. You don’t by yourself determine the foundation type that suits the particular structure that you intend to erect; it has to be determined scientifically through the right pieces of equipment and gadgets.

The foundation you use for a Storey building is different from the one you use for a two-story building. If you’re going further, say to a three, four or five-Storey building, the foundation type has to be calculated and determined, otherwise, the building may have a problem in the near future.

In a state like Anambra State, there’s a government agency established by the law to carry out the soil-bearing capacity of your land and also to test the different building materials which you bought for your project to ensure they’re up to standard. They do this at a material testing laboratory built by the government – although, they do this at your own expense.

A building is a concrete immovable structure, when its foundation has a problem, there’s virtually nothing anyone can do especially when it involves a large structure. That’s why you see some abandoned buildings due to faulty foundations. Most of the time, the only solution is to demolish the structure and start afresh especially when they’re large structures.

You may also like to read – Building Foundations

• Wrong structural design

We’ve seen some folks who know nothing about the structural arrangement of a building going into the construction business perhaps because their uncle or cousin is a government official or became a governor or a minister. There’s a drawing that is called “structural drawing” in construction. It is the drawing that specifies the dimensions, positions, numbers of bars, spacing, links, diameters of bars, bending schedule and quantity of reinforcements required for a particular building. It also shows the various structural layouts of the beams, slab, staircases and their detailing.

Also accompanied by the structural drawing is the calculation sheet which shows how the final output of the design was calculated. The calculation sheet helps the Engineer to re-verify the authenticity and the accuracy of the design. Unfortunately, some people go into the construction without a well-designed structural drawing or structural drawing at all.

An inexperienced engineer or a quack builder sometimes produces a structural drawing that is insufficient or inappropriate for the said structure. The most common design and detailing errors committed by these folks are; Insufficient reinforcement at corners and openings, inadequate provision for deflection, insufficient travel in expansion joints, unanticipated shear stresses in piers, columns, or abutments, inadequate joint spacing in slabs, inadequate quantity of reinforcement, lengthy beam expansion, wrong choice of bar, lengthy spacing between links, etc.

Due to inadequate structural design, the concrete is exposed to greater stress than it can handle or strain in concrete increases more than its strain capacity and fails.

You may also like to see – Fine Examples of Structural Drawing

• Wrong mix ratio

Concrete mix ratios are the suitable proportions of concrete components such as cement, sand, aggregates and water prepared to meet the required strength and durability of a concrete structure. These mix ratios are decided based on the type of construction and mix designs.

The choice of a concrete mix depends upon the types and quality of work; it also depends upon the load coming on the structure formed and climatic conditions.

There are three major types of concrete mix ratios; Nominal mix, standard mix, and design mix. Different Grades of Concrete denote their strength for a required construction. The “M” denotes mix. For example, if the concrete mix is of M20 Grade then the compressive strength will be 20 MPa.

The following table shows an example of a nominal mixed ratio and its compressive strength at 28 days.

There are some instances where you may have a good structural design, but if the mix ratio is wrong, it can ruin the structure. Sometimes, you still need to test the compressive strength of your mix ratio. The compressive strength of a mix ratio is tested in a laboratory using special testing pieces of equipment and gadgets.

Results of investigations of many building collapse and other failures have been traced to poor quality concrete and concrete materials which affect the strength development, durability properties, and thus the in-service load-carrying capacity of the structural elements.

• Use of Substandard building materials

There are some cases of building collapse where the problem is the quality of building materials supplied. Almost everything in the construction industry has real and inferior or substandard parts, especially in developing nations like Africa. For example, 70% of the 16mm reinforcement rods in African markets are less than the actual diameter, the same thing applies to every other size. So, if the design recommends a complete 16mm and you’re using something less, it could affect the structure.

There are a lot of local stones available in the African environment. You don’t use them in a place that requires pure structural work. They could fail. The same thing applies to cement. The inferiority starts with the shortage of the supposed quantity of that material. Let’s take cement for example, they could write 50kg on the bag of cement, but what it contains is actually 42kg of cement. It is also in developing countries that we began to hear some new terms such as “re-bagging”. The term is used to refer to a material whose quantity has been tampered with or re-bagged. Most building materials are re-bagged either in quantity or in quality.

One must be careful about the source of their building materials to avert the purchase of substandard products. In Nigeria for example, surveys carried out have shown that the use of substandard building materials and corruption in the building industry have contributed immensely to most of the recorded cases of building failures.

• Use of inexperience careless workers

In Nigeria, stakeholders in the construction industry have said that the stock of competent skilled construction workers is rapidly dwindling with a 15 per cent annual decline of artisans in the sector. The get-quick-rich syndrome that is currently ravaging our youths has caused a lot of them to not pay attention and stay long enough with their masters to learn the work properly. They come out half-baked and start sourcing for their own job, or they follow other fetish means to make money overnight.

I’ve seen careless iron filters that cannot bind two reinforcements together effectively. I’ve seen bricklayers who cannot produce a straight line of well-bound blockwork.

An overlooked careless work from an unskilled inexperienced worker can cause the collapse of a building. Thus, the construction industry needs thorough supervision of workers to ensure they’re doing the right thing at every moment and stage of the construction process. Some stakeholders in the industry have called for the training and re-training of workers to reduce the incident of building collapse.

• Poverty

Poverty is one of the major problems in many developing countries. I’ve seen some folks who think they can handle the building of their houses without consulting a professional. They decide the foundation type they wish to use, where their columns are going to be placed, and decide the reinforcement diameter and quantity. Almost all their decisions are based on cutting costs. And they would always refer to a friend of theirs who spent only $5,000 to build an upstairs (a story building).

There is no such thing as “manage” when you want to erect a solid structure that will withstand time. There must be a structural analysis. In building a structure, or a structure with a suspended slab, one does not economize safety or practice short cut. You cannot eat your cake and have it.

We’ve seen some cases where the client would force their Engineer to ‘manage’ and cut costs in places that require serious reinforcements. Sometimes, it is good to cut costs but not at the expense of the structure.

Conclusion

The 6 most common causes of building collapse are; wrong foundation type, wrong structural design, wrong mix ratio, use of substandard building materials, use of inexperienced careless workers, and poverty.

If you find this informative, please don’t forget to share. If I have missed any information that is relevant to building collapse, you can mention it in the comment section below. Thanks.

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