If every construction was a small single storey dwelling to be built on level soil, which is not predominantly clay or rock, you might not need an engineer to design the foundation. But we don’t live in a perfect world, with perfect conditions. And so, it is best to hire a registered engineer because designing a foundation is a specialised task.
The importance of using a registered engineer to design your foundation
You would not like to drive over a bridge that was not properly designed by an Engineer and so, safety is always paramount. When it comes to construction, our first focus is often practicality, that is, what we need that has prompted the construction, and aesthetics, namely, what it will look like. Yet construction is not about the trend of the day. It must be durable. Even more importantly, it must be secure.
By definition, a foundation is the lowest load-bearing part of any construction. If it’s not strong enough to carry that load because of factors such as the nature of the soil or the angle of the site or the type of structure being built, the building is in danger of partial or total collapse.
In the last 50 years, documented until July last year, 181 buildings have collapsed in 51 nations. These stats do not distinguish between those building disasters caused by natural hazards such as earthquakes and those by technological hazards such as substandard construction. Whatever the cause, an average of eight building collapse disasters happen every year around the world, leading to 343 deaths per year. Most buildings collapse in India (32), followed by China, Egypt, Brazil and Nigeria (12 or 13 each). That is why it is necessary to bring in a registered engineer to take control of the foundation. The additional expense can save lives.
Unfortunately, a bad foundation will more than likely show itself when the building or dwelling is finished or nearly finished, however there is usually not much that can be done about it.
Professional engineers registered with the Engineering Council of South Africa have the know-how to deal with less than perfect scenarios. They recognise and assess what they are presented with and in a case where they are not hundred percent certain about the condition of the soil, the engineer can make use of a geotechnical engineer or do a full depth sample to ascertain the condition or type of soil through the foundation. When it comes to the soil and the desired construction, they can also take steps to address challenges, and hopefully, in a way which is cost-effective – financially and timewise.
Designing a foundation is about creating a construction plan. The foundation must support the building and the foundation design has to consider what is on both sides of it – the ground below the foundation, and the design and materials that will be on the foundation, which is usually made of concrete. What the engineer cannot design is if the contractor or builder does not follow his recommendation and or use substandard materials or is prone to bad workmanship.
Engineers have to make crucial decisions. These can include deciding whether there is a need for retaining or loadbearing walls, which serve to keep soil in place at different levels on either side of the walls and can help even out sloping properties and control water runoff. In certain cases, Pilon’s might be prescribed to ensure anchoring the structure to bedrock.
They also have to evaluate the soil: how much load it can take, and its moisture content. Whatever the soil type, they need to create a stable structure. If the soil is too sandy, it might require densification and if the soil is clay that will expand or shrink with the varying seasons, this requires other measures that need to be put in place.
The engineer’s job also involves assessing whether the foundation design needs to extend to a deeper and stronger level of the soil.
Ultimately, designing a foundation is complex and engineers need to be flexible. If during the construction process, the ground turns out to be different from the initial report and investigation, they must be prepared to adapt the design.