Foundation challenge for supertalls

Malaysia has been reaching for the sky with the construction of supertall buildings in recent years. As skylines climb higher and higher, the conversation tends to centre on the visible aspects.

How tall is the building? What does the design represent?

The country’s vertical growth becomes even more striking when viewed in a global context.

Currently, there are eight completed buildings classified as supertall in Malaysia, defined as structures over 300m.

All of them are located in Kuala Lumpur (KL), making the city one of the most concentrated hubs of skyscrapers in South-East Asia. As of 2024, Malaysia ranks fourth in the world with the most skyscrapers after China, the United States and the United Arab Emirates, respectively.

Tall order milestones

The tallest is Merdeka 118, which rises to 678.9m, making it the tallest building in South-East Asia and the second-tallest in the world. Other landmark structures include The Exchange 106 in the Tun Razak Exchange district and the iconic Petronas Twin Towers, which remains the world’s tallest twin towers.

Few realise that the Petronas Twin Towers also hold a less visible distinction. Beneath their iconic silhouette lie some of the deepest foundations ever constructed for a building, extending to around 120m below ground.

Luxury residential and commercial towers such as Four Seasons Place, SO Sofitel Residences and Telekom Tower add to the the area’s density.

Beyond these supertall buildings, however, Malaysia’s high-rise footprint is even more extensive. The country has over 300 buildings exceeding 150m.

While the formal supertall threshold begins at 300m, numerous other towers just below that mark contribute to one of the most recognisable and vertically intense urban landscapes in Asia.

Having so many supertalls can be a prestigious affair that places Malaysia on the map.

The real story, though, actually lies beneath the surface. What is happening below ground?

Malaysia is sinking

With modern engineering comes more advanced foundation design. Today’s high-rises are built to withstand far more than just their own weight.

They must account for vertical loads, as well as lateral forces from wind and structural sway.

Yet the most defining challenge may lie in KL’s very name. Often translated as muddy confluence, it reflects the city’s underlying ground conditions where soft soils and limestone formations mean that buildings are not just built on land, but on ground that continues to shift over time.

Known as land subsidence, it simply refers to the gradual sinking of the ground. In Malaysia, the rates of subsidence can vary a lot depending on the region.

Generally, studies show that it falls somewhere between 0.5cm and 6cm per year. Coastal and urban areas tend to be the most at risk. For instance, in Selangor, subsidence averages about 1.33cm each year, with some areas experiencing up to 7cm.

On the flip side, northern states like Kelantan see much lower rates at around 0.42cm per year, mostly due to groundwater extraction for homes and businesses.

The impact of this slow sinking is already noticeable in our surroundings. When the ground sinks unevenly, it causes something called differential settlement. This means that different parts of a building may settle at different rates, leading to problems like cracked walls, uneven floors and misaligned doors. These issues are often seen in older homes.

But it is not just houses that are affected. Large infrastructure projects also face challenges. For example, the Kuala Lumpur International Airport (KLIA) is built on peatland, a type of soil that compresses over time.

This makes it crucial to monitor and manage the ground continuously to ensure everything stays stable over the long term.

The concern becomes even more complex when land subsidence is considered alongside rising sea levels, currently increasing at an estimated 0.3cm to 0.7cm per year. The combined effect of sinking land and rising water amplifies flood risks in low-lying coastal and urban areas, including Klang, Johor Baru and Shah Alam.

In this context, subsidence is no longer solely an engineering issue for individual structures. It is increasingly a wider challenge for flood resilience and long-term urban planning.

This is where foundation engineering becomes more than a structural discipline.

Rather than relying on standardised solutions, modern design depends heavily on site-specific analysis, advanced modelling and simulation to predict how soil and structure will interact over decades.

Each high-rise is increasingly treated as a unique engineering problem shaped as much by ground conditions as by architectural intent.

Evolution of building standards

Fortunately, Malaysia has made significant strides in its building standards.

After the headline-making 2015 Sabah earthquake, the Construction Industry Development Board introduced new guidelines stating that any high-rise buildings constructed from 2016 onward must be able to withstand earthquakes up to a magnitude of 7.0.

This is a big step toward more cautious design practices, especially for a country that is often seen as outside the major seismic zone called the Ring of Fire.

This shift also adds a whole new level of complexity to foundation design.

Engineers now have to consider not just the usual static loads and long-term ground settlement but also how structures interact with sudden dynamic forces that come from the soil.

Plus, many older buildings were built before these updated regulations. This means that the current built environment showcases a mix of different safety standards from various times.

So, the debate is not really about whether Malaysia can handle taller buildings anymore.

Thanks to the available engineering tools, the country has set some global benchmarks of its own.

The more pressing concern is ensuring that the same rigorous geotechnical standards applied to high-profile projects are also extended to all types of developments.

As Malaysia continues to build upwards, the deeper challenge lies in staying grounded and understanding what lies beneath.

Foundations are certainly not just structural elements hidden from view. They are actually complex systems that mediate between building and ground, managing forces, movement and uncertainty over time.

The strength of the skyline ultimately depends on how well that relationship is understood.