A «skyscraper» is a rather controversial term, as architects in different countries still disagree on how tall a building should be in order to be called a skyscraper. For example, in America and some European countries, skyscrapers are defined as buildings 150 metres in height or more. In Germany, a building in that status would have to be 100 metres or more above the ground (houses 35-100 metres high are simply called high-rise buildings). SkyscraperCity (Netherlands), one of the world’s largest and best-known construction websites, specifies a minimum height of 200 m for a skyscraper.

And some more terminology and numbers from the American Council on Tall Buildings and the Urban Environment (CTBUH), an international organisation specialising in high-rise construction:

  • buildings taller than 300 m are referred to super-tall skyscrapers;
  • Buildings over 600 m high are called ’mega-high’.

Where is the controversy coming from?

The differences in the classifications and rankings of high-rise buildings is due to the different ways in which the key parameters of buildings are measured in countries around the world. For simplicity, the criteria of the American CTBUH Council is now generally accepted: a building is a structure with storeys, designed for residential, commercial or industrial use. The presence of floors immediately excludes radio and television towers from this category.
The height is measured by the Council on the basis of three criteria ( the concept of height itself is defined from the lowest significant entrance of the building):

  • Constructive — the height from pavement level to the highest point of the structure, including spires but excluding TV, radio antennas and flagpoles. This is taken into account when including buildings in the ranking of tallest buildings.
  • To the floor level of the last exploited floor of the building.
  • To the highest point including spires and antennas.

A glimpse into the history of skyscrapers

Before the XX century buildings above six stories were difficult to find, since there was no lift, people had to use stairs to get to the right floor, which was very inconvenient. Another reason is the specifics of the water supply: before the twentieth century, suction pumps were used which could not deliver water more than 10 m above ground level.

The construction of skyscrapers, as they are now, was made possible by advances in building technology (steel, reinforced concrete), the advent of safe lifts, and the development of pressure water pumps. Increasing the height of buildings is particularly important in large cities, where building space is limited and land prices are high.

As a side note: buildings of +/- 200 m in height can only be supported by a central concrete-steel core, structures of higher height need to have additional external supports. That’s why skyscrapers use less than 70% of their interior volume — the remaining 30%+ is taken up by support structures, stairwells and lift shafts. By comparison, in conventional high-rise buildings, up to 80% of the interior space can be used.

One final interesting fact: the largest number of skyscrapers taller than 150 m are located in China, America, the UAE, Japan, Korea and Australia.