How the Burj Khalifa was built on sand and so fast: the 192 piles, the buttressed core, the concrete pumped 600 metres, the spire and the 2009 bailout that gave it its name

Architecture · 4 September 2026

The Burj Khalifa in Dubai was built between January 2004 and January 2010, 828 m (2,717 ft) high with 163 floors, the tallest building in the world by 300 m over anything before it, designed by Adrian Smith with the engineer Bill Baker at Skidmore, Owings and Merrill in Chicago and built by Samsung C&T of Korea with Besix of Belgium and Arabtec of Dubai, for Emaar Properties; it stands on 192 concrete piles 1.5 m across driven 50 m into the soft sandstone under the sand and a concrete raft 3.7 m thick, its structure is a "buttressed core", a hexagonal concrete core braced by three wings in a Y that the wind cannot make sway in rhythm, its 330,000 m³ of concrete were pumped to 606 m, a record, at night with ice in the mix so it would not set in the desert heat, and its 200 m steel spire was assembled inside the top and jacked up through it. It was built in six years by 12,000 workers, most of them South Asian, at a cost of 1.5 billion dollars, and it was to be called Burj Dubai until the emirate's debt crisis of 2009 was met by a 10-billion-dollar loan from Abu Dhabi, whose ruler, Khalifa bin Zayed, it was named for on the day it opened, 4 January 2010. Below: the design, the foundations and the sand, the wind, the concrete, the core and the spire, the skin, the workers, the money and the name, the numbers and the myths, with the tower's ancestors in the first skyscraper and its rivals in the tallest buildings in the world.

The design: a desert flower with a buttressed core

Emaar, the developer of Downtown Dubai, held a competition in 2003 and chose SOM's design of a tower whose plan is a Y of three wings around a central core, taken, Smith said, from the six-petalled Hymenocallis flower of the desert and from the geometry of Islamic architecture; as the tower rises, the wings step back in a spiral, 27 setbacks in all, each one a terrace, so that the plan shrinks and the tower tapers to a spire. Baker's structural idea, the "buttressed core", is what made 828 m possible in concrete: a hexagonal core of walls carries the three wings, and each wing's walls run to its tip as a buttress, so that the three wings brace the core and the core braces the wings, the whole a stiff Y that resists bending from any direction; the outriggers at the mechanical floors tie the columns at the wings' ends to the core, and the structure is reinforced concrete to level 156, at 586 m, the tallest concrete structure ever, with structural steel only in the spire above. Smith left SOM in 2006 and later designed the Jeddah Tower, which was meant to pass it; Baker got the Fazlur Khan medal. Burj Khalifa.

The foundations: how it stands on sand

Dubai is sand on the surface, but not far under it: the borings found a metre or two of sand over weak, cemented calcareous sandstone and siltstone, "weak rock", down to 50 m and more, with groundwater full of salt and sulphates that attack concrete; there is no bedrock within reach, and the tower does not stand on rock but on friction. The foundation is 192 bored piles, 1.5 m in diameter and 43 to 50 m deep, drilled and concreted in the sandstone so that the friction along their sides carries the load, tested to 6,000 tonnes each, topped by a reinforced concrete raft 3.7 m thick under the tower's footprint, poured in 2004 in four sections of 12,500 m³ each with the concrete kept below 30 degrees; the concrete of the piles and raft was a dense, low-permeability mix with a cathodic protection system of titanium mesh and current in the raft to stop the salt corroding the steel. The sand was never the problem, the salt water was; the tower has settled about 60 mm, as calculated, and the Empire State, which sits on Manhattan schist, could not have been built here without the same piles.

The wind and the Y

The enemy of a tall thin tower is not the push of the wind but its vortices: as wind flows past a tower it sheds eddies alternately from each side, and if the eddies come at the tower's own frequency the tower sways in resonance, which is what wrecked the Tacoma Narrows bridge and is what limits height. The Burj was tested in the wind tunnel in Ontario in more than 40 models, and its shape was tuned to confuse the wind: the Y plan gives no flat face, and the 27 setbacks, in a spiral, change the width at every level, so that the vortices shed at different frequencies up the tower and never add up; the tower was also turned on its site so that the prevailing wind hits it at the angle that least excites it. The result is that the top sways about 1.5 m in a strong wind, slowly, without a tuned mass damper, which the Taipei 101 needed, and the design wind, the 50-year storm, was set at 55 m/s; the tower has stood through the shamal winds and the storms since with no reported problem.

The concrete: pumped 600 metres at night

• The mix. High-strength concrete of 80 megapascals, with fly ash and silica fume, designed to be pumped and to stay workable in heat; the mix for the raft had 13 per cent less water than normal, and the mix for the core had a "self-consolidating" flow so it needed no vibration in the crowded reinforcement.
• The heat. Dubai's summer is 45 degrees, and concrete that sets hot cracks; so the concrete was mixed with ice instead of water, at night, and poured between midnight and dawn, and the raft was cooled with pipes.
• The pumping. Putzmeister pumps at the base pushed the concrete up a single pipe to level 156, at 606 m, in one lift, at pressures of 200 bar, a world record; it took 40 minutes for the concrete to reach the top, and the pipe was cleaned by a sponge ball each time.
• The volume. 330,000 m³ of concrete, 39,000 tonnes of reinforcing steel, 110,000 tonnes in the tower in all; the concrete would fill a pipe 2,065 km long.
• The core. Built with an Australian jump-form system, hydraulic formwork that climbed the core walls and lifted itself, so that the core rose one floor every three days at the peak and the floors followed, cast in place on the wings; the tower gained a floor in three days for two years.

The spire and the top

Above level 156 the tower is a steel spire of 200 m, a braced tube of 4,000 tonnes with a telescopic top, which was assembled inside the tower at the top of the concrete, in 2008, and then jacked up through the roof by hydraulic jacks in stages over four weeks, the way the Chrysler Building's spire was raised in 1929, until its 143 m protruded; it holds the telecommunications equipment, the mechanical floors and the tip that makes the height, and it is the reason the height is disputed, since 244 m of the tower's 828 is uninhabited, the "vanity height", the largest of any building. The tower topped out at 818 m on 17 January 2009, and the spire's final section made 828; the highest occupied floor is 160, at 585 m, the observation deck At the Top on 124 and 125 at 452 m and the Sky deck on 148 at 555 m, the highest in the world when opened. The tower's height had been secret until the opening, so that no rival could plan to beat it; it beat the Taipei 101's 508 m by 320 m, the CN Tower's 553 m as the tallest structure, and the KVLY mast's 629 m as the tallest anything.

The skin, the inside and the workers

• Cladding. 26,000 panels of reflective glass and aluminium, 142,000 m², designed for the desert: silver-coated glass that reflects the sun, and vertical stainless-steel fins that shade it and give the tower its texture; installed at 20 to 30 panels a day from 2007 to 2009, and cleaned by a crew of 36 with three machines on tracks, over three months per cycle.
• Inside. The Armani Hotel on floors 1 to 8 and 38 to 39, 900 apartments to floor 108, offices above, the Atmosphere restaurant on 122, mosques, pools on 43 and 76, and 57 elevators, the double-deck ones at 10 m/s and the longest lift run in the world, 504 m, in one shaft; the tower's water system delivers 946,000 litres a day, and its condensate from the air-conditioning fills a lake's worth a year for the gardens.
• Workers. About 12,000 on site at the peak, from India, Pakistan, Bangladesh, Nepal and the Philippines, housed in camps in Sonapur and bussed in, on wages of about 4 to 7 dollars a day; in March 2006 about 2,500 workers rioted over pay and buses, and in 2007 there was a strike; Human Rights Watch reported the conditions, and the developer reported one death on the project, of a worker who fell in 2007, against the guess of others that there were more.

The money and the name

Emaar's budget was 1.5 billion dollars for the tower and 20 billion for Downtown Dubai around it, with the Dubai Mall, the fountain and the lake; the tower was sold off-plan in 2004 and 2008 at the peak of the boom, at up to 40,000 dollars a square metre. In November 2009, six weeks before the opening, the state company Dubai World asked to delay 26 billion dollars of debt, the property market having halved, and the emirate faced default; Abu Dhabi, the richer neighbour and the capital of the UAE, lent 10 billion in December, and on the opening night of 4 January 2010, at the end of the fireworks, the ruler of Dubai, Mohammed bin Rashid, announced that Burj Dubai would be Burj Khalifa, for Sheikh Khalifa bin Zayed, the president of the UAE and ruler of Abu Dhabi; the signs and the website were changed overnight, and the name is the price of the loan. The tower was 90 per cent empty of tenants in its first year; it is full now, and its observation decks, at 40 to 100 dollars a ticket, take a million and a half visitors a year.

The numbers

• Height. 828 m (2,717 ft) to the tip; 829.8 m by some measures; 163 floors plus 46 maintenance levels in the spire; highest occupied floor 585 m; observation decks 452 and 555 m.
• Records. Tallest building, tallest structure, tallest freestanding structure, most floors, highest occupied floor, highest observation deck, longest lift run, tallest concrete structure, highest concrete pump, since 2010; the Jeddah Tower at 1,000 m, begun in 2013 and stalled since 2018, resumed in 2025.
• Foundations. 192 piles, 1.5 m across, 43–50 m deep; raft 3.7 m thick, 12,500 m³ per pour.
• Materials. 330,000 m³ of concrete, 39,000 t of rebar, 4,000 t of steel in the spire, 142,000 m² of glass in 26,000 panels, 15,500 m² of stainless steel.
• Time. Excavation January 2004; foundations to February 2005; tower 2005–09; topped out January 2009; opened 4 January 2010; 6 years.
• Cost. About 1.5 billion dollars; the whole Downtown development 20 billion.
• Workers. 12,000 at the peak; 22 million man-hours; one death reported.
• Weight. About 500,000 tonnes; the tower sways 1.5 m at the top; it has settled 60 mm.
• Lifts. 57, plus 8 escalators; the fastest 10 m/s; 504 m in one run.

Versions and theories

• It stands on sand, so it will sink or fall. It stands on 192 friction piles in sandstone under the sand, which carry it as bedrock would, and it has settled 60 mm as designed; every tall building in the Gulf is founded this way.
• It has no sewage connection and trucks carry the waste. True of Dubai's boom towers in 2009–10, when the sewage plant could not keep up and tankers queued for a day at the treatment works; the Burj was connected to the city system when it was finished, and the trucks were the neighbours'.
• Its height is a cheat because of the spire. The spire is structural and counts by the rules of the Council on Tall Buildings; the 244 m of unoccupied "vanity height" is the largest of any building, and the highest floor at 585 m is still higher than any other building's tip except the Merdeka 118's.
• It was built by slaves. By migrant workers on low wages in a system of sponsorship that human rights groups have called forced labour in some cases; the wages were paid, the workers came voluntarily, and the conditions were the ones reported by Human Rights Watch in 2006, which led to reforms on paper.
• It was named for Khalifa because Abu Dhabi bought it. Abu Dhabi lent Dubai 10 billion dollars in the crisis of 2009 and the name was announced at the opening; the loan did not buy the tower, and Emaar owns it.
• It can be seen from 95 km. On a clear day from the desert or the sea, yes, and its shadow crosses the whole of Downtown; the tip is visible from Sharjah and from aircraft over the Gulf.

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