It gives new meaning to the phrase "the sky's the limit."
Construction of the world's first kilometre-high tower is now under way in Jeddah, Saudi Arabia, and one Canadian expert in tall buildings says there are no real physical limitations when it comes to how high skyscrapers can scrape.
"Technically, we can pretty much do anything we want. It's just that if you were going to build a 20-kilometre tower, and it would take 100 years to build, it becomes unreasonable in terms of management and payback," says Richard Witt, a principal of Quadrangle Architects Ltd. and the chair of the Council on Tall Buildings and Urban Habitat's Canadian chapter.
While there have obviously been technological improvements that enable stronger, taller towers, Mr. Witt suggests that the only real magic ingredient is money.
"It's not something other than concrete or steel that's [needed]," he says. "There's not what we refer to as 'unobtanium.'"
That's not to say there aren't challenges. Simply carrying people up and down a kilometre-tall structure in a reasonable amount of time requires an unusual amount of internal infrastructure. The Kingdom Tower, for instance, will have 12 escalators and 59 elevators, some of which will be able to travel 10 metres per second.
The elements pose another obstacle to tall towers: Wind can sway the structures, sun on one side can cause them to curl. In addition, columns in high concrete buildings can shorten or shrink, something that must be taken into account ahead of time.
The Kingdom Tower is majority owned by one of Prince al-Waleed bin Talal's companies. The Saudi Arabian prince, who is known for courting attention and being outspoken in the media, also owns large stakes in two Toronto-based hotel companies, Four Seasons Hotels Inc. and Fairmont Hotels & Resorts Inc., and announced on his website last year that Four Seasons will be running the luxury hotel in the Kingdom Tower.
The tower is expected to cost in the neighbourhood of $1.2-billion (U.S.) to build. That's roughly the same amount that Toronto-based Dundee Real Estate Investment Trust paid to buy Scotia Plaza, the headquarters of Bank of Nova Scotia, in 2012.
So why doesn't Canada have a kilometre-tall tower? Because, so far, we don't have a billionaire investor who wants to gamble on a real estate project that could wind up being more about ego or legacy than stellar profits, given the potential for delays and cost overruns.
"We could build a kilometre-high tower here if we wanted," Mr. Witt says. "But Canada's a very cost-sensitive, conservative culture."
The wealth in this country tends to be tied up by pension funds and banks whose owners and stakeholders are looking for a high return on investment rather than the prestige of a trophy development, he adds.
David Scott, former chairman of the Council on Tall Buildings and Urban Habitat and a London-based lead engineer with Laing O'Rourke PLC, says in some cases, the benefits of super tall structures – such as the Petronas Towers in Kuala Lumpur, which stretch more than 450 metres high – come from the spinoff effects.
"I do think that for many countries it's about making a statement," he says. "So I think that it had an enormous effect in Malaysia and it helped to teach people that Malaysia can build some of the most sophisticated buildings in the world, and they are not a backwater country."
While Asia and the Middle East are at the forefront of tall towers, most of the consultants working on them are Western, Mr. Witt says.
"Five years ago, eight years ago, we were looking at a 1,500 metre tower," says Mr. Scott. But it didn't come to fruition. "The incremental change in height depends on the amount of money you have, and your commitment and time."
Riz Dhanji, vice-president of sales and marketing at developer Canderel, says it's tough enough to construct a 273-metre building. That's the height of Canderel's Aura at College Park condo project, which is close to completion in Toronto. The project is being billed as Canada's tallest condo, although there are already proposals for taller ones.
"It's a very complicated process," he says. "We incurred a lot of costs to be able to do this."
An example? "We had three hoists at one point that were going up. They started early in the morning, at 6 a.m., and one hoist would take workers up the building and then two hoists would be just the materials that go up. So you had the co-ordination of three hoists, where you'd usually use one in a building."
He also points out that it's been a six-to-seven-year project, which is longer than most condos take to build.
"Will we do it again? Who knows," Mr. Dhanji says. "But it's been an amazing ride."