Flat vs slope roof
It seems compelling to why mid eastern homes more commonly have square roofs while European houses have sloped roofs. The most obvious reason should be a drainage system. Sloped roofs can easily direct water outwards while in hot climates where rain is uncommon a flat roof with a slight inclination is sufficient. In cold climates a flat roof would be horrendous as ice could block drainage points leading to a built up and in the extreme case cause the roof to collapse because of the pressure. Water could sneak into the brickwork through leaks and cracks. When the water would turn to ice in the cold causing expansion between the 2 states the structure would slowly weaken.
Today flat roofs give modern homes a more abstract and simplistic look. Many offices, skyscrapers, apartments and malls adapt the flat roof for efficiency energy and space wise. The construction uses less material and is thus cheaper. As long as there is a membrane of asphalt, tar or bitumen to waterproof the roof, and it is frequently maintained a flat roof will go just fine.
Skyscrapers
Breaking fast in Dubai at the top of the Burj Khalifa is different than on the surface. Because of the angled view from high heights the sun may have already set on the surface while 1 kilometer up (828m) it has not. Thus the residents on the top floors must wait an extra 3 minutes. Architectural beasts such as the burj khalifa is the result of the world’s best innovative engineering to counter all odds and the forces of the earth.
Skyscrapers were born after the Chicago fire in 1871. Of course the fire was devastating lasting for the course of 3 days, like a natural coming forest fire that sets land for the new generation of trees, Chicago exploded with population. The only way to keep up with the demand for more housing was to build upwards. Steel framed buildings able to withstand fire and pressure soon came in.
The reason why towers like the Burj Khalifa, the empire state building or the hundreds of tall radio towers don’t topple over is because they possess a deep foundation beneath the surface to stabilize their center of gravity. If the ground is weak the other option is to make the foundation wider like that of the burj. It follows that of a bundled tube structure allowing for higher heights. In contrast to a rectangular block tower the burj is wide at the surface as the sides are cut off and thins as it gets higher. Winds at high heights can be volatile and the burj’s architecture is made to deflect it. The steel framework allows the building to sway as a whole if it does manage too.
Energy efficiency is also key for skyscrapers. The One World Trade Center newly finished just half a year ago uses ultra clear glass allowing sunlight to pass in with little resistance. This allows less use of energy on clear sunny days.
http://www.rockfordhomes.net/pros-cons-flat-roof/
https://en.wikipedia.org/wiki/Flat_roof
http://www.bbc.com/news/world-middle-east-14437334
http://www.discoverychannel.com.au/images/the-history-of-skyscrapers/
http://gurumagazine.org/askaguru/skyscrapers-fall-heavy-wind/
http://science.howstuffworks.com/engineering/structural/skyscraper4.htm
https://en.wikipedia.org/wiki/Tube_%28structure%29
http://www.infoplease.com/spot/skyscraperhistory.html
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