The scale and ambition of skyscrapers lead
many of us to view them as permanent fixtures on our city skylines – but for all their size
and presence, these huge structures are in fact just as replaceable as anything else
we build. So what do you do with buildings this big
when they reach the end of their lives? How do you demolish them in the middle of such
heavily developed and densely populated areas? To date, only a handful of towers taller than
150 metres have ever been intentionally destroyed. The process is highly complex, specialist
and fraught with challenges. In a world that is constructing more tall
buildings than ever before and with several structures now slated for demolition to make
way for even larger towers, this is how to dispose of a skyscraper. Skyscrapers are a highly effective way of
creating space in dense city centres – but with life-spans ranging from 50-100 years,
many no longer provide the right type of space needed in a modern metropolis. Now, an increasing number of tall buildings
around the world are being earmarked for demolition, clearing the way for even larger developments. In New York City, the 216-metre 270 Park Avenue
recently became the tallest skyscraper ever to be intentionally demolished, making way
for JPMorgan Chase’s new 70 storey structure. When we think about the demolition of a building, many of us imagine wrecking balls and dramatic implosions. But while these methods may be the quickest
way to destroy large structures – like stadiums or casinos – their use within built-up, heavily
populated areas is challenging; and the effects of noise, dust, citizen safety and proximity
to other built assets prohibits their use. Rather than coming down in a matter of seconds, the removal of a skyscraper is in fact a carefully planned process that is carried out piece-by-piece,
much like the construction of the building, but in reverse. It’s perhaps easier to think of the process
as “deconstruction” rather than “demolition”. While skyscraper disposal can take a few different
forms, the primary method sees contractors and engineers start from the top of a structure
and work down. Once the relevant demolition plans and permits
are approved, contractors must first contain and remove any harmful materials or substances
– such as asbestos – to avoid contaminating the surrounding area. With internal strip-out works underway, the
building becomes enclosed in scaffolding and netting to minimise the impact of noise, dust
and debris on the public and neighbouring properties. While this can take the form of a complete
enclosure – like that which went up around Sydney’s 188-metre AMP Tower during its
partial demolition in 2019 – the sheer scale of 270 Park Avenue sees the disposal process
broken-up into four phases. Levels 16, 29 and 41 of the structure have
been stripped-out and modified into bracing floors, supporting the scaffolding for each
section of the tower above. As each section is fully enclosed, internal
fixtures, services, and eventually the building’s windows are removed – leaving only the concrete
and steel superstructure remaining. This process is repeated for each section of the tower. The method of moving waste material from the
top of the building down to street level varies between disposal projects, but contractors
tend to use chutes and hoists for non-structural waste, minimising the time that cranes are
needed on site. With windows and cladding removed and the
tower stripped to its core superstructure, small excavators and handheld tools are used
to break-up the concrete floor slabs and steel framing. This process is steadily repeated level-by-level
until the skyscraper is no more. Though there are alternatives to this method
– such as this “creative demolition” in Japan, where all work is contained within
a hydraulic framework – the principles remain much the same. While tearing down an entire skyscraper could
be seen as wasteful, it’s important to note that landfill costs account for a large proportion
of a demolition contract. As such, every effort is made to reduce the
amount of waste that is sent to landfill by recycling and reusing waste material as far
as possible. To date, 270 Park Avenue has reportedly diverted
over 90% of its waste away from landfill, putting it well ahead of LEED’s highest
standards set for demolition projects. The cost and effort required to fully dispose
of skyscraper makes it a significant undertaking – and the process is seen as a last resort
amongst developers. Though more skyscrapers are set to be demolished
as urban populations expand, building adaptation is becoming an increasingly attractive alternative
to demolition. This process sees skyscrapers significantly
altered for new uses while still retaining the bulk of their superstructures. New York City’s Woolworth Building had its
upper floors converted to luxury residential apartments when the tower’s structure prevented
it from offering the open-plan offices that large companies required. While in Sydney, the redundant AMP Tower will
retain over 60% of its original structure as it is transformed into Quay Quarter Tower,
a 216-metre sustainable skyscraper. If you enjoyed this video and would like to
get more from the definitive video channel for construction, subscribe to The B1M.