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.
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