The way we build hasn’t really changed over time,
but now a revolution is sweeping construction.
Prefabrication, where parts of a structure are manufactured in a factory away from site
before being delivered for assembly, is starting to seriously take. off,
and for good reason.
Able to reduce cost, time, risk and waste, while improving safety,
quality and productivity - the benefits of offsite construction
are finally finding traction in a world that needs it more than ever.
But the technique is no longer limited to small scale projects.
From towering skyscrapers to vast airports, these huge projects
were all made in factories.
Prefabrication is not a new concept.
While its origins can be traced back even further,
prefab houses were being shipped to Australia as far back as the 1840s,
and the technique became a key part of the UK’s post-war recovery
in the mid-20th century.
Today, with our world facing new housing shortages,
offsite construction techniques are still most-used in homebuilding.
But with high-rise living now becoming more popular,
architects and engineers are taking prefab construction to new heights.
The 215-metre De Zalmhaven One residential tower in Rotterdam
is being built entirely from precast elements - at a rate of one floor a
week - and will become the world’s tallest prefabricated skyscraper when it completes.
The structure is the centrepiece of the De Zalmhaven project,
which includes two other 70-metre towers and comes at a time when
demand for living space and land prices are rising across the Netherlands’ main cities.
Its challenging site location, restricted space and tight schedule
mean that hundreds of facade, balcony and stairway parts,
as well as thousands of internal walls,
were all pre-manufactured before being delivered to site and hoisted into place.
Meanwhile in Singapore, these twin 56-storey prefabricated skyscrapers
are set to be built on the city’s western edge.
All 988 residential modular units that make up the Avenue South Residences
will be constructed in factories offsite, then assembled by crane one-by-one.
While prefabrication is usually optional, the local government sold the land on the
condition that offsite methods were used in any new development.
With prices averaging over a million US dollars, and with each tower offering
sky gardens and waterfront views, the project directly challenges the idea
that prefabricated buildings have to be unsophisticated or without style.
But offsite construction is by no means limited to housing
and the approach is now being used in several airport upgrades,
including Clark International in the Philippines.
A new passenger terminal nearing completion at the transport hub
in Pampanga features precast concrete floor slabs and wall elements throughout.
Its design is based on a modular concept,
enabling many components to be prefabricated.
This speeds up the build process, keeps costs down
and enables the terminal to be easily expanded in the future.
The main structure’s undulating roof is also made from
sustainably-sourced glued laminated timber - or glulam - imported from Austria,
with arches inspired by the nearby Mount Arayat.
Stadiums are also embracing offsite.
Now one of Europe’s leading sports venues, set to host matches at the
delayed Euro 2020 football tournament, the Puskás Arena in Budapest relied
on ready-made construction to achieve its challenging three-year build time.
Stairs, beams, grandstand and slab elements
were all manufactured away from the site,
while the stadium’s 38 monolithic support structures
were made from precast concrete reinforced with glass fibre
using bespoke polyurethane moulds weighing almost two tonnes.
Finished at the end of 2019, the 67,000-seat venue lies on the exact
same site as the historic Ferenc Puskás Stadium that it replaces.
Around 50,000 cubic metres of the non-precast concrete used on the arena
was recycled from the old ground,
and the new stadium also retains its predecessor’s eastern tower.
Away from buildings, prefabrication has been critical to the completion
of major bridge projects for many years.
The Öresund Bridge linking Denmark and Sweden
was the longest combined road and rail bridge in Europe for almost 20 years,
and remains one of the continent’s most iconic crossings.
Many of its components, including the huge caissons and piers,
had to be pre-manufactured on land, before being shipped out to the site for assembly.
But more recently, a 12-kilometre stretch
of the enormous Temburong Bridge in Brunei was constructed using
thousands of precast elements to limit damage to the rainforest.
China’s State Construction Engineering Corporation was tasked with building an
immense viaduct over a series of mangrove swamps, in unusually harsh conditions.
To minimise impact on the environment,
sections were manufactured off-site and craned into position.
In total, the viaduct features almost 2,000
prefabricated spans - more than any other bridge of its kind.
As our societies continue to adapt to the unprecedented changes
caused by the pandemic, prefabrication could soon become the ‘new normal’
and with the construction sector underpinning much of the global economy,
a greater offsite focus may be just what’s needed to build our way to recovery.
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