Matt Stephenson is a Principal and architect at Woods Bagot with a prominent 15-year career that has featured the adaptive reuse of several structures, including significant projects such as Gramercy Square, 49 Chambers, and The Buchanan. His work extends to nationally recognised discussions, such as the ‘Breathing New Life into Old Bones’ duologues hosted by the Urban Land Institute (ULI) and the Council on Tall Buildings and Urban Habitat (CTBUH), where he has championed the economic and environmental benefits of revitalising existing building structures.

Unlocking the deep floorplate is complex, but not impossible.

Adaptive reuse is undoubtedly key to ensuring the stable, sustainable future of our built environment. However, while some adaptive reuse opportunities lend themselves to a smooth transition of purpose, the path for others is harder – such is the case with the deep floorplate.

Dark, cavernous and habitually less articulated than their smaller, typically older counterparts, the deep floorplate became more prevalent after 1960 when advancements in building systems and technologies allowed floorplates to expand. Now between 30 and 70 years old, these buildings make up a large percentage of the office building stock in our cities – much of which has been left empty with the rise of remote work.

Despite the challenges they pose, deep floorplates can, and must, be repurposed. When we consider the prevalence of these buildings through the lens of the social and economic implications of leaving them empty, this makes significant design and financial sense.  

The conversion of a deep floorplate often requires the consideration of significant envelope modifications, changes to the building massing, and the necessity for a mix of uses – all of which come with their own set of approvals. Overall, the deep floorplate requires new approaches that unlock the building’s floorplate to consider future use.

Related: 7 stories on adaptive reuse

Dependent on variables like location and laws, we can approach this to add value in several ways:

The Perimeter: This approach is what’s been most typical when larger floorplates are converted to residential. It involves placing units, normally around 30 feet deep, around the building’s edge to create a border of standard-size residences that have access to natural light in all habitable rooms. The main issue with The Perimeter is that it leaves a large, central area of the floorplate unused and without access to light and air, leaving a frustratingly dark space that lacks a purpose and generates no potential for additional rental or sales income.

The Slim-fit: Some jurisdictions allow the incorporation of leaner, longer units that extend into the depths of the darker floorplate – creating space for more units and, by extension, more revenue potential. The approach solves The Perimeter’s problem of unused space and allows for more apartments to fit on a floorplate, but it does leave spaces in each apartment without direct access to light and air. While smart design and programming can go a long way towards resolving this challenge, it is important to note as a potential challenge to designing livable spaces.

The Atrium: This approach involves cutting the dark, harder to repurpose part of the existing structure out of the building center to create an atrium: an inner cavity that allows light to reach into the building’s core. To avoid the loss of building area, the removed area can be repositioned as an ‘overbuild’ on top of the building, if the existing structure allows. While this method is the most direct in solving the challenge of access to light, interior structural removal is costly and zoning regulations may not allow for the addition of floors at the top of the building to recognise all floor area that’s been removed, creating an unappealing premise to underbuild in some of the world’s most expensive cities.

The Lightwell: A similar approach to The Atrium, The Lightwell in some cases allows a smaller cavity – a lightwell – to be cut through the building’s dark core to create light and air for interior-facing units. This approach allows natural light into all units but does sacrifice some of the outward-facing views typical of most buildings. However, The Lightwell does make room for efficient, interior-facing units, which may appeal to investors.  

The Inset: Adding exterior loggias and pushing the facade of the building in at the large base of an existing building to create more outdoor space allows for normalised unit depths. In this example, outdoor areas could be included in unit sales costs where an interior core area typically cannot. In most cases, office building facades will need to be reclad to allow for operable windows – so shifting the location may be an incremental cost.

The Storage Core: The Storage Core approach is one that would allow the center of the building to be used as a secondary building typology – like third-party storage or a data center – allowing for minimum adjustment to existing floorplates as well as additional opportunity for revenue. To allow for each use type to function independently, existing office core vertical transportation and egress could be maintained. This supplemental revenue stream and reduced construction cost could help unlock more conversions.

Adaptive reuse supports a practice of ongoing care – for history, the built environment, the natural environment and the future. While the deep floorplate comes with its own set of challenges, approaches like The Perimeter, Slim-fit, Atrium, Lightwell, Inset and Storage Core demonstrate how architects can reposition, reprogram and redesign these underutilised spaces to better fit future needs.

Ultimately, to embrace adaptive reuse is to adopt a different way of viewing the world – accepting that a second (or third, or fourth) life does not mean second best.

Woods Bagot
woodsbagot.com

Photography
Courtesy of Woods Bagot

AHMM’s Paul Monaghan on setting up in Sydney and an expertise in retrofitting