Rooftop Speculations. Tokyo Rooftop Urbanism

Isometric diagram of rooftop spaces in Ueno-Okachimachi district in Tokyo

The notion of extensive rooftop usage is not new, even though, for some, it might seem quite exotic. From the very beginning (early twentieth century), when flat roofs have been widely introduced, visionary architects of the time imagined a city with its rooftops "crowned by roof gardens". Le Corbusier, the master-mind of the modernist movement, listed the roof garden as one of the five elements towards a new architecture. German landscape architect Harry Maasz predicted a metropolis where "man will stroll from roof garden to roof garden" (Werthmann 2007). This vision was not realized to its full extent, instead rooftops adapted to the local needs and acquired their roles respectively (more on this under ‘Eastern’ and ‘Western Perspective’ in Chapter 1).

As has been illustrated by the findings of this research, rooftops in Tokyo, per their usage frequency and typology, are probably somewhere in between the aforementioned 'Eastern' and 'Western' situation. They are not so extensively used, as to host many additional 'parasitic' settlements  as it happens in the Eastern context, nor are they the privilege of the few (as in the West), because they are much more accessible and, thus, facilitate different rooftop usages.

However, there is still a lot of non-utilized potential in the form of vast free space, (often) accessibility and unique spatial qualities. The following pages would attempt to speculate on the ways to appropriate and utilize rooftop space.
As the ground for such speculation, three areas from the Mapping section have been selected, namely Higashi Ueno, Tomigaya and Hongo. These three areas present with different spatial and functional character, which is favourable for differentiated rooftop interventions and, thus, more productive discussion.

Higashi Ueno is a densely built urban area with mostly regular grid. Being located next to the famous Ueno Park, major stations Ueno and Ueno-Okachimachi, the shopping district of Okachimachi, it is a fairly lively area. The buildings here are mostly high-rise, skinny office or residential towers, with occasional different functions being inserted in the ground floors (food, small shops, etc). The tight regular grid of the buildings only occasionally has small patches of greenery inserted into it. Overall, the area gives impression of being rather time-worn.

Per the results of Rooftop Mapping from Chapter 2 (p. 40), Higashi Ueno area indicated the highest rate of rooftop usage—with the highest categories being MEP utilities, custom (enclosed) structure, and gardening. The area has also shown the highest percentage of custom enclosed structures (in most cases, presumably, illegal structures) in comparison to the other areas, which goes along well with the layered and weathered character of  the area. Due to the heavy business-nature of the district as well as age of the buildings, the management of the area does not appear to be strict at all: most main doors of the buildings are open, there is no guard at the bottom and the staircase to the rooftop is usually not locked.

In response to such nature of the area—old office buildings and little to no open green space—a number of rooftop spaces have been appropriated to serve as recreational spaces for the offices underneath. The existing air conditioning equipment on the roofs, where possible, has been fenced off with lightweight wooden fences with aesthetic purposes. Greenery has been introduced in the form of bigger trees and smaller vegetation in planters. Some of the rooftops have been connected into a small network of recreational spaces with the help of multi-level metal structures with stairs.

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