Rooftop Urbanism: Usage and Potential of Rooftop Space in the Urban Environment

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ROOFTOP URBANISM

Usage and Potential of Rooftop Space in the Urban Environment

Kawazoe Laboratory Department of Architecture Graduate School of Engineering The University of Tokyo

Veronika Smetanina

Primary Advisor: Yoshiyuki Kawazoe

川添 善行

2017-2018 5

I would like to express gratitude to everyone who has, directly or indirectly, contributed to this work: to my primary advisor Professor Kawazoe for his support and helpful critique, to my parents for their love and support, to Tyler McBeth for his continued encouragement, to Yoshiko Aoki, who was patiently guiding me through the survey data collected in Japanese, to Yuki Nieves for her knowledgeable translation of the project materials, to the Department of Engineering at the University of Tokyo for making this study possible, and, lastly, to all the kind people who enthusiastically participated in the research.

Veronika Smetanina

1 INTRODUCTION

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1.1 Perspective on Rooftop Space in Major Countries 1.1.1 Western Perspective

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Green Roofs, Rooftop Gardens and Penthouses The Potential of 'Rooftop Architecture' 1.1.2 Eastern Perspective

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Informal Rooftop Settlements 1.2 Tokyo's Urban Context

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1.2.1 Dense Urbanity 1.2.2 'Metabolizing Tokyo', 'Amoeba City'

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1.2.3 Tokyo's Townscape

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1.3 Tokyo's Roofscapes

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1.3.1 Nature of Tokyo's Roofscapes

2 MAPPING (Urban Scale Investigation) 2.1 Background Explorations

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Typology of Rooftop Space Usage (Tokyo) 2.2 Purpose

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2.3 Method 2.4 Results and Evaluation

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Higashi Ueno

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Azabu-Juban

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Tomigaya

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Shinsen

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Waseda

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HongĹ?

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2.5 Rooftop Mapping: Conclusion

3 CASE STUDIES (Architectural Scale Investigation)

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3.1 Objectives

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3.2 Format

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3.2.1 Dual Investigation 3.2.2 Questionnaire-Interview 3.3 Documentation and Findings

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Attached Deck

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Custom (Open) Structure

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Custom (Enclosed) Structure

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Gardening

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Net Cover + Prefab

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Laundry Cage

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3.4 Case Studies: Conclusion

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4 CONCLUSION

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5 ROOFTOP SPECULATIONS

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Higashi Ueno

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Tomigaya

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HongĹ?

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6 REFERENCES

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7 APPENDIX

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7.1 Documentation of the Rooftop Typologies (Photographs)

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INTRODUCTION Perspective on Rooftop Space in Major Countries Tokyo's Urban Context Tokyo's Roofscapes

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Introduction There is already more than enough mediocrity around, and there is no room for it on the roof.

(Ed Melet, Eric Vreedenburgh 'Rooftop Architecture')

Perspective on Rooftop Space in Major Countries

1.1

As architecture differs greatly in different parts of the world, so do rooftop spaces in response to the local climate, economic, and social needs. The only aspect, however, that stays common, and is shared between all the instances of rooftop spaces and rooftop architecture around the world, is the excitement that they evoke. As the authors of the 'Rooftop Architecture' book argue, it is the passion with which rooftop architecture is created that sets it apart, and there is no room for mediocrity on the roof (Melet and Vreedenburgh 2005).

What is going to be referred to here as 'Western' and 'Eastern' perspectives shall not be understood literally in terms of the geographic location, but rather as two major approaches to rooftop spaces that exist in the world to date. Western perspective refers here to the discussion on rooftop space conditions in such parts of the world as Europe and North America, where usage of the rooftop spaces and building on rooftops is not very common.

Eastern perspective relates to the countries and parts of the world where rooftop usage and building on the rooftops is quite familiar—Asia, Southern America, Africa.

Western Perspective

1.1.1

Green Roofs, Rooftop Gardens and Penthouses It may well be argued that for the most part the rooftop spaces and architecture in the West are regarded as something exclusive and privileged.

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The most immediate things that would likely come to mind upon hearing 'rooftop space' or 'rooftop architecture' in this context would be penthouses, rooftop gardens or green roofs—a quite natural image as those are the most commonly occurring instances of rooftop architecture in the given context.

Besides the mentioned exclusive examples of attractive rooftop spaces, the rest is often left unutilized or becomes a redundant space of no significant value that does not even require access and that can be used to host all the ungainly, unsightly technical utilities such as HVAC units, antennas, piping, wires, and so on. As the architect Joseph MacDonald has described this situation: "Today the roof is in the firm hands of the HVAC

guys" (Werthmann 2007). This is, Christian Werthmann argues, not at all how the flat rooftops that were introduced in vast number at the beginning of the twentieth century were envisioned by the prominent minds of the architectural world at the time—at that time the breakthrough technology that made construction of the flat roofs possible had been seen as an opportunity to create green roof oases at the top of the city (Werthmann 2007).

Perhaps, it is because of this very fact that rooftop usages occur so rarely in the West, that they have become very exclusive and chic. The high cost of any such intervention is usually regarded as the main reason of not implementing it as well.

The Potential of 'Rooftop Architecture' However underappreciated and underutilized roof spaces might be in the West, they have the potential to be extremely powerful and versatile spaces—this is argued by the authors of the book 'Rooftop Architecture', which is presented as 'a plea for rooftop construction' (Melet and Vreedenburgh 2005). According to them, cities in the West are very prone to the process of decentralization, where due to economic reasons certain functions are removed from the city centres, making them lose their layered character—"as

a result, almost every part of the city has assumed a uniform character: exclusively residential, exclusively for work..." (Melet and Vreedenburgh 2005). Rooftop architecture, thus, can be means to return cities their original 'layered' nature and bring new excitement into the stagnant environment.

Such decentralization, in return, brings a new set of economic and social issues to the cities, which have lost their diverse and layered nature, experienced a 'mass exodus' of residents to the outskirts, and the historical city centres has become nothing else but 'frozen in time' monuments. The phenomenon has been described by Guy Debord as 'Society of the Spectacle': "Everything that was once lived directly has now become nothing

more than a representation" (Debord 1967).

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Eastern Perspective

1.1.2

In the East, contrary to the West, the use of rooftop spaces and the appearance of rooftop architecture is very common. Rooftop extensions are especially well used, due to the economic necessity of the working class to live in close proximity to the city centres where most of the economic activity is taking place. An extensive research study on such informal settlements has been published in the book 'Metropolis NonFormal' which is raising an awareness about such settlements, which can also be known as 'slums', 'favelas' or 'shantytowns'. The authors of 'Metropolis NonFormal' argue for the necessity of designing for such places as the number of them is only going to grow, while the gap between middle class and those who are forced to live in poor conditions becomes only bigger (Werthmann and Bridger 2016). Right now, one billion people are living in informal settlements around the world (or one out of eight people), and this issue becomes even more crucial as the estimations predict that this number is expected to grow in the following years and reach 4 billion people living in informal settlements by 2050. (UN HABITAT 2015)

Informal Rooftop Settlements One of the most well known instances of informal rooftop settlements are the informal rooftop communities in Hong Kong, which have been extensively documented by Rufina Wu and Stefan Canhem in the book 'Portraits from Above'. These are unimaginable structures, often extending as far as three additional floors into the sky from the tops of the existing buildings. These structures are illegal and labelled by the government as 'unauthorized building works'. However, they often have fascinating layouts and use space ingeniously. Notably, they also have extremely poor living conditions as they are made from scrap materials. Some of them are merely sheds that will be completely flooded under rainfall. People still choose to live in such conditions because this is the only place to live that they can afford while allowing them to stay in close geographical proximity to their jobs in the center of Hong Kong. They choose to live in these conditions, so they do not have to travel many hours every day on the train to the living districts of the city, which besides taking up to four hours a day can also cost a considerable amount of money. However, residents of these extreme dwellings often speak quite fondly of their rooftop spaces (Wu and Canhem 2010).

This example illustrates how in exceptional cases rooftops can become new ground to build a solution for the entire community and provide an opportunity for less fortunate residents to find cheap housing within the megalopolis.

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Tokyo's Urban Context

1.2

The urban context of Tokyo, which is the basis of this research, stands apart from both Western and Eastern urban conditions. It is very common to attribute the unique feature of Japan (Japanese culture, architecture, townscape) to the fact that it is an island country that for a long time has existed in isolation from the rest of the world, and this lead to the cultivation of its many unique features. Even though this might hold true for some of the many unique cultural aspects, it does not provide a comprehensive explanation for the complexity of unique features in the Japanese built environment.

In regard to such analysis Professor Yoshinobu Ashihara goes back to the roots of historical development of architecture in Japan and observes the strong influence it has experienced from the local climate. Ashihara reasons that it is the unique climate of Japan (with hot humid summers and cold dry winters) that has had the deciding influence on shaping the traditional architecture of Japan in a unique way away from the rest of the world. He also argues that, contrary to the fact that Japan was heavily influenced by China throughout history, and in opposition to the common believe that Japan and China have a lot in common in their architectural and urban approaches, he states that China has more in common with the West than Japan (Ashihara 1989). Thus, Japanese architecture and townscapes are once again set apart from the rest of the world and are seen to possess very unique qualities that result in unique urban phenomena.

Dense Urbanity

1.2.1

One of the well-known qualities of Japanese and, especially, Tokyo’s urban context is its extreme density. As of 2018 with the estimation to 2020 Tokyo Metropolitan area is still world’s most populous metropolitan area and one of the most densely populated urban areas ("City Mayors: World's Largest Urban Areas In 2020" 2018). This often results in very ingenious and compact architecture—at times as narrow as 1.9 m. This phenomenon has been given the name 'Pet Architecture' in a book of the same name

by Tokyo Institute of Technology Tsukamoto Architectural Laboratory and Atelier Bow-Wow that documents multiple instances of miniature 'pet architecture' that finds its own way to adapt to the cramped conditions of the 'small Tokyo'.1 'Small Tokyo' refers to the book of the same name by Darko Radović and Davisi Boontharm.

In the introduction by Paul Waley Tokyo is described as a 'small' city—"despite its vast size Tokyo appears strikingly small" with its small houses, narrow streets and cramped conditions.

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'Metabolizing Tokyo', 'Amoeba City'

1.2.2

Another well-known and very distinct quality of Tokyo’s urban fabric is its dynamic character. This is represented by the extremely short average lifespan of buildings in the city—only 26 years according to Yoshiharu Tsukamoto (Kitayama, Tsukamoto and Nishizawa 2010), who is a prolific contemporary architect and urban researcher and who is one of the authors of the aforementioned 'Pet Architecture'. This does not encourage a sentimental relationship with the brick and mortar of one’s house as it is common in the West, but rather allows architecture to be viewed as a thing of transient nature. "Japanese are accustomed to thinking of architecture

as temporary"—states Yoshinobu Ashihara (Ashihara 1989). What is valued and preserved in Japan is not the stones of which architecture is made, but the knowledge that had been used to create it. This is demonstrated by the old Japanese tradition of rebuilding Ise Shrine every 20 years in order to preserve the building technique and replaced the weathered timber with the new one (Fruneaux, Gardner and Berg 2015). This is a fundamental difference in the philosophy of perceiving one's built environment which has greatly influenced the fast 'metabolising' nature of Japanese urban context.

Yoshinobu Ashihara also points out the 'Amoeba city' quality of Tokyo, calling it 'a perfect example of the fluid, regenerating city'. It possesses an inherent ‘parts-to-the-whole’, or bottom-up approach to the urban development—buildings, districts and highways emerge where there is a 18

Fig. 1 ↖ ↑ Tokyo's 'mountainous' urbanscape

need, without much planning or consideration of the bigger picture. If such interventions cause any trouble, counter-measures are taken to resolve them after the fact. All is in the process of constant flux and change, constantly adjusting to the ever-changing conditions of the environment. "Whether

the amoeba city is good or bad, it does persevere" (Ashihara 1989).

Tokyo's Townscape

1.2.3

A discussion of the Tokyo’s roofscapes would be impossible in isolation, without a preceding understanding of the nature of the urban context. As has been illustrated before, Tokyo is a unique environment undergoing constant change and with little control over the resulting whole. This naturally results in a somewhat chaotic (at the first glance) urbanscape.

While it might appear chaotic, it is being governed by a set of processes and rules, that are not immediately apparent (something that Yoshinobu Ashihara calls 'the hidden order').

This chaotic appearance takes it roots from the irregularly developed city network, which has all kinds of misshapen lots of land. Owners of those lots would most often wish to exploit them to their fullest potential by building on the site up to its limits. Upon these initially irregular outlines a set of building laws is imposed, which even among the chaos are highly concerned with light access to the city. The result is even more irregular geometrical modifications derived from a need to provide sunlight access 19

to certain areas (Ashihara 1989).

Tokyo's Roofscapes Nature of Tokyo's Roofscapes

1.3 1.3.1

Tokyo’s Roofscapes are an integral part of the city townscape and thus inherit the very same chaotic appearance—with their sloped roofs, differentiated height and irregular outlines it almost resembles something with a natural, rather than a man-made, character. The overall effect is further amplified by its mountainous relief, with drastic drops and peaks, creating a landscape of artificial mountains and valleys (Fig. 1).

The nature of the roofscapes is then the one that can be expected from the ‘Amoeba City’—it is ever changing and adaptive to the needs of that time. Rooftops in such city can serve almost anything, even as a circulation path to an adjacent structure (see Fig. 2).

Tokyo’s Roofscapes are also unique from the viewpoint of the West because of the rooftops accessibility. In the West a proper entrance to the rooftop is rarely designed, as the rooftop is not supposed to be accessed and used. A technical entrance might be present, but it would not be adequate for everyday access. In Tokyo however, exterior staircases of buildings go all the way up from the street level and connect to the rooftop. These staircases often serve as the main vertical circulation, making rooftop access very easy.

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Fig. 2 ↖ ↑ Otsunakotohira Shrine in Yokohama connected with a metal bridge to the adjacent building's rooftop which serves as the main circulation means because the other access to the shrine (on the photo—bridge on the right) requires going up the high hill

Fig. 3 ↑ ↗ Attached metal decks that most often are being added to the buildings as an afterthought

Tokyo’s roofscapes can indicate signs of the 'metabolizing' nature of the city as well and provide a ground for adaptation processes. A well-known Japanese architectural movement, Metabolism, that was very influential during 1960s - 1970s acquired its name from natural processes of the body.

This name was used to convey the idea of an adaptable architecture, that can, just like a life form, 'grow', 'shrink' or change in other flexible ways in response to the immediate needs of the city. The metabolist movement is commonly considered a utopian or a 'failed' movement, however, it seems that the idea of adaptability itself remains inherent to the ubiquitous town architecture in Tokyo. If a need in additional space arises, a building extension 'grows' on top or to the side of an existing building. A common instance of such adaptation can be observed in a form of ubiquitous attached decks in the city. They reside on roofs of the existing buildings, adapting even to complex geometries of pitched roofs (see Fig. 3). The following chapters in this research seek to investigate different rooftop space uses that occur in Tokyo and the forms they take.

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MAPPING Background Explorations Typology of Rooftop Space Usage (Tokyo) Purpose Method Results and Evaluation Conclusion

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Mapping (Urban Scale Investigation) Background Explorations

2.1

As a preliminary urban exploration for this research, numerous urban field trips have been undertaken to get acquainted with and study the urban context. To be more precise, the inspiration and original ideas for this research project were devised during these explorative trips, thus the two are inseparable parts of the same process of recognizing the phenomena of the diverse uses of rooftop spaces in Tokyo.

Typology of Rooftop Space Usage (Tokyo) Rooftop (Space Usage) Typology has been devised based on the numerous observations and extensive documentation carried out during the urban explorations in Tokyo. The most commonly recurring rooftop uses have been recognized and documented, upon which it has become possible to devise this new typology. It serves as the basis for the rooftop mapping.

Before introducing the Typology of Rooftop Space Usage in Tokyo, it is necessary to outline the limitations of this typology, which are as follows: / the typology is based on the Tokyo context, and thus is unique to Tokyo and must be evaluated within the Tokyo context / the typology is simplified for the purpose of this research, rooftop categorization and data analysis, therefore there might exist exceptional cases which are not covered by this typology / the typology categories are based simultaneously on the functional uses of the rooftop spaces as well as their physical expression (e.g. attached deck, net cover or a prefab). This has been done due to the two reasons: first—the physical expressions in most cases is inseparably connected to the use of the rooftop space (i.e. the attached deck is mostly used either for laundry, gardening or both), the net cover is used for the practice of various sports or to protect rooftop items from the strong winds). Secondly—due to the scale of the rooftop mapping it would be extremely challenging (if not impossible in certain cases) to determine the exact functional use of the rooftop space simply by observation (e.g. for such typology as prefab, it is impossible to determine the functional usage for each instance without direct communication with the owners/users).

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Typology of Rooftop Space Usage consists of several groups (categories) with several sub-categories within, namely:

/ no utilization /no utilization (pitched) - the roof is pitched, or the upper part of the building is highly sloped, thus not leaving much of usable rooftop space, which is relatively common occurrence in Tokyo due to the building regulations in connection to sunlight access (see Fig. 4) / no utilization (no entry) - here is no comm access or entry to the rooftop (vertical ladders on the sides of the building for the mechanical equipment access are not considered as such) / no utilization - the rooftop has a satisfactory access and Fig. 4 ↑ Diagram explaining slopes of the upper parts of buildings intended to provide sunlight access (Yoshimura, 2006)

50 or more percent of the rooftop area is unoccupied space

/ technical utilization /advertisement banners - in this case large advertisement billboards occupy most of the rooftop space (50 or more percent of the rooftop area) /solar panels - the rooftop surface hosts solar panels /MEP equipment - the rooftop space is occupied by any kind of mechanical/electrical or plumbing equipment (i.e. air conditioner units, antennas, water tanks, etc.)—50 or more percent of the rooftop area /green roof - some kind of vegetation layer in present. Its purpose is to cool down the rooftop surface, and thus, improve the environmental condition and the heat island effect (not to be confused with gardening or rooftop gardens, green roofs mainly serves the goal of environmental improvement, and do not require high maintenance, and thus, usually there is no access to the roof). / public use* - any kind of a public facility located on a rooftop (e.g. rooftop gardens and walkways, sport fields, amusement parks, etc.)

/ mixed (private) usage /attached deck - usually metal (steel), attached on top of a roof (often serves as a solution for pitched roofs) /custom (open) structure - any kind of open structures (e.g. pergola, shade pavilion structures) /custom (enclosed) structure - any kind of enclosed structures made of custom materials, with a custom design (i.e. not a prefabricated structure) /gardening - individual efforts by residents to grow miscel*public use typology is the only typology that is not represented on the Fig. 5 due to its vast, all-encompassing character

laneous types of plants/trees/flowers/vegetables, etc. /net cover - net cover attached/mounted on the rooftop 27

(usually for protection from strong winds and/or to prevent objects falling from the roof); used for a variety of functions, most often leisure (i.e. golf/ basketball practice space, planting for protection from strong winds, archery ranges) /prefab - prefabricated (enclosed) volumes /laundry cages - metal "cage-like" structures placed on top of buildings for the purpose of drying laundry See Appendix—Documentation of the Rooftop Typologies for the photographic documentation of each typology under Mixed (Private) Usage Category.

Purpose

2.2

The goal of the urban rooftop mapping was to perform an in-depth study of the character of rooftop uses and their ratios, in a context of different urban areas as single entities. Based on the results—to make a comparative analysis of the rooftop space usage ratio in different areas of the city in order to determine if it is possible to establish relationships between the rooftop usage ratio and the character of the corresponding city area, and to uncover the underlying forces that encourage particular rooftop space uses on the larger urban scale.

Six areas of the city have been selected for the mapping and analysis based on the background urban explorations of the city. The main criteria for the selection was significant presence of rooftop structures which are listed under ‘Mixed (Private) Usage’—the ones most commonly referring to an individual effort of inhabitants to appropriate and make use of available rooftop space. These typologies represent the main interest and focus of the this research and are studied in-depth in the following Case Studies.

Method

2.3

The main parameter of evaluation that is being determined by mapping is the ratio of how frequently each of the typology occurs in any given area—i.e.

Occurrence. (See Fig.) It is calculated in the following way:

( Total number of buildings ) 100 Number of buildings

where Number of buildings stands for the number of buildings in which a given typology occurs within the study area.

In addition to this, another parameter that is being calculated for each of the areas is the BCR (Building Coverage Ratio) which is calculated in the following way:

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(

Building Footprint Total Area Site Total Area

) 100

BCR calculation is intended to indicate how densely built each of the areas are and to help determine if there is a direct correlation between density of the built environment and the ratio of rooftop uses.

In order to determine a comparable rooftop usage ratio in the selected study areas, the size of each area was initially established as the same—an equivalent of a 220 by 220 m, which corresponds to the area of 48,400 m2. However, due to the fact that each area has a peculiar urban layout, street pattern and building distribution and in order to preserve each of the area's integrity, (where possible) complete city blocks have been taken into account and these have determined the outline of the study areas.

This resulted in a fluctuation of the overall site areas between around 44,000 and 55,000 m2. This, however, will not undermine the quality of the comparative analysis, as the resulting ratio used from these areas are still comparative: the ratio for each area is based on its own data set, which would change correspondingly in accordance to the change in the area's square meters (i.e. if the area's outline is bigger, it includes more buildings, the total number of buildings and their footprint increase—the parameters based on which the ratio is calculated).

Rooftop Mapping has been performed for the following areas in Tokyo: Higashi Ueno, Waseda, Hongō, Tomigaya, Shinsen, and Azabu-Juban. The following pages present the mapping diagrams as well as the calculated ratio and BCR results for each of the areas.

The mapping is based on the building footprints obtained from openstreetmap.org, which have also been used for the calculation of Building Footprint Total Area. The mapping has mostly been informed by direct observation of the mapping sites from an elevated point. Where the direct observation was not possible, aerial footage of Google Maps and Apple Maps have been consulted. The order in which the resulting mapping visuals are presented is based on the results of the ratio evaluation—the areas with the similar resulting rooftop usage ratio are presented together in one section, starting from the areas with the biggest rooftop usage ratio: Higashi Ueno and Azabu-Juban, to the Tomigaya-Shinsen group, and, finally, Waseda and Hongō.

Fig. 5 ↓ (next page) Rooftop (Space Usage) Typologies

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TECHNICAL UTILIZATION

NO UTILIZATION

Typology of Rooftop Space Usage

not utilized (pitched)

not utilized (no entry)

not utilized

advertisement banners

solar panels

MEP equipment (air conditioners, watertanks, etc.)

green roof

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custom (open) structure

custom (enclosed) structure

MIXED (PRIVATE) USAGE

attached deck

gardening

net cover

prefab

laundry cages

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HIGASHI UENO

AZABU-JUBAN

TOMIGAYA

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SHINSEN

WASEDA

HONGO

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Results and Evaluation

2.4

Rooftop Mapping of the presented areas has helped to reveal a number of important findings. Perhaps, the most important one is that it has allowed to establish a connection between the resulting rooftop usage ratio results and urban character of the areas: paring of the areas based on the ratio results (from the biggest to the smallest) has proved to be the same as when the areas were grouped by other characteristics such as layout, prevailing function, sectional character. (See aerial photographs of the areas on p. 32-35).

The mapping has also helped to determine that there might not necessarily be a direct correlation between the BCR (i.e. the built density of the area) and the rooftop usage ratio, as the result for Hongō area indicated the highest BCR—53%, while showing one of the lowest overall rooftop usage ratios (only 15%) (Fig. 6).

In addition to this, the rooftop mapping has also helped to find out distinct local peculiarities of each of the areas by indicating when a higher percentage of certain typologies occurs in one particular area. Thus, for example, Higashi Ueno presented the highest percentage of the occurrence of Custom (Enclosed) Structures (See Fig. 7, red index color), which corresponds to the somewhat chaotic urban character of the area—it is a dense regular urban grid with no 'injections' of vegetation, a lot of functions are layered on top of one another, the area has a strong and constant traffic of people coming from small businesses, and of tourists from the adjacent Ueno area. The whole area seems like it has "given up control" over its rooftop spaces and therefore has all kinds of additional structures emerging on top of the existing buildings.

On the opposite side from this is the most "proper" area of those investigated—Tomigaya, which is almost exclusively a prestigious and wealthy residential area in close proximity to Yoyogi Park, Shibuya Station and Komaba Campus of the Tokyo University. This area has showed the highest ratio of the green roof occurrence (6.2%, see Fig. 7, light green index color) , which is, as mentioned previously, a conscious effort to improve the environmental situation. There are no instances of such typologies as Custom (Open) or (Enclosed) Structures, Prefabs or Net Covers on the roof, which means that residents of this area most probably do not have such an immediate need to expand upon the rooftop space, and even if they did the regulations and management of the buildings in the area would prohibit such expansion.

Such areas as Shinsen indicated the highest percentage of rooftop usage for the purpose of installing advertisement banners, which are naturally located along the area outline adjacent to the major highway (see the mapping diagram for Shinsen on p. 39 and the aerial footage on p. 34).

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Fig. 6 ↑ Spreadsheet of the Rooftop Mapping Data

Fig. 7 ← Resulting pie-charts of the Rooftop Mapping 47

Rooftop Mapping: Conclusion

2.5

Performing the rooftop mapping on the selected urban areas in Tokyo helped to correct the preliminary assumptions and to draw important conclusions on the local peculiarities of each area.

It has proved that it is not only the density of the urban area that impacts the character of the rooftops usage, but a more complex set of factors that determine the unique urban character of an area, and thus, encourages corresponding rooftop uses as well.

Perhaps most importantly, these results have illustrated that rooftop mapping proves to be as effective as traditional functional mapping for drawing conclusions about local character of the areas. By taking into account only this one dimension of an urban unit—the rooftop level—it enables us to draw conclusions about local features of each area, and in certain cases even helps to reveal the forces that are active within that urban entity. It Is these forces which impact the shape that the buildings and their rooftops take.

Thus, rooftop mapping can be used as a method for the background research of the areas for potential urban interventions at the rooftop level.

The method that has been presented here should only be considered as a starting point in rooftop investigation and analysis. More detailed investigations, such as including rooftop area calculations, and performing a traditional functional mapping and buildings height mapping would be immensely helpful in informing the rooftop space investigation and enable to derive a more precise conclusion about the forces that are shaping it.

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CASE STUDIES Objectives Format Documentation and Findings Conclusion

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Case Studies (Architectural Scale Investigation) Objectives

3.1

Case Studies focus on the rooftop typologies that have been devised during the background explorations of Tokyo’s urban context and are referred to as 'Mixed (Private) Usage' under the Rooftop Typology (see Fig. 5 on p. 3031). Mixed (Private) Usage typology most commonly implies an individual effort to use/appropriate rooftop space—a phenomena which represents the main interest of this research. The goal of Case Studies is to study in detail each of the typologies under Mixed (Private) Usage category and learn first-hand facts and experiences that can only be obtained from users and owners of those private rooftop spaces. Case Studies also aim to confirm or correct assumptions that were developed from the "outside", i.e. based on preliminary observation and analysis.

Among the important details that are expected to be revealed through the process of Case Studies, the most essential one is understanding the viewpoint of those who use the rooftop spaces frequently on the main benefit of such spaces. Thus, some of the preliminary assumptions about such viewpoints are going to be evaluated through the Case Studies. Presumptions include: / people recognize the unique spatial qualities of the rooftop spaces (the feeling of vast openness, the isolation from the noisy street level, the aesthetic urban panoramas, etc.) and are prone to exploit their potential; / people recognize the underutilized potential of free space on the roofs and want to make use of it from a pragmatic point of view; / people regard rooftop space as an opportunity to engage in activities which otherwise they have no suitable place for; / people recognize rooftop space as a business attraction; / people wish to utilize the natural qualities of the rooftop space as an open space—sunlight, wind, fresh air; / people wish to engage into social interaction by means of rooftop space; / people wish to find solitude and tranquillity in the rooftop isolation

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Format Dual Investigation

3.2 3.2.1

Urban Case Study Format is represented by a detailed study of one exemplary case from each typology. Each case study is comprised of two parts—"outside" and "inside" analysis, which complement each other. The first part, the outside analysis, is based on observation and careful visual documentation—detailed diagrammatic representation of the building/ structure, analysis of its function, elements and materials. The second part, the inside analysis, is the data collected from first hand users—owners, creators of the rooftop spaces and structures via questionnaires. Such a dual character of the investigation makes each case study well informed and ensures its comprehensive quality.

Questionnaire-Interview Format

3.2.2

The questionnaires are very detailed and contain many important open questions, which makes them much more like written interviews in their nature (see Fig. 48, p.74-79). The written form of the interview was selected with considerations for the language barrier, in order to precisely record the data, as well as provide the interviewees with sufficient time to contemplate answers to the questions (in most cases, the interviews were left for a week with the interviewees). In addition, occasional important facts were revealed in the conversation with the interviewees, which is also presented in the textual narrative form.

The questionnaire format and contents were greatly inspired by the questionnaire presented in the thesis 'Building a Community Rooftop Network: Design Prototypes for Taipei' by Chen Hai, University of Washington, 2014.

Documentation and Findings

3.3

The following pages present the complete record of the six Case Studies that cover all the seven typologies under Mixed (Private) Usage category: Attached Deck, Custom (Open) Structure, Custom (Enclosed) Structure, Gardening, Net Cover+Prefab, Laundry Cage. Net Cover and Prefab are the two typologies which are covered under the same Case Study. Buildings for each of the Case Studies were selected based on their unique interesting character and, what is more crucial, owing to the kind enthusiasm of the rooftop users and owners to participate in the research.

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Case Study - Attached Deck The building picked for the Attached Deck typology case study has a particularly interesting story behind the development of its environment as well as the reasons to expand onto the rooftop space. The building is a two-story residential timber structure house built in ~1962-1963. It is a Japanese timber structure with some traditional elements like a pitched tiled roof. It appears, however, that at the time of construction the environment around the building was drastically different.

As was found through the questionnaire and verbal interview with the owner of the house, the big elevated highway which nowadays stretches in front of the house at the level of the house's rooftop did not exist at the time of the house construction. It appeared shortly after the house has been finished, as one of the instances of major infrastructure expansion before the 1964 Tokyo Summer Olympics. This fact can be seen in old maps of the area, which show the difference between the layout of the area—the

Fig. 8 ↑ 1944-1954yy, Komaba, Shibuya-ku (ktgis.net 2018)

map of 1944-1954 does not have the highway or any other major roads around the house (Fig. 8). Whereas the map of 1965-1968 clearly shows the new elevated highway road and the widened road perpendicular to it which "cuts" through the district that previously had a net of narrow roads and streets that were not even close to the scale of the new elevated road (Fig. 9).

As if to further worsen the surrounding situation for the house, it has also unfortunately been facing the wall of an adjacent building. This new tall mansion (multi-story apartment building) was built behind the house in 2011 (suumo.jp 2018). It is an eight-story building which appears to be considerably out of scale in relation to the surrounding buildings inside the same city block (primarily, 2-3 story detached residential houses except for the taller mansion buildings at its corners) (see Fig. 13).

The metal deck was attached to the house's rooftop 15 years later than the houses original construction. It was meant to serve as a laundry

Fig. 9 ↑ 965-1968yy, Komaba, Shibuya-ku (ktgis.net 2018)

drying space and it cost 50,000 yen to install (approximately 500 US dollars).

The deck structure appears to be a very typical metal structure (similar to those from the Attached Deck typology found around Tokyo). However, it has a small additional second level serving as a threshold from the house's second level onto the slightly sloped eaves of the roof above the entrance, from which a set of stairs leads to the deck itself.

Still, however cramped the rooftop conditions are, the owner of the house is speaking quite fondly of the rooftop space. He sees it as having the feeling of openness—the quality which has been progressively lost over the years due to the urban development around the house.

Fig. 10 ↑ Google Maps (Google, 2018)

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corrugated opaque plastic - to isolate from the tall residential building behind

two-level metal deck structure access to the structure

corrugated opaque plastic - to serve as railing

Fig. ↑ 11 Case Study 1 - Attached Deck

Fig. 12 ↑ Case Study 1 - Urban Context

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Fig. 13 ↑ Case Study 1 - Architectural Context

Fig. 14 ↑ Case Study - Attached Deck

One of the issues in connection to the rooftop deck that has been mentioned by the owner- is that it becomes troublesome to use in strong wind (which occurs fairly often in Japan, especially at the change of seasons). There is no barrier or protective net/surface on the sides of the structure, so in case of strong winds the drying laundry is in danger of being blown off the deck.

Another concern that the owner has with the structure is its weight. Japan has extremely high seismic activity, where small earthquakes can occur on almost a weekly/monthly basis, and a stronger earthquake is expected in the near future (Mogi, 2004). Consequently, the house owner is worried about the excessive weight of the metal deck structure in relation to the timber structure of the house, which can cause great damage at the time of a big earthquake. Therefore, among the things that the owner would like to improve about his deck, he is primarily concerned with having a more lightweight structure.

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Case Study - Custom (Open) Structure Sakura Kitchen Cafe is a recently opened cafe with a rooftop terrace near Komagome St., Tokyo. Finished in 2017, it is a new building, located within only 3-5-minute walk from the station. It overlooks the tracks and frequently passing trains of JR Yamanote Line (Fig.15). Interviewee was the 60 years old owner of the cafe who also works there as a chef.

According to the owner, the cafe was designed and built with the purpose of making use of the quality of "openness" that is present at the site—the main facade of the cafe faces an open space above the railway tracks, there are no buildings at the immediate borders to the cafe (as is common in the densely built Tokyo), and no buildings are blocking the views to all four sides

Fig. 15 ↑ View from the rooftop terrace onto the train tracks

(see Fig. 19).

The building is timber post-and-beam structure, with the custom open structure on the rooftop made from timber as well. The structure on the roof is a typical pergola structure intended to provide shade and support the vines that are starting to develop along it (Fig. 16). The rest of the elements on the rooftop are made from timber as well—the decking, an elevated podium under the pergola, tables and chairs, garbage disposal and tray return stand.

Interestingly, even though not mentioned in the questionnaire, during the talk following the questionnaire collection, the owner mentioned that the Japanese, unlike Westerners, do not like having meals outside because of the miscellaneous external factors that bring discomfort—heat/cold, wind, insects, etc. Indeed, one can notice how drastically fewer places with the terraces for eating outside there are in Tokyo in comparison to European cities, except for the fashionable cafés and restaurants that are purposefully designed with a reference to European style.

Nonetheless, the cafe and the rooftop terrace seem to be quite popular—at the time of collecting the questionnaire (the time span between around 3 to 5 pm on a weekday), the cafe proved to get its fair share of customers, who enjoyed their drinks/meal and the afternoon sun on the rooftop terrace overlooking the passing by trains.

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Fig. 16 ↑ Timber pergola structure on the roof

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pergola structure for supporting vines and creating shade outdoor seating area for the cafe facing railway tracks

Fig. 17 ↑ Case Study 2 - Custom (Open) Structure

Fig. 18 ↑ Case Study 2 - Urban Context

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Fig. 19 ↑ Case Study 2 - Architectural Context

Fig. 20 ↑ Case Study - Custom (Open) Structure

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Case Study - Custom (Enclosed) Structure The building is a 4-story timber structure, which serves as a restaurant (on floors 2-4). The construction year is unknown.

One of the peculiar features and, also apparently one of the main attractions of the restaurant, is the semi-enclosed structure on its roof.

The top floor of the building does not occupy the whole footprint, but is rather recessed, and houses a staircase that connects the top level to the floors beneath, while leaving portion as a completely open space. It is in this place where the custom veranda has been placed to provide outdoor seating for the restaurant. The veranda itself has two distinct elements— the seating area covered with a roof and enclosed on three sides, and a separate metal structure with a pitched roof in front of the seating area.

Fig. 21 ↑ Google Street View

The latter structure previously served as the mount for a large paper lan-

Footage, Nov 2009 (Google,

tern (Google Maps Street View footage of Nov 2009). The paper lantern

2018)

used to carry the kanji (Chinese characters) for the restaurant name on it and, apparently, served as the main attraction element for the restaurant.

However, nowadays the lantern itself is no longer there (Fig. 27) and the reasons for that are unknown, as the employee of the restaurant who has been interviewed did not know about the lantern's existence.

However, the rooftop structure still functions as a veranda for outdoor seating for the restaurant. The structure is steel frame with the usage of prefabricated steel profiles, tension cables and bolt connections. The wooden planks are used on the sides of the structure and on the floor, which is elevated from the rooftop level on concrete blocks (see Fig. 23). The side of the structure that is adjacent to the tall building is completely covered in

Fig. 22 ↑ Google Earth Imagery of June, 2010 (Google, 2018)

wooden planks, while the opposite side which is more open—only partially covered in planks. The other part is covered in a curtain which can be pulled back and make the space more open. The same operable logic is applied for the roof of the structure - it is a tarp on a system of strings that allows the ceiling to be opened when desired and exposed to the sky.

The main point of potential future development expressed by the interviewee was making the surfaces of the rooftop structure easier to clean. As an employee of the restaurant, he is concerned with keeping the outdoor restaurant area clean, which according to him is quite labor intensive right now.

Fig. 23 ↑ Structure Base Details

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coated fabric on an operable system of strings that allows veranda space to be opened on demand steel structure that used to serve as a mount for a big paper lantern

Fig. 24 ↑ Case Study 3 - Custom (Enclosed) Structure

Fig. 25 ↑ Case Study 3 - Urban Context

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Fig. 26 ↑ Case Study 3 - Architectural Context

Fig. 27 ↑ Case Study - Custom (Enclosed) Structure

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Case Study - Gardening Using the rooftop space for gardening is one of the most common usages of rooftop space in Tokyo—it is simple, effective and very enjoyable. With the distinction previously made under typology classification, what is referred to here as "gardening" is the individual efforts of inhabitants on their private property, rather than governmentally/publicly/business funded rooftop projects. The residents of the building in this case study are an elderly couple who own a detached 3 story house. The house was built in 1973, and they started using the rooftop 23 years after the construction. It is mostly the husband's effort—a man of age 66—in growing vegetables and flowers.

The setup on the rooftop is very simple—it is mostly pots and planters slightly elevated from the rooftop surface by the means of wooden planks or rubber mats. The only additional element that has been added to the rooftop in regards to the gardening usage is the greenhouse-like tent of polyethylene fabric (Fig. 28). The tent is used as a storage space for gardening tools which are preferred to be kept out of the rain, as well as pieces of small foldable

Fig. 28 ↑ Lightweight polyethylene tent for the storage miscellaneous items and tools

furniture. The tent, being a very lightweight structure, would be very easy to get blown away in the case of even mildly strong winds. To prevent that, the tent is simply tied with a string on it's upper four corners to the railing on the rooftop.

Interestingly, the rooftop adjacent to the one in this case study has extensive gardening taking place as well. The interviewee and his wife were mentioning some facts about it and the owner too, speaking of what they (the owner) grow and how they are setting up the table for outdoor meals from time to time. This fact proves that rooftop spaces (mostly, the ones that are of relatively similar elevation and close proximity) serve as a very active communication ground between neighbours, and probably, much more so than the street. This is a unique quality of rooftop spaces that can provide opportunities for facilitating communication between neighbours, which is extremely important especially for the elderly population in Japan where the problem of aging population has been ongoing for decades and percent of the elderly population living alone is continuing to grow (Statistics Bureau, Ministry of Internal Affairs and Communications 2016).

Among the interesting facts revealed through the questionnaire was that the owner was aware of the heat island effect and was considering rooftop gardening as the main benefit of rooftop spaces that can have a positive effect on the improvement of environmental condition.

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Fig. 29 ↑ View to the neighbouring rooftop with gardening

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vegetables gardening covered with protective net

greenhouse-like tent made out of polyethylene fabric

Fig. 30 ↑ Case Study 4 - Gardening

Fig. 31 ↑ Case Study 4 - Urban Context

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Fig. 32 ↑ Case Study 4 - Architectural Context

Fig. 33 ↑ Case Study - Gardening

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Case Study - Net Cover + Prefab This case study combines two typologies simultaneously—a net cover and a prefab. As observed during multiple urban explorations, net covers of such kind often serve as a DIY solution for some kind of practice—baseball, basketball, football, archery, etc. In this case study, too, the net cover proved to serve as a small golf practice field—it is meant to prevent the golf ball from flying off the rooftop (Fig. 34).

The prefab structure in this case serves as a storage space—for the golf equipment as well as miscellaneous household items that are not in use at the moment (e.g. summer futon (traditional Japanese style of bedding) (Fig. 35).

Usually, prefab structures like the one here are additions to the building

Fig. 34 ↑ Golf practice set-up with a net cover

which have been made after its completion. Often, they are structurally, material- and finish-wise drastically different from the building they sit above.

However, this is different in the case, where according to the interviewee—a resident of the 4th floor of the building—the structure has been placed on top of the building since the very beginning (28 years ago), and it has been in use by the interviewee since then. Interestingly, this is contrary to the conclusion one might devise from simply observing the structure and the rooftop. A logical assumption would be that the structure had been added after the building completion as it bears no structural connection to the rest of the building—an impression reinforced by the fact that additional steps made out of chequered steel plate were placed to access the rooftop, which,

Fig. 35 ↑ Inside the prefab structure

perhaps, was not planned to be frequently accessed (Fig. 36).

Among the benefits of using the rooftop space the interviewee mentioned the fact that the rooftop space can be used at any time without having to go out of the building. This is a very strong point for rooftop spaces, because the Japanese who live in such urban conditions do not typically have a satisfactory open private space in their dwellings (in case of mansion residences)—space such as balconies or verandas, if present at all, are typically quite small, mostly used for practical purposes such as laundry drying. Occasionally people would grow plants on their balconies, but even those are often required to be lower than the railing height to preserve the homogeneity of urban facade. Smokers cannot use the balconies either as it is usually prohibited to smoke there.

All these factors are not encouraging the use of the balconies as a private leisure space, and it is certainly very rare (unlike in the West) to see people in Tokyo spending long time on their balconies or verandas, using the space for anything other than taking care of the laundry/plants or stepping outside only for a moment to check the weather. This is where rooftop spaces can provide a great opportunity to have a private or a semi-private open space for any activities for which there is otherwise no room for.

Fig. 36 ↑ Additional steps leading to the rooftop

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net cover serves as a golf practice field and contains stray hits

prefab structure is used as storage for golf equipment and other household items

Fig. 37 ↑ Case Study 5 - Net Cover + Prefab

Fig. 38 ↑ Case Study 5 - Urban Context

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Fig. 39 ↑ Case Study 5 - Architectural Context

Fig. 40 ↑ Case Study - Net Cover + Prefab

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Case Study - Laundry Cage The building is a 7-story reinforced concrete multifamily residential building.

It was built in 1972, and interviewee for this case study was a resident of the 4th floor of the building, who has lived there since the very beginning.

The building has metal structure on the roof for laundry drying, which at the first glance appears to have been attached later on, however according to the resident and the building manager (who happened to be there at the time of the interview), the structure was designed together with the building and meant to be used for drying laundry.

Strangely however, most apartments in the building have balconies and some people are using them for laundry too, but some people are actively using the space on the rooftop also. In regard to this, the building manager mentioned that it is mostly old buildings that have laundry drying space on the roof–the newer ones are trying to integrate the drying poles on balconies (only below the railing, due to the regulations that are active in many districts in Tokyo, which prohibit drying laundry in an exposed way—i.e. above the balcony railing). However, even though the newer buildings are integrating drying poles or even electrical dryers inside bathrooms, the building manager admits that she personally likes the old, rooftop system much better, because it feels so much nicer to go out on the roof. This comment is very important as it corresponds to the main idea of this pro-

Fig. 41 ↑ Case Study - Laundry Cage

ject—to utilize the potential of rooftop spaces which provide unique feelings of openness, being elevated above the hustle of the streets, and having breathtaking views. The rooftop of this case study has amazing potential even based solely on the skyline that it opens to—from the building's rooftop a panorama of almost 360 degrees is available, one can see the buildings of Shibuya and Shinjuku, landmarks such as Tokyo Tower and the Sky Tree (see Fig. 42). This is an amazing asset in the dense city of Tokyo, where it is very common for one's window to face the wall of another building.

At the time of the interview and photographic documentation, which was Saturday afternoon, at least 5 people went up on the rooftop to put out or collect the laundry, or for the mother to take her daughter up onto the roof to play. If just a portion of the roof, surrounded by metal poles and a net brings so many people to the top of building, one can only imagine how much the building community would benefit from a very basic re-design of the rooftop space—better decking, more seating spots, some plants, a small shaded area for elders, and perhaps a small playground for kids.

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Fig. 42 ↑ Case Study - Laundry Cage - Panorama from the rooftop

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metal safety railing separating the passageway to the laundry cage and to the EV shaft access

metal “cage” structure to protect laundry from being blown away in strong winds and ensure safety laundry drying poles

Fig. 43 ↑ Case Study 6 - Laundry Cage

Fig. 44 ↑ Case Study 6 - Urban Context

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Fig. 45 ↑ Case Study 6 - Architectural Context

Fig. 46 ↑ Case Study - Laundry Cage

Fig. 47 ↓ Spreadsheet with the questionnaire answers

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Case Studies: Conclusion

3.4

Information obtained from the questionnaires and verbal interviews with owners and users of the rooftop spaces, as well as the extensive observation and documentation of the cases has helped to confirm the expected results and assumptions about the users' perspective in regard to the rooftop spaces.

It has also helped to gain a deeper understanding of the issues and limitations concerning the rooftop space usage from the perspective of its users/creators.

Thus, four out of six interviewees named the spatial and natural qualities of rooftop spaces (a pleasant feeling of openness, fresh air, sunlight) as their main benefits and all of them agreed that, where possible, people should be utilizing rooftop space potential as much as possible. The same reasonable drawbacks of such spaces have been recognized by all the respondents as well—the difficulties concerning natural events, such as rain, strong wind, or snow, as well as the troublesome maintenance of rooftop spaces as the consequence.

Case Studies investigations, and in particular the interviews, have also revealed some important points which would not been possible to have found out otherwise. Thus, the Attached Deck Case Study illustrated the influence of the urban growth and development on the individual residential space and how the cramped conditions caused by the urban expansion make it a necessity to expand upon the rooftop space to accommodate the basic domestic needs. The same Case Study also revealed the present problem and concern about the structural safety of such expansions—an attached deck structure (commonly made from steel) has a considerable weight, which might be the cause of serious damage in the case of a strong earthquake (an omnipresent threat in the Japanese context). This issue needs to be addressed as there is a big number of such structures residing on dilapidated houses, especially in recognition of the fact that these structures, most probably, have been installed without a proper structural evaluation of the host house.

The two Case Studies of the cafe, and a restaurant with a rooftop terrace (Custom (Open) and Custom (Enclosed) Structures) have confirmed the assumption that rooftop spaces and their unique qualities are recognized as an important asset by business owners and efforts are made to design for those spaces in order to attract customers.

The Gardening Case Study has proved that among other benefits of the rooftop spaces, they have the unique ability to serve as a unique communication ground between neighbours (the same concept as the one behind the design of the Gazebo House by the architect Riken Yamamoto). This quality can be exploited to address the problem of the elderly population living alone in Japan. As of the most recent population census of 2015, the percentage of population aged 65 and over is 26.7% in Japan, which is the highest in the world. Among the elderly group, the percentage of those living by themselves has also increased, indicating that "one out of 8 males

and one out of 5 females were living alone" (Statistics Bureau, Ministry of Internal Affairs and Communications 2016). This often causes the situation 84

when many elderly people live in isolation, experiencing an extreme lack of communication with their families and friends. In answer to this issue, rooftop spaces can be a ground for interventions aimed at encouraging the communication between neighbours, creating space for the local community interaction and engagement in common activities such as gardening, sports and other hobbies.

The Net Cover+Prefab Case Study has illustrated a perfect example of using the rooftop space as an opportunity to create a private open space to engage in the practice of favourite sport activities, only a few steps away from one's doorway.

Lastly, the utterly utilitarian laundry drying structure on top of a multi-family apartment block creates a constant traffic of the residents up and down the rooftop, thus creating an opportunity and space to meet and communicate with neighbours. This arguably outdated and troublesome way to manage the daily need is admittedly much more pleasant as it provides a dose of fresh air, sunlight and beautiful views each time there is a need to dry laundry.

These examples illustrate only a partial range of unique opportunities that exist in the form of rooftop spaces in the urban environment and many more are yet to be explored and exploited.

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Conclusion Rooftop Dimension The research efforts in this work have helped to further explore a (yet) not so well studied and familiar urban dimension—the rooftop dimension. It has helped to reveal certain relationships between the character of different urban areas and the corresponding roofscape. Hopefully, it has helped to shed more light on the processes that are happening on the rooftop level in a peculiar urban environment such as Tokyo and would raise more interest in studying such emerging phenomena in other different local contexts.

Informing Urban Interventions The methods presented in this research (area-specific rooftop usage mapping, and detailed observation- and survey-based case studies) can be applied as a starting methodology in the urban roofscape investigation. They should be further developed and refined to include other types of data, and it could serve as a solid basis for informing a future urban intervention.

Potential to Be Exploited Rooftops in the urban environment present a great potential, an asset that can be exploited endlessly. It is a vast free space in the context of extreme density and cramped conditions. It is access to the fundamental natural resources, such as sunlight in the environment where the usual street level of human existence has become submerged in the shadow of the concrete skyscrapers and can barely receive a portion of sunlight even on perfectly clear days. It is an opportunity to find places to engage in one’s favourite sports and hobbies in one's own private open space, in the conditions where all the other space is occupied and has a strictly defined purpose, often with a long list of prohibitions. It is an asset to be utilized for the business owners for giving a unique spatial quality to their enterprises. It is an opportunity to engage in communication with your neighbours which would probably not happen otherwise—in the dark corridors and hallways of apartment blocks.

The potential of rooftop spaces is truly endless and should be exploited to bring new dimension and excitement into the habitual environment.

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Rooftop Speculations 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.

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HIGASHI UENO 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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TOMIGAYA Tomigaya is a wealthy, prestigious, and peaceful residential neighborhood in close proximity to such central areas as Shibuya and Yoyogi Koen, as well as Komaba Campus of the University of Tokyo. It is a mix of detached private houses, middle-rise apartment complexes, and few high-rise apartment blocks. It has many small tasteful stores and coffee-shops. Based on the results of Mapping from the Chapter 2, this area has showed the biggest percentage of green roofs (a positive environmental initiative) as well as a big percentage of roofs being used for laundry-drying structures. The building from the 'Laundry Cage' Case Study (p. 74) is also located within the area.

The process of acquiring the interview has shown that the rooftop with the laundry structure is being extensively used, serves as a meeting ground for the residents, and even as an open 'playground' for kids.

A number of similar in nature interventions have been devised for this area based on its residential and family character. The rooftop with the laundry structure has been redesigned in order to free up more space, to accommodate other functions such as actual playground structures for kids, a small baseball training area, shaded areas for outdoor seating and meetings of the elderly, small areas for gardening. Another rooftop of a big mansion has accommodated a bigger soccer training field. The smaller rooftops have been presented with private outdoor areas.

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HONGO Hongō is an old area of Tokyo, that is mostly regarded as an educational area, since it serves as a home for the main campus of Tokyo University, Juntendo University, and Toyo Gakuen University. The block selected for the speculative design proposals is heterogeneous residential area with mostly low-rise buildings—one to three or four stories high. Overall, Hongō was the area that presented with the lowest rooftop usage ratio due to the presence of numerous one-two story high buildings with pitched roofs.

Among the prevailing usages were gardening, attached decks, solar panels and MEP equipment. Based on the direct observation during the field trips, the area seems to have many elderly residents as well as students living in close proximity to the University of Tokyo.

Given the character of the area, few rooftop interventions have been introduced to try and address its needs. Thus, some of the rooftops acquired lightweight, temporary workshop places for students and enthusiasts.

Some of the pitched roof were presented with small tea-house structures of the same logic as the attached metal decks. Other accessible flat roofs could have community gardens—to give (among others) elderly residents the opportunity to engage in communication with their neighbors, and to create more green spaces in the densely built urban block. Lastly, the rooftops that have available free space, but do not have an entry, could become green roofs—by having a thin layer of vegetation, they could help to cool down the roof surface, and reduce (even incrementally) the urban heat island effect. There is no need of an entry to green roofs, as they do not require high maintenance.

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APPENDIX Documentation of the Rooftop Typologies (Photographs)

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attached deck

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custom (open) structure

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custom (enclosed) structure

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gardening

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laundry 'cages'

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net cover

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prefab

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Typeface: Lato, Abel, Orator © 2018 Department of Architecture Graduate School of Engineering The University of Tokyo Kawazoe Laboratory S202 4 - 6 - 1 Komaba Meguro - ku Tokyo 〒 153 - 8505 Japan

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