Architecture on the Roof

ARCHITECTURE ON THE ROOF An exploration into rooftop architecture and its potential applications within Portsmouth as a case study for UK cities.

ALEX PAUL

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AUTHOR’S DECLARATION

Title: Architecture on the Roof: An exploration into rooftop architecture and its potential applications within Portsmouth as a case study for UK cities.

Author: Alexander Richard Paul (UP645689) Word Count: 8695 The thesis is submitted for Unit 421: Thesis Dissertation in partial fulfilment of the requirements for the award of the degree of Master of Architecture at the University of Portsmouth. / I confirm that this thesis presented for the Masters degree in Architecture, has; i) been composed entirely by myself ii) been solely the result of my own work iii) not been submitted for any other degree or professional qualification

January 2018

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ABSTRACT

Developing on top of existing buildings has fascinated me from the minute I worked on my first airspace development, above a block of flats in London on my years’ experience before undertaking my Masters in Architecture. From struggling to find explicit planning policy to working closely with structural engineers, I was intrigued with the unknown surrounding rooftop developments and their potential application within UK cities, especially Portsmouth where I have completed my studies in Architecture.

This thesis forms an integral part of my second year studies towards my Masters in Architecture, providing the framework for my thesis design project. The research explored throughout this thesis has provided me with the opportunity to explore in greater depth the theoretical approaches of reappraising roofs through an analysis of built examples whilst challenging my application of innovative materials and building techniques to enhance and enrich my design proposal.

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ACKNOWLEDGEMENTS

This thesis would not have been possible without the support and help of many individuals and I would like to extend my sincere gratitude to them all.

I would first like to thank Catherine Teeling, my thesis dissertation tutor, whose expertise, understanding and guidance has made this possible and I have thoroughly enjoyed our discussions surrounding the topic. My thanks also go to Martin Andrews for his comments which enabled me to develop and refine my writing.

I am highly indebted to Gemma, my partner, for her endless proofreading and believing in me throughout my writing. I would also like to thank my family and colleagues who have provided me with support and guidance. You have all encouraged me and helped me focus on what has been a hugely rewarding and enriching process.

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CONTENTS

AUTHOR’S DECLARATION ABSTRACT ACKNOWLEDGEMENTS LIST OF ILLUSTRATIONS

ii iii iv vi

INTRODUCTION

1

0 // CONTEXT

0.1 HISTORY

0.2 PRESENT DAY

3 3 7

1 // ROOFTOP PRINCIPLES

1.1 PARASITIC VS SYMBIOTIC

1.2 TOPPING UP VS NEW FUNCTION

1.3 MATCHING VS CONTRASTING

1.4 TEMPORARY VS PERMANENT

11 12 14 15 16

2 // APPLICATIONS

2.1 RESIDENTIAL

2.2 SOCIAL

2.3 ENVIRONMENTAL

17 19 25 29

3 // CONSTRAINTS

3.1 STRUCTURE

3.2 ACCESS & FIRE SAFETY

3.3 PLANNING

31 32 33 34

4 // CASE STUDY: PORTSMOUTH

4.1 CONTEXT

4.2 METHODOLOGY

4.3 RESULTS

35 35 35 37

CONCLUSION

41

REFERENCES SOURCE OF ILLUSTRATIONS BIBLIOGRAPHY

43 47 48

APPENDIX A APPENDIX B

49 50

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LIST OF ILLUSTRATIONS

Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15

Fig. 16 Fig. 17 Fig. 18 Fig. 19 Fig. 20 Fig. 21

Fig. 22 Fig. 23 Fig. 24 Fig. 25 Fig. 26 Fig. 27

Fig. 28

Fig. 29 Fig. 30 Fig. 31

Ariel View of Commercial Road, Portsmouth Rooftop of Unite D’Habitation by Le Corbusier Timeline showing progression of Rooftop Architecture Skyscraper City - Seielstad Haus-Rucker New York Concept (1971) Hong Kong rooftop communities Airspace sold above site in New York for adjacent development Falkestrasse Office Extension, Vienna Parasite - Paris (Stephan Malka Architects) Diagram showing difference between Topping Up and New Function Images of proposed addition to Aldwych House by Sheppard Robson Pop up restaurant in Milan, Italy De Urbaniste’s concept image of the potential of Rotterdams rooftops Erection of Lotcube module on top of Hotel Daniel, Austria Perspective showing proposed impact of rooftop development at 190-196 City Road, London Tesco Streatham with airspace development of 250 new homes Elevations of Didden Village, Rotterdam Image of Didden Village, Rotterdam Image of Kinderstad, Amsterdam Various images of Rotterdam’s Rooftop Festival Aerial images of London (top) and Stuttgart (bottom) highlighting green roofs Lufa Farms Rooftop Farm in Montreal, Canada Hearst Tower, NYC by Norman Foster Rotterdam’s Temporary Scaffolding Staircase PUP Architects’ Service Duct addition Total flat roofs with potential for rooftop development Flat roofs with potential for rooftop development where residential use has been established Flat roofs with potential for rooftop development owned by Portsmouth City Council Before and After @ Doyle Court, London Road Portsmouth School with potential rooftop developments highlighted PUP Architects’ Service Duct addition

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INTRODUCTION

There is a lot of discussion and concerns about how we sustain our cities for both now and the future. How we do this is a major question to be answered by architects, designers, planners and city councils alike. Have we evaluated the city in a way to understand our needs to sustain our future? How do we resolve lost spaces, empty or simply left over spaces? Do we even consider these an important component for the development of our urban environments?

When viewed from above, cities offer little architectural inspiration – an urban landscape of dull grey roofs. The varying heights of buildings provides topography to this city landscape, creating unexplored latent voids of varying characteristics.

We as a profession often refer to the roof plane as the fifth elevation, but do very little with it, a lack of consideration and action on our part. Through habitation, the rooftops of tall buildings have the potential to offer expansive city views whilst lower rooftops have a connection to the already inhabited ground floor plane.

By the year 2025, it is estimated that 65% of the world’s population will be living in cities (Barley & Ireson, 2000). Thus space in the city is at a premium and architects and designers alike are seeking new solutions to resolve urban problems. For cities to become sustainable - environmentally, economically and socially - innovative ideas need to be explored, encouraging change in the lifestyles of city dwellers.

In dense cities, rooftops provide an uninhabited and often unresolved landscape, capable of becoming ‘the foundation of a new layer’ (Melet and Vreedenburgh, 2005, p. 10) providing an elevated platform for change to occur. These spaces offer a plethora of opportunities, from homes to social activity, integrating into the existing urban realm of cities.

Through investigating and analysing the potential of the unresolved roofscape, this thesis aims to explore the current typologies of rooftop architecture, both realised and theoretical, and the potential applications of these within UK cities.

They will be explored and evaluated to discover their potential and limitations to provide a balanced case, before applying the knowledge to the city of Portsmouth to understand the opportunities that the rooftop can offer, creating a framework for urban growth.

Fig. 1 - Ariel View of Commercial Road, Portsmouth

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CONTEXT

Fig. 2 - Rooftop of Unite D’Habitation by Le Corbusier

0.1 HISTORY In Western cities, many rooftops have been converted into affluent bars and penthouses, ‘far above the din and smells of the city’ (Melet & Vreedenburgh, 2005, p. 7). This was not always the case - in the 19th Century rooftops were once a place for the servants to be stowed away, far from the lavish lifestyles of their masters.

Whilst servants once inhabited the roofs, the rooftop soon became the domain for inventive decorative detail, showcasing the wealth and power of the residents (Busch, 1991).This remained the case until the advancements of the lift – allowing inhabitants to ascend rapidly to an elevated position, bringing a new luxury lifestyle that encapsulates city views.

Maximising the potential of a rooftop is not a new ideology, in 1923, within Le Corbusier’s ‘Five Points of Architecture’, the idea of the roof garden was a fundamental principle in the design process. The concept was based upon the premise that the roof garden should restore the area of ground floor covered by the house (Corbusier, 1986) hinting at the possibility that the roof can become more than its primitive function of shelter. Le Corbusier showcased his ideas, through completed buildings and concepts, that rooftops can support activities, gardens and social interaction, exemplified in Unite D’Habitation (Fig. 2).

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Worldwide

UK Context 1765 Airspace Rights Legislation Early 19th C

First Commercial Public Lifts

1914-1918

World War I

19th C

Servants hidden in rooftops

1923

Le Corbusier - 5 Points of Architecture

1935

Green Belt Legislation

1939

1939-1945

Skyscraper City - Seielstad

World War II

1957

Urban Rooftop Playground

1958

Yona Friedmann - La Ville Spatile

1970s

Haus Rucker

1987

Brundtland Report

1991

Akiko Busch - The Art of Going Through the Roof (Book)

2001

Majora Carter sets up Sustainable South Bronx in New York

2003

First LoftCube placed on rooftop Hotel Daniel, Austria

2005

Melet & Vreendenburg - Rooftop Architecture (Book)

2011

Lufa Farms’ first rooftop agriculture farm

FEB 2016

Consultation on upward extensions in London

AUG 2016

Consultation on upward extensions in London

Apex Airspace Report on London’s potential for rooftop housing

NOV 2016

Tesco begin discussions with developers to sell airspace

February 2016 Department for Communities and Local Government and Mayor of London

Fig. 3 - Timeline showing progression of Rooftop Architecture

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Whilst Le Corbusier focused on the integration of the roof plane into the design process, rooftops were beginning to be re-appraised on existing buildings across the world. Yona Friedman’s La Ville Spatiale looked at the benefits of inhabiting the elevated space as a place to live and work, with large fixed structures that allowed for flexible pods to be attached. Friedman’s work could be seen as a response to legislation protecting green space around cities coming to fruition, but also as a reaction to the need for the re planning of cities after WW2. His ideas allowed for the intensification of cities when required, ideas further developed within Rem Koolhaas’ Generic City in 1995.

Since 1935 UK planning legislation has protected the green belt surrounding cities, controlling urban growth and preventing unplanned sprawl. This constraint of many cities has led to important development and consideration of underutilised spaces and buildings within them. Exploiting these spaces, allows the city to grow vertically, layering buildings with new uses that further activates existing buildings to create unique experiences, specific to the demands of the city. Lucenti and Zamperini state that reclaiming the rooftop ‘does not aim at bringing existing parts of the city back to the original conditions of virgin soil, but to provide new spaces for planning’ (2014).

Fig. 4 - Skyscraper City - Seielstad

In the UK, designers were exploring more creative approaches, looking at the potential of placing sports facilities, schools and airports on a new elevated landscape (Fig. 4). These radical images show the exploration process of architecture dealing with relevant city issues of the time on a large scale. Whilst not at the intended scale of the original concept, recent examples have shown roofs capable of supporting activities like sports facilities and schools.

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Fig. 5 - Haus-Rucker New York Concept (1971)

Similarly in 1970’s America, Haus-Rucker, explored the possibility of urban rooftop development in New York, providing opportunities of large scale design solutions.

These concepts of the 20th Century vary drastically to the work that is being undertaken in the 21st Century, such as Majora Carter who is focusing more on community based applications, looking at the individual building scale. His work (Fig. 5) explored a fantastical approach, often being described as being ‘connected more to space that it is to the street’ (Busch, 1991, p. 16).

The design of the built environment then changed drastically and post war flat roof developments sprung up across the UK in the mid-20th Century. The exclusion of habitation continued with access typically being limited to maintenance staff, preventing residents and the public access, rendering these spaces wasted.

In the late 20th Century, Busch believed that rooftop development was sparse, disagreeing with comments of the time labelling the rooftop zone as the ‘second city in the sky’ and instead stating that it ‘remains a village rather than a city’ (1991, p. 21). Melet and Vreedenburgh reinforced Busch’s comments in 2005, describing rooftop development as so incidental and scattered among different cities that we can’t truly measure the benefit. The fourteen years between Busch, Melet and Vreedenburgh’s comments, suggests minimal progression in rooftop architecture.

Since 2005, there has been very little movement in utilising rooftops as a means for urban renewal, possibly due to the planning system and restrictive procedures and processes.

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0.2 PRESENT DAY In Hong Kong today and many other cities, the poorest communities inhabit the roof plane, creating illegal neighbourhoods rising above the city below. Building on the flat roofs of city centre tower blocks allows inhabitants to dwell close to the heart of the city with improved work opportunities. Typically, these settlements are built using the existing parapet wall to anchor the dwelling adding a further one to two storeys. The informal dwellings work collectively as a unit, much like the residents who inhabit the spaces, and structural stability is provided through ‘the additions of small ladders… uniting the roofs to form one continuous plane’ (Wu & Canham, 2009, p. 43).

Whilst Hong Kong culturally differs vastly to UK cities, the habitation of the rooftop can be seen as an example of natural and unregulated growth of the city. Melet and Vreedenburgh suggest that it is unlikely that the roof will be used in this way in the West, due to the cultural differences and the ways in which we inhabit our cities (2005). The rooftop communities are more akin to the favelas and slums seen across the world, only differing due to their location on the roof but nevertheless still serving the poorest communities within cities.

Typically in UK cities roofs have programmatic uses such as plant rooms, lift overruns and ductwork – providing access for maintenance. Allowing rooftops to be occupied by mechanical services, restricts public habitation and the potential for another alternative and innovative solution.

Fig. 6 - Hong Kong rooftop communities

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The re-use of rooftops is possible within the current planning legislation. Whilst not explicitly expressed, one of the core principles promotes the ‘effective use of previously developed land’, defining and encouraging planning as a ‘creative exercise in finding ways to enhance and improve the places in which people live their lives’. (National Planning Policy Framework, 2012). Similarly, Barley and Ireson agree that we need to look for different spaces within the city to revitalise it. Rogers and Burgett refer to these as ‘simply leftover spaces’ which need to be utilised in more sustainable ways (2001).

Melet and Vreedenburgh argue that the conventionally layered city has been decaying for the past hundred years due to cities being split into mutually exclusive zones, and as a result, these segregated districts are only used for a part of the day with little cross fertilisation between the functions (2005). This stance, whilst relatable to many cities, isn’t applicable to all, as many have undergone transformations to integrate uses. In London, a shift was made for zones to support more varied facilities to improve around the clock functionality of the city.

This layered approach to cities, unlocks potential at different elevations – allowing for growth. Barley and Ireson discuss the distinction of these levels and the varying spatial qualities they provide. Arguing that demolishing unsuccessful or ineffective neighbourhoods isn’t realistic ‘while leaving it to its own devices and allowing redundant parts die, is not an option.’ (2005, p. 20) By developing a city on multiple layers, Melet and Vreedenburgh believe that new life can be brought into stagnant neighbourhoods, regenerating cities without the need for demolition.

These levels have the potential to provide and support varying types of interaction, with new methods of access providing links between the different planes of the city.

As seen in other cities, this activity can occur but there is an understanding that this involves a change in mind set due to differing cultures.

Barley and Ireson argue that rooftop development by itself only heightens the divorce of high-level territory from life on the streets (2000). In contrast, Melet, Vreedenburgh and others disagree, arguing an intervention on the roof can act as a catalyst for improvements for the whole building. Many successful rooftop developments have considered the fundamental connections between the urban levels, creating a unity between them whilst attracting visitors. These rooftops have frequently unlocked a new social dimension to the city with often large economic gain.

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Airspace can be sold and bought similar to ground floor sites, creating economic value for disused and underutilised space. The airspace above buildings is commonly owned by the freeholder of the site. The specific height is often deliberated within case law, but originally was translated from Latin to mean ‘for whoever owns the soil, it is theirs up to heaven and down to hell’ (Blackstone, 1765). Whilst not simple, under current planning legislation, the ability to build above an existing building is possible. For example, figure 7 (right) shows where airspace rights have been sold to the benefit of the adjacent site, in this case, to provide additional floor space.

Typically in UK residential developments with leaseholders, the ability of utilising the roof often lies with the management company or the top floor flat holder. In central London, the cost of land on ground floor peaks at ÂŁ9,000m2 (Greater London Authority, 2016) - posing the question, what is the value of our unused airspace?

Fig. 7 - Airspace sold above site in New York for adjacent development

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ROOFTOP PRINCIPLES

// 01

Fig. 8 - Falkestrasse Office Extension, Vienna

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‘If the second ground floor level is to succeed and to make an impact on the rest of the city, it must dazzle.’

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Melet & Vreedenburgh, 2005

Cities across the globe vary drastically for many reasons with diverse social, economic and environmental factors playing large roles. Cities grow (and diminish) over time creating fresh design parameters in which new architecture has to abide by.

Rooftop architecture, whilst currently sparse within global cities, can be characterised into various design categories. Inclusive of both conceptual schemes and built examples, there are various typologies that need to be considered, outlined in the table below;

Relationship

Use

Design

Duration

Parasitic

Topping Up (Extending)

Matching

Temporary

Symbiotic

New Function

Contrasting

Permanent

(An analysis of all precedents against the above matrix can be found in Appendix A)

1.1 PARASITIC VS SYMBIOTIC Two emerging trends of rooftop architecture developed in the 20th Century symbiotic and parasitic. These, as the terms suggest, are diametrically contrasting in approaches in the relationship between the new addition and the existing building.

A parasite refers to ‘an organism that lives in or on an organism of another species (its host) and benefits by deriving nutrients at the other’s expense’ (Oxford English Dictionary, 2017). Parasitic architecture is defined as ‘adaptable, transient and exploitive forms of architecture that forces relationships with host buildings in order to complete themselves’ (Benjamin, 2006), implying that these additions benefit from energy of the host and often identity because of their radical and contrasting presence. A parasitic relationship is often considered to lead to the loss of merit for the host building but it can be argued in some cases the addition might reinforce the character and identity of the building.

One rooftop addition that is considered to be parasitic by many architectural critics is the Falkestrasse office extension in Vienna by Coop Himmelb(l)au (Fig. 8). This parasitic fragmented extension perches on the edge of the rooftop creating a stark contrast to the existing traditional building. Philip Johnson described the addition as ‘appearing to chaotically distort and violently slice the existing building’ (Johnson, 1988).

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Whilst not adhering to the design language of the host, the design adds a dynamic feature to the façade with elements of the abstract design cantilevering beyond the edge of the roof. This is clearly a divergence from the composition of the host and might be considered as a distraction to the historic building façade. The development continually undergoes criticism, particularly its sensitivity to the existing fabric.

Albeit starkly contrasting in design language, the relationship of the addition to the host could also be considered symbiotic as the additional space provides some form of benefit to the existing building, and a challenging visual counterpoint that brings new prominence and identity to this historical building.

Symbiotic relationships benefit both the existing building and the proposed intervention, not exclusively linked to architecture as symbiosis relates to mutually beneficial connections between two or more elements. In the context of rooftop architecture, this translates to both the host and addition benefiting by the development.

‘The new building does not just extend the life of the old building on which it rests, but enhances its significance too’ -

Melet & Vreedenburgh, 2005, p. 21

The Oxford dictionary definition states that symbiosis is ‘a mutually beneficial relationship between different people or groups’ (Oxford English Dictionary, 2017) linking more to social connections between people.

Therefore for any rooftop development to be symbiotic, a connection between the existing building and the proposed intervention is important. This will of course depend upon the existing building’s function, its role (contextual and social) and the nature of the inhabitants. Consideration on the relationship and possible interaction of people is frequently overlooked, with the architectural gesture focusing on its visual and theoretical proposition as having prime importance.

Fig. 9 - Parasite - Paris (Stephan Malka Architects)

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1.2 TOPPING UP VS NEW FUNCTION The redefining of a purpose or function of an elevated plane, allows for it be developed by a variety of uses. Thus, new propositions for the use of the rooftop environment can reflect current desires, such as; renovation, revitalisation, regeneration and reinterpretation. How successful these interventions will be is dependent on site specific parameters and the resultant solution in response to these. Whatever the intervention is, a clear distinction should be made between what is described as ‘Topping Up’ and adding a new function to a building.

‘Topping Up’, a term coined by Melet and Vreedenburgh, describes the vertical extension of the existing building use. They argue that ‘in social, functional and often architectural terms as well, nothing is really added to a building or a district in this way’ as fundamentally the same target group is served (2005, p. 10). The majority of current rooftop projects fall within this category and whilst providing expansion, these additions fail to deal with larger social issues, and instead focus on increasing the economic value by providing additional floor space.

In contrast, adding new functions to rooftops can unlock potential often adding a new social layer to a community. Through additional habitation, rooftop construction adds new activities such as creating room(s) for sports, social interaction, or any additional use the public or residents require. This means that the development is added ‘for a particular reason – architectural, social or economic’ (2005). The ability to add such functions within dense neighbourhoods, could provide local councils, organisations and developers the ability to target specific needs of a community.

A

C B

A

D

A A

B

TOPPING UP

B

NEW FUNCTION

A - RETAIL B - RESIDENTIAL C - BAR D - COMMUNITY CENTRE Fig. 10 - Diagram showing difference between Topping Up and New Function

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1.3 MATCHING VS CONTRASTING Additions to buildings always have a relationship to the host or main building, rooftop additions are no different. Thus, a supplementary design resolution may be assessed on whether the addition will match the building or contrast with it.

Any continuation of the host building vertically relies on careful structural consideration to ensure success. Matching may take many forms, the physical characteristics of the host may be replicated literally or compositionally and materially with window openings and design features replicated in order to create a seamless addition with little or no distinction made between the new and the old.

Similarly by utilising the full footprint of the roof plane, some additions can take the form of traditional mansard roofs, which provides an already tried and accepted unity with the building below. Gaspiri believes that rooftop developments should adapt to the existent, emphasising that rooftop design should respond to the building below (2012, cited by Lucenti & Zamperini, 2014). Commonly, but not exclusively, this relates to topping up, with extensions taking on the use of the current building.

Choosing an opposing stance to the existing building is a bold design decision which sees the rooftop as a creative test ground for new ideas. Sheppard Robson’s rooftop extension to Aldwych House (Fig. 11) created an addition with a distinct identity contrasting that of the historic building which is located within a conservation area. The striking design contrasts with the surrounding traditional mansard roofs on adjacent buildings, creating an architectural statement which contributed in the proposal gaining planning permission. Contrasting in materiality and form, the addition retains the symmetry of the existing building and ‘frames views towards Southbank and the city, while controlling solar gain’ (Rosenfield, 2014).

Fig. 11 - Images of proposed addition to Aldwych House by Sheppard Robson

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1.4 TEMPORARY VS PERMANENT Some rooftop additions provide imaginative solutions, with many of these installed on a temporary basis to avoid difficulties with present legislation, but play a key role in activating the rooftop. Pop up architecture has become a common phenomenon within our cities, and whilst diverse markets sprawl across the ground floor plane, pop up cinemas and spaces for social events are beginning to inhabit rooftops across our cities. Traditionally, temporary additions have been responsive to cities in a state of flux, intended to keep cities active whilst long term solutions are planned (Harris & Nowicki, 2015). Nowadays in order to minimise legislative impact, designers are creating temporary installations that do not require full planning permission, to develop creative and ingenious solutions.

In Milan, Park Associati’s contemporary pop-up restaurant (Fig. 12) currently resides on top of the 19th century Palazzo Beltrami, allowing visitors to travel through the museum to the rooftop to experience being above the city. The installation is flexible, allowing it to be transported to other cities, with the premise of being situated on a rooftop.

In contrast, permanent rooftop architecture has longevity - where temporary solutions are often put in place to solve short term urban issues, permanent solutions solve long term issues. A different design approach is to be applied and consideration of materials and structures needs to be developed to reflect the permanence.

The duration of the development typically relates to its use. Residential units and additional commercial floorspace generate high yields and normally take on more permanent occupation of rooftops. On the other hand, social spaces can be more flexible, allowing an interchange between functions easier than other uses.

Fig. 12 - Pop up restaurant in Milan, Italy

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APPLICATIONS

Fig. 13 - De Urbaniste’s concept image of the potential of Rotterdams rooftops

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‘All the roofs of the city – from very high to low, from large to small and flat or inclined – offer different opportunities to add value to both the owners/users and the city.’

-

De Urbaniste, 2015

In 2015, De Urbaniste worked on generating a framework for Rotterdam called ‘Rotterdam Roofscapes’ (Fig. 15) looking at the potential benefits of inhabiting the roof landscape. Their study focused on maximising the urban roofscape, categorising the roofs into; blue (storm water retention), green (vegetated), actively used roofs and sustainable energy generation (De Urbanisten, 2015). Although categorising rooftops into these four typologies worked for the Dutch city, there are a different set of parameters for UK cities.

Pomeroy defined two categories for rooftop architecture, firstly living and secondly playing, focusing on the activities which would occur within the developments as critical descriptors. This research was carried out in Singapore, where there is a particularly large demand for sustainable solutions. The categorisation that both De Urbaniste and Pomeroy have established, whilst varying, work exclusively to provide a framework for future city development and growth.

Through an analysis of these classifications, three distinct applications have been developed that would appear to be fundamental to the future of urban rooftops within a UK context;

1

Residential rooftop architecture Fundamental for cities to satisfy housing demand and targets which could provide a variety of innovative housing stock.

2

Spaces for social activities Activities that fulfil the need for additional public spaces for sports, culture, activities that enhance health, well-being and leisure – enhancing social cohesion and sustainable communities.

3

Environmentally responsive rooftops This relates to the potential of green / blue roofs, sustainable energy generation and urban agriculture initiatives that benefit the city and its communities.

The following three chapters, appraise and critically analyse these characterisations through use of precedent studies and theories that relate to the potential of these possible uses.

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2.1 RESIDENTIAL Recent UK government studies indicate that we need to build more housing - ‘around 49,000 new homes are required every year in London over the next two decades.’

(Mayor of London, 2015, p.81) The demand for housing is growing due to migration towards cities, with this providing new opportunities for innovative typologies of housing on the rooftops which one could argue is a very seductive proposition for those in the creative industries.

Current estimations for the potential of rooftops in London to support housing, range from 500,000 extra rooms, to 130,000 new homes by Landmark Lofts and 140,000 new homes according to Zac Goldsmith (Crerar, 2016). Utilising under exploited rooftops will not fully address the housing demand, however it is currently underexplored and requires careful consideration to assess how it can contribute to this situation.

A study undertaken by Apex Airspace Development (2015) calculated the potential floorspace within Greater London as being 14,330,080m2. If developed, translated to meeting approximately 42% of the housing target. The research looked into possible rooftop development density to calculate the potential, generally focusing on buildings with flat roofs and not solely residential blocks. In 2016, one year after the study, the Government published in their Consultation on Upward Extensions which stated that ‘only 2% of new homes per year are a result of an element of upward extension’ (Government, 2016). There is a clear difference between the potential and current built examples, highlighting the need for further investigation in this area, to fully assess the possibilities and benefits to both private developers, local authorities and communities.

Conceptual schemes, such as LoftCube, looked into the possibilities of dropping prefabricated homes onto the rooftops via helicopter. The designer, Werner Aissilinger, viewed his intervention as a ‘non – permanent’ way for 21st century living, allowing flexibility for the inhabitants with the potential to relocate (Aisslinger, 2007). Melet and Vreedenburgh consider this to be an ‘over simplistic approach’ (2005) stating that it fails to deal with the fundamental relationship with the existing building, especially in terms of accessibility and service connections. Whilst simplistic and modular in its design, the placing of these spaces have become realised with examples across European cities.

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Fig. 14 - Erection of Lotcube module on top of Hotel Daniel, Austria

Aisslinger’s approach is considered impractical on a city wide and possibly social scale, but is a concept that provokes a possible vision for larger scale rooftop developments becoming more common. When distilled, the concept looks at using pre-fabricated modular units that can be easily positioned on top of existing rooftops, concepts which are only coming into fruition in recent years. LoftCube have undertaken some rooftop developments, albeit with a crane and not a helicopter, placing their cubes on top of hotels and blocks of flats to create premium accommodation. Hotel Daniel in Graz, Austria now boasts a 44m2 rooftop suite with expansive views over the city (Fig. 14).

‘the designers, Studio Aisslinger, were the first to discover that the rooftop in cities can be commercialised and used as a real oasis of calm in urban centres’ -

Serrats, 2010

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In contrast, Falconer Chester Hall’s penthouses at 190-196 City Road, London specifically respond to the roof space and its surrounding parameters. Designed to be subsidiary to the existing building, the contemporary twist on the traditional mansard extension reflects its historic location within a conservation area. The final design, echoing the proposed addition to Aldwych House, suggests a new typology of rooftop architecture. Developed through pre application consultation with Islington Council, the addition has minimal visibility from street level, only hinting at the development which inhabits the roof plane (Fig. 15).

Fig. 15 - Perspective showing proposed impact of rooftop development at 190-196 City Road, London

Rooftop housing will compete with a broad housing market in all cities and if this type of development is going to challenge traditional homes, they have to offer more than the existing housing stock. Whilst in Western countries, living on the rooftop - the penthouse - is considered the pinnacle of city living, ‘the spaciousness of the rooftop building must compensate the lack of garden’ (Melet & Vreedenburgh, 2005). This stance is often disagreed with as space within city centres is at a premium, and rooftops can provide many features, such as city views, a vantage that makes up for the lack of external space. It would appear that the majority of penthouses follow the view that Melet and Vreedenburgh suggest, creating extravagant palaces above the city, but what stops affordable housing from inhabiting these spaces?

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Melet and Vreedenburgh discuss the negative impacts of topping up with respect to residential extensions. They imply that whilst the Government’s proposals for ‘upward extensions would be appropriate on existing residential premises’ (2016), the presence of housing has already been achieved. Whilst this doesn’t mitigate against specific planning policies, it allows potential developers to purchase with the notion of residential development attained.

Rooftop residential development isn’t exclusively linked to topping up, and other examples are beginning to emerge across Western cities. Last year, Tesco identified stores capable of supporting such vertical extensions as part of their real estate strategy, mainly focusing on 15 sites in London projected to release £450 million in resale values (Goldstein, 2017). Other large supermarket brands are following after the successes of Tesco’s flagship development at Streatham, London which saw 250 homes built above the store (Fig. 16).

Developing rooftops to support residential use may have the capacity to create more constraints than other uses. This is down to the need for car parking and amenity for future residents which can often deter developers from developing such sites.

The perceived unknown of rooftop development often discourages potential, with developers and designers not truly understanding the potential benefits. Whilst specific limitations are associated with a residential function, general constraints are discussed further in chapter 3.

Fig. 16 - Tesco Streatham with airspace development of 250 new homes

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Whilst the focus of this writing is on rooftop architecture, there is an understanding of the potential to upwardly extend individual residential homes. Topping up is criticised for adding a ‘lot of the same, without any differentiation in housing’ (Melet & Vreedenburgh, 2005, p. 10), and although in residential terms this normally describes new units on top of existing blocks of flats, rooftop extensions follow a similar concept. According to O’Grady, rooftop extensions are normally carried out for two reasons; ‘a need for additional space and the desire to live or work high above the city rooftops, closer to heaven than to other people’ (2009).

MVRDV’s Didden Village in Rotterdam is a playful extension, contrasting the host building through the use of colour and form. The design focuses on the use of a blue parapet wall, situated on top of the external walls, with two gabled boxes expanding the floor area. The new spaces are accessed via spiral staircases allowing the family to inhabit the once disused roof, creating additional space. The scheme has been described as creating ‘a crown on top of its monument’, and was seen as being a ‘prototype for a further densification of the old and existing city’ (Lomholt, 2010).

Whilst seen as an exemplar in 2010, little evolution has occurred in the subsequent eight years with only a few similar isolated schemes being seen across European cities.

Fig. 17 (above) - Elevations of Didden Village, Rotterdam Fig. 18 (right) - Image of Didden Village, Rotterdam

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2.2 SOCIAL Rooftops are capable of supporting a wide range of social and communal activities - allowing the public to interact with the fifth elevation. Integration of rooftop activities is beginning to filter in new architecture today, and whilst the focus of this thesis is on the re-habitation and re-use of existing rooftops, the progression towards incorporating this new landscape can only be seen as positive and a shift in how Architects conceive buildings. Allford Hall Monaghan Morris’ new build office block next to Silicon Roundabout in London will incorporate a rooftop running track for the use of the workers - promoting a healthier lifestyle.

Rooftop social spaces can work at a variety of scales, from individual art installations, to providing a venue to host large scale social activities. Lucenti and Zamperini consider that numerous hospitals lack recreational and social spaces that would benefit with these types of additions. Social spaces are often created to the detriment of the ‘number of beds or sacrificing the already meagre green spaces at ground level’ but believe that through rooftop additions more useful social spaces could be created (2014). Whilst new facilities may adopt a bioclimatic approach which sees a focus on the well-being of patients and sustainable building solutions, the vast majority of healthcare services are in existing buildings where Lucenti and Zamperini’s approach could be beneficial.

Lucenti and Zamperini’s concept of social space on top of hospitals may have derived from ‘Kinderstad’ in Amsterdam following the successful rooftop addition in 2008 (Fig. 19). The competition won by young Architects Rheenen, Rupali and Gupta visualised the design as a space high above the troubles of the city below with a stronger connection to the sky than the land (Jodidio, 2016, p. 248). The perception of the addition is considered successful by critics through the relationship between the two additional stories and the existing building.

The internal spaces mirror the architecture through making a clear distinction between the hospital below and the communal spaces within the addition. The disconnect from the existing building is contrasted by the connection to the city; artificial football pitches incorporate views over the neighbouring Ajax football training ground and a mock up Schipol airport tower allows users to ‘follow the landing of airplanes with real sound effects’ (Sponge Architects, 2008). These functions are unique and would not be possible without the elevated location of the rooftop.

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Fig. 19 - Image of Kinderstad, Amsterdam

‘The 9th floor stands back from the existing brick-lined building of the eastern wing and from the 10th floor. Due to this gap and the overhanging of the 10th floor, one gets the impression that “Kinderstad” is hovering like a cloud above the hospital’ -

Etherington, 2008

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Fig. 20 - Various images of Rotterdam’s Rooftop Festival

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The creation of new social spaces for users of the existing building isn’t limited to hospitals, with schools, nurseries and offices among functions which could support such spaces. For example, in Birmingham, the rooftop of the Star City shopping centre car park was developed to hold a series of sports pitches, encouraging social interaction and reusing a once disused space within the city.

Creating dynamic public rooftops has been a key driver in De Urbaniste’s proposal for Rotterdam’s roofscape. Integrating rooftop activity into the lifestyles of the inhabitants, Rotterdam has successfully hosted rooftop festivals in which over 40 roofs have been opened up to the public. With the numbers of open rooftops and visitors growing annually, the organizers hope that it will ‘stimulate the utilization of rooftops throughout the city and demonstrate the ways in which rooftops can contribute to a sustainable urban future’ (Ryabets, 2015). The approach taken by the coordinators, in partnership with the municipality, aims at encouraging social interaction through events such as festivals, bars, sports and cinema experiences, whilst educating the public on the untouched potential.

Rooftops are being used for social applications in UK cities, but are sparse and unconnected. Through the creation of city wide events, Rotterdam has been able to create a dialogue between the spaces, linking them either physically or visually.

Philip Jodidio uses the term ‘islands in the sky’ to describe current rooftops as typically there is no connection between them (2016).

Comparatively, Rotterdam has 14.5km2 of potential flat roofs (De Urbanisten, 2015) whilst London has 16.5km2 (Rodriguez, 2009) and although the cities differ geographically, both face similar urban design issues. Rooftops of all heights and scales have the potential to be activated and the outlook from rooftops can vary drastically depending on site specific parameters; height, design and scales of both the building itself and the adjacent buildings. Viewing platforms normally inhabit the tallest buildings, and whilst not a new concept, prove the appeal of urban elevation, highlighting the stark contrast between private and public use of the space. Although frequently designed as public spaces, viewing platforms commonly charge for access, consequently targeting a certain demographic of people.

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2.3 ENVIRONMENTAL It is possible for rooftops to provide a variety of environmental benefits to a city, through the greening of roofs it is feasible to increase biodiversity, reduce the heat island effect, decrease surface water run off volumes and, with the use of solar panels and wind turbines, the production of sustainable energy generation. These all provide a wide range of social benefits to the residents by promoting health and well-being and improving relationships with nature.

Environmentally designed rooftops offer advantages to a variety of building and city stakeholders. Accessibility to rooftops is fundamental in maximising these benefits, with users seeing not just a reduction in energy consumption but also an enhancement in saleability (Mayor of London, 2008). Having access also allows residents to interact with these sustainable technologies, promoting them whilst learning about the potential of the unresolved roofscape.

The uptake of green roofs in London has been ‘a lot slower than in other European and American cities’ which, in a report by the Mayor of London, is put down to the lack of policy and development cost concerns (Mayor of London, 2008). In the report, case study cities were compared to understand the explicit living roof policies, with many cities such as Toronto, Stuttgart and Berlin offering financial incentives for the environmental reuse of rooftops.

Fig. 21 - Aerial images of London (top) and Stuttgart (bottom) highlighting green roofs

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Fig. 22 - Lufa Farms Rooftop Farm in Montreal, Canada

In Montreal, Canada, Lufa Farms (Fig. 22) have combined urban agriculture and rooftop development to create a 3000m2 greenhouse located on the concrete roof of a commercial office building. Through innovative design, the entrepreneurs managed to develop a business model which populates rooftops with steel framed greenhouses, which has since been replicated on both existing buildings and new buildings across the world.

One of the co-founders of Lufa Farms, Hage, describes the greenhouse additions as being in ‘symbiosis with urban buildings to the benefit of both’ (Figlioli, 2010).

A synergetic relationship is created due to both parties mutually benefitting from the development. Lufa Farms benefit due to low rent in urban locations as rooftops aren’t commonly seen as having economic value, with the existing building benefiting from enhanced insulation. The greenhouses also benefit from the vertical stacking of functions achieving a reduction in heating of over a half with heat coming free from the existing building beneath (Hage , 2012).

Borna and Pelsmaker consider that city roofscapes will assist in reducing the carbon footprint of cities through the installation of renewable systems such as solar and wind power (2005). The use of rooftops for sustainable energy generation works at a variety of scales from private dwellings to large public buildings and draws on the specific exposure and orientation of the roof. A report in 2011 by the Environmental Committee of Greater London Authority (GLA) highlighted the potential of PV panels, concluding that over 20% of London’s electricity demand could be met through the effective reuse of rooftops for solar energy (Decentralised energy capacity study: Phase 1: Technical Assessment, 2011).

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// 03

CONSTRAINTS

Fig. 23 - Hearst Tower, NYC by Norman Foster

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Similar to other brownfield sites within UK cities, rooftop development sites come with considerable design and technical constraints that need to be overcome (HTA Design LLP, 2016). Overcoming these constraints can lead designers to inventive solutions, creating unique architecture worthy of their elevated location. Structure, access & fire safety and planning are considered the main limitations and covered in further detail in this chapter, but there is an understanding that many other factors influence the viability of developing rooftops.

3.1 STRUCTURE The structural capacity of a building is the ‘primary factor in determining the feasibility of delivering rooftop development’ (HTA Design LLP, 2016). Early in the viability process, studies need to be undertaken into the ability of the existing building to support a rooftop development. It is conceivable that buildings are capable of holding smaller scale vertical additions as these commonly ‘piggyback on the existing foundations of the host structure, which can support supplementary gravity loads of up to 5%’ (Wong, 2016).

However, larger rooftop developments would require new systems which work with the existing buildings structural system to support any addition. The Hearst Tower in New York designed by Norman Foster in 2003 (Fig. 23), had 46 stories built upon the historic 6 storey building. Structurally, the addition created a unique relationship between the old and the new, allowing for a new steel frame system to sit on existing foundations that required underpinning. The steel columns of the addition ‘pass through the original six-storey stone building below into the ground’ (Warren, 2011), causing large voids to be constructed within the existing building.

Critics argued that the rooftop addition detracted heavily from the design integrity of the host building and whilst the external façade remained untouched, the internal spaces were unnoticeable.

Minimising the load on the host building is fundamental to the viability of a rooftop development. Off-site lightweight framed structures may be more useful to reduce time and disturbance on site, but also allow for smaller tolerances through the use Computer Aided Manufacturing (CAM) software. Structural solutions are typically designed around the existing building, distributing weight onto load bearing elements and attaching to lift shafts for rigidity. Combating large wind loads on these typically exposed elevated sites requires additional consideration with structural designs being comparably greater than similar ground floor projects.

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3.2 ACCESS & FIRE SAFETY Accessibility to rooftops is fundamental in unlocking the potential of the elevated plane and is commonly achieved through an extension of the existing stair or lift core being the ‘most cost effective solution’ (HTA Design LLP, 2016). Typically circulation cores act as shear bracing elements within buildings, protruding up past the roof level to allow for maintenance access.

In contrast, rooftops can be accessed through an independent access which often separates visitors, providing a direct route to the addition and commonly are incorporated within rooftop construction when the host and the extensions use differs. MVRDV created an architectural statement in Rotterdam to encourage residents and visitors to interact with the roofscape through a temporary installation in the form of a scaffolding staircase, allowing users to gain access to the roof of Groot Handelsgebouw (Fig. 24). The 180 step journey allowed visitors to stop and marvel over expansive city views and also hosted talks and musical events.

Accessibility of rooftop development isn’t exclusive for the users as in all buildings it is a fundamental requirement to ensure fire safety standards are met. Rooftop additions are considered new build developments and this means ‘much stricter building regulations apply for this part than for the building below’ (1995 cited by Schagen, 2014), which Groenen considers to be an unrealistic position as the ‘mother building is the weakest link’ in terms of fire safety. An increase in building users also poses a threat to existing fire strategy with potentially more people needing to exit the building in the event of a fire, creating strain on existing means of escape.

Fig. 24 - Rotterdam’s Temporary Scaffolding Staircase

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Fig. 25 - PUP Architects’ Service Duct addition

3.3 PLANNING With no current explicit rooftop planning policies, the UK falls behind other countries in benefitting from these potential spaces.

Richard Warren concludes that ‘it is easier to get planning permission for a rooftop extension in New York than in London’ (2011) predominantly because of the number of listed buildings and conservation areas within London. Goldstein agrees adding that regulations on ‘skyscraper size and protected views in the UK (e.g St Paul’s Cathedral) is more stringent’ (2017) in order to ensure and maintain significant buildings and specific city parameters. The relationship between the rooftop addition, the existing building and the surrounding context is fundamental in achieving a successful design, both in terms of planning and the lifecycle of the building.

Architects and designers constantly challenge the UK planning system to maximise the potential of sites. PUP Architects exploited a loophole in the planning system that allowed for a ‘two-storey service structure to be attached to the top of the roof’ (Mairs, 2017), thus winning the Antepavillion competition to have their design realised on the rooftop of Brunswick Wharf, London (Fig. 25).

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// 04

PORTSMOUTH

Through an analysis of the elements of rooftop architecture, the author has considered the case study of Portsmouth to test out potential applications and theories, in order to determine how rooftop architecture can be beneficial; socially, economically and environmentally for the future development of the city.

4.1 CONTEXT Portsmouth is located on the south coast of England and is one of only two island cities in Europe, alongside Venice. Steeped in nautical history, the population has grown significantly due to industrial demand, and is now the densest city outside of London, with 5,141 people / km2 (Office for National Statistics, 2014).

The roofscape of Portsmouth consists mainly of low lying pitched roofs, typical of terrace housing which dominates large areas of the island. Typically, larger developments and city centre schemes have flat roofs, many of which are underutilised.

4.2 METHODOLOGY In order to explore the benefit of rooftop development for Portsmouth, a study was undertaken to determine the available flat roof space within the city. Pitched and other styles of roofs were omitted for this study, however it is recognised that with a more detailed analysis and evaluation (which would take longer than is possible for this report) some of these roofs might be able to be adapted and modified for specific rooftop developments which respond to the different roof forms.

The following study was carried out with the use of an OS Map, from Edina’s Digimap service, from which Google Maps was studied to analyse the location and typology of the buildings with potential for rooftop development.

Fig. 26 (right) - Total flat roofs with potential for rooftop development

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0 100 200

500

Existing (Host) Building Use Residential

Shopping

Council Building

Office

Shop + Residential (Mixed)

Infrastructure

Leisure

University

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1000m

4.3 RESULTS Use

Size (m2)

Percentage

Residential (including residential above shops)

205,634

42.4%

Office

51,760

10.7%

Leisure

14,106

2.9%

Shop (Food and Retail)

10,782

2.2%

Infrastructure (Car Park etc.)

10,862

2.2%

Public Building (School, Hospital, Council Offices)

163,082

33.6%

University

28,882

6.0%

TOTAL

485,108

100%

Table 1 - Space available by uses of the potential flat roofs in Portsmouth

Extracting solely the buildings in which residential use has been established, the flat roof space equates to 205,634m2 (Fig. 27). Considering Melet and Vreedenburgh’s topping up approach allows for the vertical expansion of the host use, and whilst not adding a new layer to the area, in residential terms, allows for densification.

Based on their expertise, in HTA’s report ‘London’s Rooftops: Potential to Deliver Housing’, they calculated the potential number of additional housing units by taking an average of 60m2 per home, which utilises 75% of the total available roof. This calculation, whilst indicative, meets the minimum floor space standards identified in Portsmouth’s ‘Housing Standard SPD’ and allows for circulation and external amenity for residential units.

Applying HTA’s formula to Portsmouth, it would appear that there is a potential for 2570 new homes, equating to 30% of Portsmouth’s housing target of between 7,100 – 8,400 new homes by 2027 (Portsmouth City Council, 2011). This would be achieved through the addition of one storey to all residential blocks highlighted, of course more units could be created through more than one storey being added.

The percentage is similar to the outcome of HTA’s report in Camden where 28% of their housing targets could be met, indicating a universal opportunity for residential rooftop development across UK cities.

Further analysis carried out by the author of recent planning applications, highlighted the marginal impact that rooftop architecture is having on the city (Table 2). All applications found are for residential use, and many in recent years have been refused by Portsmouth City Council (PCC). Amongst the reasons for refusal, the main objections relate to parking, highlighting one of the limitations to rooftop residential architecture. Melet and Vreedenburgh identified this issue but posed that cities can be more creative in their response with ‘intelligent car parks’ beneath squares and latent voids utilised (2005, p. 148). It could further be argued that with the advances in public transport, we should be designing cars out of cities, thus the demand for parking provision would not restrict housing developments as indicated by the PCC.

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Fig. 27 (left) - Flat roofs with potential for rooftop development where residential use has been established Fig. 28 (right) - Flat roofs with potential for rooftop development owned by Portsmouth City Council

Application Number

Potential Number of Units

Decision

Date (Validated)

17/00954/FUL

1

REFUSE

Jun 17

17/00073/FUL

12

REFUSE

Jan 17

16/01314/FUL

4

WITHDRAWN

Aug 16

16/01057/FUL

3

REFUSE

Jun 16

15/02063/FUL

2

REFUSE

Dec 15

15/00877/FUL

6

PERMIT

Jun 15

14/01667/FUL

3

WITHDRAWN

Dec 14

14/01487/FUL

2

PERMIT*

Nov 14

14/00837/FUL

3

PERMIT

July 14

14/00319/LBC

1

REFUSE

Mar 14

13/00311/FUL

2

WITHDRAWN

Mar 13

12/01119/FUL

4

PERMIT

Oct 12

12/00139/FUL

3

PERMIT

Feb 12

12/00055/FUL

2

PERMIT

Jan 12

11/00990/FUL

7

PERMIT

Oct 11

11/00147/FUL

9

PERMIT

Feb 11

10/00653/FUL

6

PERMIT

Jul 10

10/00315/FUL

3

REFUSE

Apr 10

Table 2 - Analysis of recent rooftop planning applications

* Permission granted after appeal process.

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From the study, searching for key words1 relating to rooftop development on the Portsmouth City Council Planning website, only 18 applications were found relating to the topic in the last 7 years (Table 2). This poses the question, is the lack of explicit planning policy holding back rooftop architecture or is it simply a lack of awareness of the potential?

There are, however, several examples of rooftop architecture across the city as means for densification of residential blocks. These commonly take on the form of matching the existing residential building, creating cohesion between the addition and its host. Figure 29 highlights a residential block where topping up has occurred creating 9 new flats (REF: 11/00147). The existing building has been improved due to the addition attracting an economic gain to the site, creating a symbiotic relationship where both the existing and addition have mutually benefited. The improvements to the existing building undertaken alongside the addition ensured the existing leaseholders were more supportive of the proposal during the planning application process (HRP Architects, 2017).

Buildings which are located within conservation areas require more considered and specific attention to ensure that the addition does not detract from the surrounding buildings. By overlaying a map of Portsmouth’s conservation areas on the potential flat roof study (Appendix B) it illustrates that the majority of useful buildings are located outside of these areas. The results suggest a typology of buildings which are capable of rooftop development, possibly due to the era in which they were constructed as many are post war blocks of flats. Buildings within conservation areas are still capable of vertical expansion as seen in chapter 2 with Falconer Chester Hall’s addition at 190-196 City Road, London where careful consideration was taken to ‘preserve the character and appearance of the conservation area’ (FCH, 2014).

Key Words searched: additional storey, rooftop, airspace, new floor

1

Fig. 29 - Before and After @ Doyle Court, London Road

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Fig. 30 - Portsmouth School with potential rooftop developments highlighted

As discussed in chapter 2, the use of the rooftop isn’t limited to one function or culture. Social rooftops have potential to breathe new life into dense areas of the city through the provision of new activities and space. Schools, hospitals and other public buildings have the potential to support such vertical additions, either providing additional space for the existing building or opening up to the public.

Schools, hospitals, leisure facilities and other public buildings commonly have large expanses of flat roofs and Figure 28 shows the spread of these across the city.

Rooftop playgrounds and sports pitches can provide much needed activity spaces to schools and nurseries within Portsmouth, allowing expansion without additional land consumption. 33,300m2 of flat roof space sits above schools in Portsmouth, typically supporting services, unlocking this potential would allow for the creation of new recreational spaces. With the development of new technologies the need for rooftop services is diminishing and through consideration, the rooftops could begin to become inhabited. For example, Figure 30 (Cliffdale Primary Academy) illustrates the potential for expansion for one of the many schools in the City.

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CONCLUSION Rooftops do not need to be the forgotten elevation within urban locations and reactivating these spaces can form part of a much more enlightened sustainable urban strategy. This thesis presented several possible opportunities that rooftop development can bring to cities and with the migration of people towards cities, it is a fact that we need more space within our urban environments. Rooftop development should reflect the needs and parameters of the city and therefore designed to respond to such conditions for the benefit of both the city and the residents.

Throughout history, roofscapes can be seen as a paradox, answering cultural and social issues of the specific cities of which they are located, from the rooftop slums of Hong Kong to the bars and clubs of New York City. Like any design proposition, it is essential that the proposed development is integrated into the urban fabric of cities and careful consideration is given to the relationship between the addition and the existing.

Through the analysis of precedents, it can be concluded that defining principles for rooftop design are fundamental in determining the success and effectiveness of a project. It is important that the architectural relationship between the host and the addition should respond to the function of the space, furthermore the social relationship between them is just as important - any extension should work in symbiosis with the existing building.

Cities face unique challenges and rooftops can play a significant role in responding to global and city issues whilst dealing with site specific parameters. In response to city wide challenges, rooftops can act as urban acupuncture, placing specific functions into urban voids within the city to improve dormant neighbourhoods. In a UK context, the migration towards cities is met with the need for additional housing in urban locations. Chapter 2 discusses the potential of residential rooftop development and highlights that such development is fundamental for cities to meet their housing targets and it is clear that this can be achieved through pioneering design.

The evidence presented within this thesis illustrates that the development of city roofscapes comes with certain limitations and these need to be carefully considered from the outset. Nevertheless they should not be used to deter development, instead welcomed as challenges in which innovate design can take place and help evolve the existing building to support a new and important purpose. If we as designers look past the constraints, rooftop development becomes a ‘more rational, sustainable and intelligent approach to architecture’ (Serrats, 2010) which focuses on the reuse of existing sites and spaces for inventive architecture.

Fig. 31 (right) - PUP Architects’ Service Duct addition

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Much like all cities, the rooftops of Portsmouth offer the city a wide range of benefits and activities. From views across the city to the coast and the Isle of Wight, rooftops provide a unique approach to connecting with the surrounding urban realm.

This research study highlights the existing roofscape scenario of Portsmouth and suggests possible potential uses built upon the precedents and theories analysed.

This is a statistical analysis looking at opportunities rather than design solutions.

Whilst the study identifies the potential to provide universal opportunities on nearly 500,000m2 of vacant rooftops, further investigation needs to occur to analyse the site specific constraints and limitations.

As the UK moves forward towards a sustainable future, city roofscapes provide the framework for urban renewal, preserving historical layers whilst providing an untouched hinterland for development. Activating rooftops promotes sustainable land consumption and offers a variety of possible uses, unique to each city. These spaces within our cities need to be considered by both designers and planning authorities moving forward, allowing a new growth to occur within cities, supporting their sustainable future.

“We wanted to provoke a conversation about why, if you can build this type of strange plant equipment on the rooftop, why can we not use it in a more positive way, to inhabit and liberate all these hundreds of thousands of square metres of rooftop space?�

-

PUP Architects, 2017

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Portsmouth.

Rodriguez, O. (2009). London Rooftop Agriculture: A Preliminary Estimate of Productive Potential . Cardiff: Welsh School Of Architecture.

Rogers , R., & Burdett, R. (2001). Let’s Cram More into the City. In M. Echenique, & A. Saint, Cities for a New Millenium (pp. 10-13). London: Spon Press.

Rosenfield, K. (2014, Nov). Sheppard Robson Designs Rooftop Pavilion for Aldwych House. Retrieved from Arch Daily: https://www.archdaily.com/565371/sheppardrobson-designs-rooftop-pavilion-for-aldwych-house Ryabets, K. (2015, May). Rotterdam Festival Explores Another Level Of Urban Space.

Retrieved from Pop Up City: http://popupcity.net/rotterdam-festival-exploresanother-level-of-urban-space/ Schagen, L. v. (2014). City Roofs 2.0 – Making use of existing roofs to. Delft University of Technology.

Serrats, M. (2010). Cloud 9: Rooftop Architecture. Barcelona: Loft Publicationas.

Urbanisten, D. (2015). Rotterdam Roofscapes. Rotterdam.

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Warren, R. (2011, June). Tall storeys. Retrieved from Finicial Times: https://www. ft.com/content/aff6f054-9821-11e0-85e9-00144feab49a?mhq5j=e7 Wong, L. (2016). Adaptive Reuse: Extending the Lives of Buildings. Basel: Birkhauser.

Wu, R., & Canham, S. (2009). Potraits from above - Hong Kong’s Informal Rooftop Commuities . Hong Kong: Peperoni Books.

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SOURCE OF ILLUSTRATIONS

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Ariel View of Commercial Road, Portsmouth Source: CJB Photography Rooftop of Unite D’Habitation by Le Corbusier Source: https://www.flickr.com/photos/ninkwink/5164604789 Timeline showing progression of Rooftop Architecture Author’s own work Skyscraper City - Seielstad Source: http://www.airships.net/futurism/ Haus-Rucker New York Concept (1971) Source: http://www.frac-centre.fr/collection/collection-art-architecture/index-des-auteurs/auteurs/ projets-64.html?authID=260&ensembleID=858 Hong Kong rooftop communities Source: https://i.pinimg.com/originals/e6/ee/55/e6ee5502f717b9e00e485e816b4b6f6d.jpg Airspace sold above site in New York for adjacent development Source: http://www.nycblogestate.com/2013/05/nyc-air-rights-unused-development-rights.html Falkestrasse Office Extension, Vienna Source: https://wienhaesslich.wordpress.com/2011/03/12/73/ Parasite - Paris (Stephan Malka Architects) Source: http://edition.cnn.com/style/article/parasite-architecture/index.html Diagram showing difference between Topping Up and New Function Author’s own work Images of proposed addition to Aldwych House by Sheppard Robson Source: https://www.sheppardrobson.com/architecture/view/aldwych-house-wc2 Pop up restaurant in Milan, Italy Source: https://www.arketipomagazine.it/miarch-2016-40-constructions/ De Urbaniste’s concept image of the potential of Rotterdams rooftops Source: http://www.urbanisten.nl/wp/wp-content/uploads/URBANISTEN_Rotterdam_Rooftop_Potential_ EN.pdf Erection of Lotcube module on top of Hotel Daniel, Austria Source: http://living.corriere.it/tendenze/architettura/loftcube-hotel-daniel-graz-50366700188/ Perspective showing proposed impact of rooftop development at 190-196 City Road, London Source: Planning application // Design and Access Statement Tesco Streatham with airspace development of 250 new homes Source: http://www.apexairspace.co.uk/race-airspace-continues-london/ Elevations of Didden Village, Rotterdam Source: https://www.archdaily.com/13370/didden-village Image of Didden Village, Rotterdam Source: Source: https://www.archdaily.com/13370/didden-village Image of Kinderstad, Amsterdam Source: http://tyzhden.ua/Gallery/56235 Various images of Rotterdam’s Rooftop Festival Source: https://www.rotterdamfestivals.nl/en/agenda/rotterdamse-dakendagen/ Aerial images of London (top) and Stuttgart (bottom) highlighting green roofs Source: Google Maps Pro - Author’s own diagram Lufa Farms Rooftop Farm in Montreal, Canada Source: https://urbanecologycmu.files.wordpress.com/2015/10/lufa_farms_aerial_view_of_montreal_ rooftop_greenhouse6.jpg Hearst Tower, NYC by Norman Foster Source: http://2.bp.blogspot.com/-9PT5dr_QEUc/Uv_AhxIETaI/AAAAAAAAAFw/n0KK356xlUg/s1600/ img0.jpg Rotterdam’s Temporary Scaffolding Staircase Source: https://www.domusweb.it/en/news/2016/05/19/mvrdv_the_stairs/_jcr_content/image-preview.img. rmedium.jpg/1463671095519.jpg PUP Architects’ Service Duct addition Source: https://www.dezeen.com/2017/08/04/pup-architects-roof-pavilion-antepavilion-air-duct- architecture-foundation-shiva-london-hackney/ Total flat roofs with potential for rooftop development Author’s own work Flat roofs with potential for rooftop development where residential use has been established Author’s own work Flat roofs with potential for rooftop development owned by Portsmouth City Council Author’s own work Before and After @ Doyle Court, London Road Source: Google Maps Pro Portsmouth School with potential rooftop developments highlighted Source: Google Maps Pro - Author’s own diagram PUP Architects’ Service Duct addition Source: https://www.dezeen.com/2017/08/04/pup-architects-roof-pavilion-antepavilion-air-duct- architecture-foundation-shiva-london-hackney/

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BIBLIOGRAPHY

Armstrong, A. (2016, Nov). Tesco speeds up plans to build homes on stores and car parks. Retrieved from The Telegraph: http://www.telegraph.co.uk/ business/2016/12/17/tesco-speeds-plans-build-homes-stores-car-parks/ Betsky, A. (2005) Preface, in: E. Melet & E. Vreedenburgh (Eds) Rooftop Architecture.

Rotterdam: NAI. Brotrück, T. (2007). Roof Construction - basics. Basel, Switzerland: Birkhäuser Publishers for Architecture.

Bruegger, S. L. (2012). Building on the City: Inhabiting the Rooftops as a Strategy for the Urban. Dalhousie: Thesis .

Building Talk. (2016, Nov). Retrieved from Tesco to build homes – every little helps!: http://www.buildingtalk.com/tesco-to-build-homes-every-little-helps/ Cheng, V. (2010). Understanding Density and High Density. London: Earthscan.

Davids, I. (2015, June). Rotterdam Roofscapes: From history to a sustainable future.

Retrieved from Studio Rotterdam: http://rashiq-fataar.squarespace.com/blog/ rotterdam-roofscapes Hall, P. (2002) Cities of Tomorrow. London: Blackwell.

Gökçe, E. (2015). Rooftop Architecture in Instanbul. Namik Kemal University, 25-27.

Pierre, C. (1974, March). Heavens above. New York Magazine. New York: New York Media, LLC. Rowe, D. B. (2010). Green roofs as a means of pollution abatement. Elsevier, 159(Environmental pollution).

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Application

Office Office Restaurant Residential Residential Residential Social Agriculture Office Residential

Project

Falkestrasse office extension by Coop Himmelb(l)au

Sheppard Robson’s rooftop extension to Aldwych House

Park Associati’s Palazzo Beltrami

Loftcube

Falconer Chester Hall’s penthouses on 190-196 City Road

MVRDV’s Didden Village

Kinderstad

Montreal, Canada, Lufa Farms

Hearst Tower in New York

PUP Architects’ Service Duct

Parasite

Symbiotic

Topping Up

New Function

Analysis of precedents used against matrix set up in Chapter 1 // Rooftop Principles.

Matching

Contrasting

Temporary

Permanent

APPENDIX A

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APPENDIX B

Total Developable Flat Roof space identified in study;

Portsmouth’s Conservation Areas

(source:https://www.portsmouth.gov.uk/ext/documents-external/dev-all-cons-areas-map.pdf)

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