Under the sky of Stone Town, the roofs become the horizon and the skyline the background
© arcomai I The built horizon of Stone Town.
The skyline is defined as the outline of the overall view delineated by the buildings of a city and its highest points (roofs, domes, towers, spires, antennas). The term can also be used to refer to the built landscape of a town as one of the most significant signs of power, culture and wealth expressed by it. In this sense, the “skyline” represents the synthesis of the civil, economic and cultural peculiarities of a society. The “urban horizon”, drawn by the roofs of Stone Town, capital of the island of Zanzibar (Tanzania) in the Indian Ocean, generates a panorama unique in the world that delineates a profile similar to that of an artificial relief; a “built horizon” that at certain times of the day contrasts with the cloudy sky, balancing its volumes; while at other times it acts as an outline, moving the clear sky to a background plane. Therefore, a skyline that is always evolving because the elements, divided by this imaginary line, change according to the seasons and atmospheric conditions.
© arcomai I Skyline of Stone Town.
Stone Town is one of the most historically important cities in East Africa. Its origins date back to the 1830s when the first coral stone houses were built, hence the name “Stone City”. Thanks to its historical and architectural importance, the city was declared a UNESCO World Heritage Site in 2002. The city’s urban layout is characterized by a maze of alleys defined by houses, palaces, shops, open spaces, squares, bazaars and mosques characterized by a unique mix of styles that includes Moorish, Arab, Persian, Indian and European (colonial) elements. Because of this morphological peculiarity, Stone Town is not properly a city of architecture since the elevations of its buildings cannot be perceived (in their entirety) by visitors apart from the typical carved doors and balconies. If you want to see the buildings in their entirety, you have to climb on the roofs. The real facades of the buildings are their roofs.
© arcomai I Skyline of Stone Town.
Currently, the built environment is essentially covered in corrugated metal sheets; a ‘metal carpet’ of at least 86 acres (35 hectares), a visibly rusted patchwork, sometimes assembled in a rough manner. This not only gives a homogenized image of the Stone Town skyline, erasing the original volumes of the buildings, but also contributes to making the city appear like a luxury bidonville (shantytown) – a “bidon” in French means a “metal can” -, giving it a shabby, precarious, and dilapidated appearance. Corrugated sheet metal was already in use (in Europe) around the second half of the 19th century to cover stations, barracks, factories, and warehouses. The British, Germans, and French also used it for their colonial buildings in both Africa and Asia. Most likely, the British brought this material to Stone Town during their protectorate, as evidenced by some historical photos from the early 20th century.
Metal sheet (corrugated, galvanized, or zinc-coated) – in addition to making a roof perfectly waterproof – is lightweight, easily transportable, simple to install, and relatively inexpensive. A “dream of modernity” that makes it, even today, a very common and difficult-to-replace building element. The advantage is enormous – especially in slums – also thanks to the ease of recycling the material. Conversely, its main defect undoubtedly concerns the poor internal comfort of buildings due to both heat transmission and the “drum effect”, inevitable during heavy downpours of rain which, here, during the rainy season, last for several months of the year. Furthermore, the covering sheet metal can reach high temperatures during the day, making the internal environment uninhabitable.
© arcomai I Alleys of Stone Town.
Conversely, these panels cool down quite quickly as soon as the sun goes down due to the low thermal inertia of the metal and the minimum thickness of the elements. However, if the ventilation of the internal environments is poor, the heat accumulated during the daytime can remain for a long time even during the night. To reduce the problem, two paths can be tried: internally, separating the roof from the interior with “false ceilings”, insulating or large air gaps; externally, trying to reduce radiation by applying shading elements to the sheets. Alternative uses and functions of the roof and/or attic could be an incentive to adopt more sustainable and efficient innovative materials and/or try to improve the – now consolidated – one, bringing it to achieve technical requirements and aesthetic properties more relevant to the urban and historical context of Stone Town. The built heritage of Stone Town is largely in decay, both due to the friability of the local stone, with which most of the buildings are built, and due to the lack of care by private individuals and public bodies, although a specific Conservation Authority has been established and the city has been under the aegis of UNESCO for twenty years.
Of the approximately 1600 buildings that make up the ancient city, only a tenth receive proper maintenance. Many are dilapidated or unsafe, if not even collapsed, like the House of Wonders of 1883 (the Palace of Wonders, residence of Sultan Barghash bin Said) which partially collapsed last December 25th. Therefore, even artifacts of particular historical significance are among the most fragile and often neglected despite their importance. It goes without saying that to safeguard the buildings it is necessary to intervene on their most sensitive part: the roof. We therefore start from the “built horizon” of the capital of Zanzibar to think of a program that secures its building assets and at the same time serves as a pro-active tool for urban regeneration in a broad sense.
© arcomai I Skyline of Stone Town.