Book about roof structures: City extensions in the vertical

When it first built a new building on the roof of an old building in the historic center of Vienna in 1988, the Austrian duo of architects “Coop Himmelbau” got into trouble with the preservation order.

Because their deconstructivist explosion violated all conservation rules, the architects called on the mayor at the time, Helmut Zilk.

He enforced the building permit with the argument: This is not architecture, this is art.

The architectural pioneering Viennese project forms the prelude to a stimulating collection of twenty-four roof structures, which today want to contribute far beyond the architectural aesthetics to the socio-ecological urban redevelopment.

Because vertical city extensions create new building plots without soil wear and tear and thus growth without urban sprawl, they upgrade existing buildings and also strengthen the neighborhood with open spaces for urban greenery, communal facilities and sometimes also restaurants.

In the corset of the Belle Époque

Fortunately, the book by Turin architecture professors Gustavo Ambrosini and Guido Callegari does not come as a kilo-heavy illustrated book full of luxurious penthouses, but as a brief cicerone on small and large, pretty and ugly roofscapes around the world. This bird's eye view shows the need to catch up with today's architecture, not only in terms of design, but above all in the use of verticals. The authors rightly criticize that the beautiful idea of ​​modernity to create a “fifth facade” for gardens, sports facilities and recreation rooms with flat roofs instead of pitched roofs only resulted in asphalt technology dumps for antennas, machines, lines and tanks.

These devices have mostly disappeared in the building examples - unfortunately, it is not shown where.

But it can be assumed that the conversion of the hot summer rooftop deserts into lively and planted common rooms also makes a lot of house and air-conditioning technology superfluous.

The authors examine three types of additions - historic residential buildings, converted industrial buildings, and public facilities.

Shiny silver Snow White coffins

In Vienna and Paris it is noticeable that the city centers above the eaves have long been built over with acropolis, high-rise cities of lofts, maisonettes and studios that are not even visible from the ground.

In Vienna, thanks to the local artistic freedom, structures loll more wildly than in Paris or Barcelona, ​​where the upward expansion of the city is visually and constructively in the corset of the Belle Époque.

But also in Copenhagen or Mexico City, historical houses are being freed from their pitched roofs and completely redefined with apartments, terraces and vegetation.

While before the invention of the elevator the piano nobiles were on the first floor and the servants' chambers under the roof, the hierarchy has been reversed.

But apartments for millionaires are no longer just being built upstairs, but also for social tenants.

Constructions like in shipbuilding

The book shows subsidized attic apartments in Milan and Cologne.

The examples of industrial buildings with partly rough, rusty sheds, partly silver-shining Snow White coffins - the examples come from Antwerp, Tallinn, Budapest and Shanghai - are not unaffordable, according to the authors;

the construction costs should be one to three thousand euros per square meter.

The overly short project descriptions with tiny ground and floor drawings unfortunately lack constructive and building law explanations.

One of the bizarre examples comes from Stockholm, where the Equator architecture firm built a small village over the flat roof of a former post office.

The architects Sauerbruch Hutton put a new Belvedere with 3600 square meters on a block perimeter at the Metropolitan School in Berlin-Mitte.

For weight reasons, prefabricated wooden frame constructions were used similar to those used in shipbuilding, and with its noble copper facade, the lively new construction even tears the old GDR panel underneath from its brown-tiled dreariness.

The prudery of monument protection

The references to the funding policy for roof landscapes in European metropolises are instructive. Paris, which is already intensely built up and inhabited, abolished many density restrictions in 2014 and even called on homeowners to expand their old buildings with ten thousand new attic apartments every year. In Great Britain, every house can have two new floors with a total height of up to thirty meters without any approval hurdles. Even in Spain and Austria, the sky is not blocked with monument, milieu or fire protection requirements.

What is missing is a comparison of European building vacancies with German blockades. In addition to the prudish of monument protection, the local fire brigade has also made the inner-city increases unaffordable with increasingly gigantic fire engines. Where the mandatory second escape route used to be next to the stairwell via the mobile rescue ladders, now expensive fire staircases have to be built because the giant ladder carts no longer fit into a city street.

In summary, the authors calculate that around 24,000 square kilometers of floor space in the EU is sealed with buildings.

The majority of them come from the post-war period and require energetic, technical and aesthetic training.

In particular, the porosity of so-called sponge cities, which is required in the face of climate change, could begin to protect the soil and make roof deserts on old and new buildings bloom for people.

Gustavo Ambrosini and Guido Callegari: “Roofscape Design”.

Regenerating the City upon the City.

Jovis Verlag, Berlin 2021. 176 pp., Ill., Br., 28, - €.