Building upwards in urban areas: luxury penthouses or a social housing solution?



Roger Baltus's column #2

Building upwards in urban areas: luxury penthouses or a social housing solution?

In large cities, raising the height of buildings often results in generously sized lofts complete with terraces. Is building rooftop extensions an opportunity to be seized in terms of meeting social housing requirements? My thoughts on the question, to contribute to this public debate.

Design and decoration magazines are full of examples of generously sized lofts complete with terraces built on rooftops. The price per square metre of these fashionable apartments is equivalent to those in sought after areas of large cities.
Have light and a view become the new signs of wealth? History eternally repeats itself.

In the 19th century, the last storey and attics of urban buildings were set aside for domestic staff. Servants and labourers had to climb dark, steep, narrow staircases to get to their tiny attic rooms. Wealthy people lived on the lower floors. Their spacious homes had large windows and “healthy” high ceilings. Georges Perec's novel, “Life: a user's manual”, provides a wonderful description of this social structure of housing in a Parisian building of the period.

The invention - and subsequent democratisation - of the lift in the 20th century gradually changed this situation and reversed the hierarchy of value of apartments. In essence, the higher the storey, the brighter and sunnier the apartment, hence the higher its price.

In large European cities where land is scarce, horizontal extensions are no longer possible. Large cities are therefore looking to increase space by building upwards. These urban elevations take on various forms: lofts on top of office buildings (photo 1 – Brussels), high-end apartments on top of a former industrial plant (photo 2 – New York), housing units on top of an old bunker (photo 3 – Germany)

Why are these roof extensions considered as luxury apartments? Three main difficulties increase the overall cost of work. Procedures to obtain co-owners' agreement are long (minimum two years) and complex. To convince the occupants of the existing building, developers propose installing a lift or renovating the roof and insulation or sometimes even the creation of new communal areas. In addition to this concept of compensation, the complexity of building on an occupied site located in city centre neighbourhoods with restricted accessibility is a second major difficulty. Lastly, urban planning constraints (restriction of surfaces, alignment recesses, integration …) impose forms and materials that significantly increase overall costs.

Given these conditions, is raising buildings unaffordable for social housing? Recent programmes demonstrate the feasibility of these projects. In Paris, architect Marie Schweitzer magnificently renovated a 261-room hostel in a building in rue Tolbiac in the 13th district of Paris. This three-storey roof extension with wooden structure and cladding (including creation of studio apartments, offices and communal areas) was awarded the CSTB Innovation Prize at the 2014 FIMBACTE Festival. The 800 m2 platforms were entirely prefabricated in workshops. Installation at the occupied site was completed in six weeks. Marie Schweitzer admits it took a lot of energy to convince the parties involved that the project was feasible. The trust of the client (Domaxis/Aftam) and the district mayor made it possible to overcome misgivings.

So elevation is an opportunity to be seized in terms of meeting social housing requirements. In this regard, the State has a significant role to play. For example by making public buildings with flat roofs available (over 2,000 buildings in Paris!), by making it easier to obtain planning permission (especially via the law on abolishing the right of veto of the occupant of the last storey) and by promoting less costly prefabricated solutions.

It is worth noting that technical solutions for roof extensions (lightweight frameworks) are identical, regardless of the standard of accommodation.
This is a civic – and little known - democratisation of the latest building techniques and also a source of job creation.
Worth knowing and sharing.

*Prix Médicis, published in 1978

Roger Baltus
Engineer- Architect
VMZINC Communication Director


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