Additional depth: topping is on the rise, but on a large scale it is still a long way off

Optopping is in the spotlight because of the enormous housing shortage. There are also several initiatives in this area in Amsterdam. However, the large-scale implementation of topping is not yet in the offing: this remains difficult due to the costs, the construction itself and especially the regulations.

Does topping up offer a way out of the housing crisis? There is room for 100,000 additional homes on the roofs of existing flats throughout the Netherlands, thinks outgoing minister Hugo de Jonge. And as far as Thijs Müller, from Creative City Solutions, is concerned, around 10,000 new homes can be built in Amsterdam. According to the company’s own research, which guides homeowners’ associations with sustainability and top-up projects, the potential lies mainly in post-war gallery flats, often in Buitenveldert.

Housing associations are also investigating topping, but are more cautious than Müller. This is partly due to past experiences, says Erik Nagengast, Real Estate Director at the Rochdale housing association. “We have encountered technical problems in the past. For example, you have to properly lower the pipework. These have been expensive lessons,” he says.

The corporation is now again refraining from large-scale topping, because it is quite complicated from a construction point of view – and expensive. “It is a complex task for relatively few homes. Because you can only add one or two layers to an existing building, which also makes it expensive,” says the director.

How safe is topping?

Topping often uses light and durable materials. In recent years there have been several fires in the facade and roof construction of sustainable homes, where the fire was not limited to one home. This is also the case on the Joan Muyskenweg.

The NIPV (Netherlands Institute of Public Safety) recently warned in a report that in sustainable homes there is a risk of rapid and unpredictable fire spread. The NIPV concludes that current building regulations are inadequate to limit the risks of fires when using new (flammable) building materials and construction methods.

Another point: the safety requirements. If homes are built on an office, the office safety requirements continue to apply to the entire building. According to the Amsterdam-Amstelland Fire Department, it is safer if owners adopt the fire requirements of the new function of the building.

However, their report on the fire on the Joan Muyskenweg shows that the fire safety of the new situation was taken into account. “However, that fire had little to do with the permitted level, they were very unlucky there,” says a spokesperson.

Müller thinks that costs can be a lot lower if top-up work is carried out at the same time as renovation jobs. “We are now at a point where we are wondering what we are going to do with those buildings. You can knock them down, but it is more sustainable to create a new floor. This creates a revenue model to cover the overdue maintenance and sustainability ,” said Müller.

However, his concept faces obstacles. According to Müller, construction costs have risen considerably in recent years and municipal policy is not exactly helping.

Resistance

The age-old leasehold system in Amsterdam, among other things, makes structural topping complicated. If a property increases in value, for example due to topping up, the municipality can increase the leasehold. According to Müller, this does not make it attractive for a manager to make the investment.

He would also like to limit the participation rights of homeowners’ associations. “Right now, 100 percent of people have to agree. Although it is very important to hear everyone, this makes it very difficult at the moment,” he says.

However, Councilor Reinier van Dantzig has stated that he does not want to change this. “Rules are also there to protect Amsterdam residents and prevent everything from having to be fought out in court,” he says. Van Dantzig says he is enthusiastic about the small-scale possibilities – within the current rules. “I really see it as tailor-made,” he says.

The large scale that Müller wants is therefore still far away. Still, he hopes that companies and the municipality will drop their hesitation. He appeals to the symbolism of the post-war gallery flats. “These were built during the reconstruction period, when the government joined forces with municipalities and market parties to systematically build as many homes as possible in a short time. We actually need that mentality again.”