Countdown for the world’s tallest timber apartment building
Ground planning and technical preparations for the 96-metre-landmark Burj Zanzibar are almost complete. “From our side, we could start building tomorrow”, construction experts say. Developer CPS intends to kick-off in 2024. THE FUMBA TIMES visited a similar timber tower in Germany to assess chances and risks.
The holiday island Zanzibar is aspiring to get an outstanding global environmental landmark, the highest hybrid timber apartment tower in the world. Preparations for the extravagant green building have been continuing since the news broke last December. Media all over the world, from the London Times to the Economist, have reported about the green lighthouse project.
THE FUMBA TIMES visited the construction site of a very similar project in Hamburg – the highest wood apartment building in Germany. With 19 floors on 65 metres, the Roots tower is almost ready to move into. It was constructed without delay in just over three years. The Hamburg tower has 181 apartments, 53 of them social housing, as legally required in Germany. But the price of the luxury flats in best location is as sky-high as the building: $10,000 per square metre. For the Zanzibar landmark of even larger proportions, more than 30 percent of the 136 planned tower apartments have already been sold off-plan, disclosed Sebastian Dietzold, director of developer CPS, who initiated the project.
“Groundbreaking could take place around August-September next year, when we expect to have sold 60- 70 percent of the units”, Dietzold said. Prices for stunning holiday and residential apartments with panoramic views presently range from $79,900 to $959,880. They are likely to increase once construction on site commences.
How ideal is timber for the tropics?
Can such a building really be built in Zanzibar, a tropical country? Are safety, stability and longevity guaranteed? I am standing on the rooftop of Roots, 65 metres high, a strong northern wind is blowing while I am posing these questions to architect Fabian von Koeppen. His company Garbe Real Estate is building Germany’s highest timber building. The futuristic HafenCity (German for ‘Port City’) lies to our feet like a toy city. “Once the building is standing, stability is no problem, timber is actually more stable than concrete because it is lighter”, the 53-year-old managing director explains.
“The most difficult phase is the construction when large pre-fab walls have to be lifted by crane.” He has had to halt the assembly process several times due to heavy winds. His positive message: “In the tropics, a timber building is even more suited than in northern Europe because of the constant humidity. In Germany, we have to handle temperature changes from minus 20 to plus 30 degree with a flexible construction to allow for the wooden parts to shrink and expand.”
Looking around, I can see the entire outer façade of the rather plain building is made of original wooden planks while inside the walls are covered by white plasterboard. Glass sliding doors seal the front of balconies. Why? “Wind and rain protection”, von Koeppen says, “inside, most homebuyers did not want to see knotholes of wood but a pure look.” Crazy, I think to myself, that a sustainable building has to cover-up its wooden elements for style reasons! Architect von Koeppen has become a crusader for timber in Hamburg. “We will create a forest of houses”, he says, “and reduce the CO2 footprint by up to 145 per cent compared to conventional building.” The world’s oldest building material has a renaissance. A fifth of new residence houses in Germany were built with timber over the last few years.
The seaside community Fumba Town in Zanzibar is already constructing townhouses, villas – and now the Burj – with timber technology. What exactly can tourists and holiday apartment buyers expect in Fumba? “Dimensional stability, stunning architecture, a sustainable lifestyle” promises Professor Thorsten Helbig, one of the world’s most renowned structural engineers and part of the expert consortium to construct the Burj Zanzibar. Helbig regularly commutes between New York and Stuttgart, I catch up with the 56-year-old in Germany. The structural backbone of the Zanzibar tower, Helbig explains, is a “steel-enforced concrete core and a hybrid foundation of six floors”. The concrete core guarantees fire protection. A top global hotel chain is expected to occupy the ground wing of the Burj. The stunning beehive design of the tower with large panorama windows and cubic green terraces will be seen from the airplane when approaching the island.
One floor per week
Conventional construction with cement is responsible for 35 per cent of greenhouse emissions while wooden buildings do just the opposite and store CO2 like a battery. A 4,000 cubic metre building like the Burj binds 3,200 tons of carbon dioxide.
Wood is a fully re-growable raw material.
Timber construction is faster and more precise than conventional building because of its pre-fab elements. “In Zanzibar we can assemble one floor per week”, forecasts engineer Prof. Helbig.
The pre-fab timber elements made of glulam and cross-laminated timber (CLT) will be produced by Binderholz, a global leader in timber construction, in Austria. In the long run, however, the Burj is meant to jump start agroforestry and timber technology in Tanzania and to create valuable jobs. “The battle for sustainable building is being fought not in Europe but in Africa because of the continent’s vast potential agro-forestry and high population growth”, noted Prof. Helbig.
But as many similarities as timber landmark projects all over the world may have, they distinctively differ in price: a one-bedroom in Hamburg starts at half a million dollars, in Zanzibar at $119,000.