Work started on the world’s future tallest timber residential and commercial building in October. But even before the first glulam, cross laminated timber and concrete components of Vienna’s 24-storey HoHo building were delivered to site it had already notched up successes.
HoHo, short for Holzhochhaus, or timber high-rise, was named national best-mixed use building in the International Property Awards in early November. Early interest has also been reported in renting apartment and office space – and the 25,000m2 building additionally includes a hotel.
Given planning permission last year, the €65m development will comprise around 74% timber, distributed between its structure, interior build and external cladding, according to architect Rüdiger Lainer + Partners. The remainder will comprise concrete for additional supporting elements, stairs and lift shafts, and steel in the form of connectors.
A spokesperson for the architects said this materials blend combined the environmental benefits of using 3,600m3 of Austrian spruce and the structural advantages of underpinning engineered wood with concrete.
“The timber gives a CO2 saving of 2,800 tonnes compared to building purely in steel and concrete,” they said. “At the same time, we avoid compression issues of using only engineered wood in such a tall building. The glulam columns, to which the CLT is fixed, rest on concrete beams. The wood composite floors also link to reinforced concrete core structures and extend out to the façade, where they’re supported by the wood columns.”
The façade will also be innovative, said co-developer investors Kerbler Holding and cetus Baudevelopment. Manufactured by Zublin Timber, which recently supplied the US tulipwood CLT panels for the American Hardwood Export Council’s Smile showcase at the London Design Festival, the structure will comprise a “solid wood panel and mineral shell sandwich”.
The building’s scale and level of novel design and engineering innovation – courtesy of Woschitz Group (www.woschitzgroup.com) – naturally attracted scrutiny by building control. A key concern was fire safety, but that was dealt with through a range of measures. Interior solid wood surfaces are left unclad for ready inspection, concrete and timber structures are mutually supportive, but separated, and protective systems include sprinklers and forced draft staircases and elevator shafts. In short, said the architect, the building’s fire risk is comparable to its equivalent in concrete and steel.
Hoho is due for completion late 2018 and, such is Rüdiger Lainer + Partners’ confidence in its structure, it is already interested in going bigger and better.
“We’d like to use the know-how in further projects,” it said. “And it is possible to go higher in wood.”
