(pictured above: Norway’s Mjøstårnet building is the world's tallest timber building, but will be overtaken by the Ascent building which opens in July) As the number of timber skyscrapers which have either opened, are under construction, or are proposed continues to grow, momentum toward greater use of mass timber in multi-storey construction continues to gather pace around the world.
In its latest study, the Council on Tall Buildings and Urban Habitat has completed a global audit of tall mass timber buildings – buildings which are either eight storeys or higher and which are constructed either entirely of timber or are a hybrid involving timber with steel, concrete or both.
It found that worldwide, there are now 139 mass timber buildings which are either completed, under construction or proposed.
Of these, 66 have opened whilst eighteen are under construction and a further 55 are proposed.
This compares with no such buildings which met this definition prior to 2009.
According to the audit:
- A total of 139 mass timber buildings of eight storeys or above in height are either completed, under construction or proposed.
- Of these, 66 are completed and 18 are under construction whilst a further 55 are proposed.
- Of the 84 buildings which are completed or under construction, two thirds (54) are residential whilst 16 are office buildings, 12 are mixed use buildings and a further 2 are institutional buildings.
- Of the 84 tall mass timber buildings which are either completed or under construction, 60 are in Europe whist a further 15 are in North America, 8 are in Australia and only one is in Asia.
- Whilst all-timber buildings have been common in mass timber construction, recent years have seen a growing prevalence of concrete and timber hybrid buildings.
Invented in Australia and Germany in the 1990s, mass timber construction has gained growing prominence in multi-storey buildings.
Mass timber uses state of the art technology to glue, nail or dowel would products into layers which deliver large structural panels, posts and beams which are strong and versatile.
Its growing popularity reflects its light weight relative to its strength (which makes it easier to work with and reduces the amount of footing required to cater for its vertical load); its lower environmental footprint (provided that it is sustainably sourced and harvested) as a material that is natural and renewable; its strong thermal performance and its aesthetic and wellness qualities associated with it being a natural material. In addition, timber is also well-suited to offsite manufacturing.
As things stand (for now), the current tallest building is Norway’s Mjøstårnet building (pictured above).
Set on a site which lays on the riverbank of the small city Brumunda (10,000 residents), the building overlooks Lake Mjøsa – the largest lake in Norway and its surrounds.
Standing on top of the viewing platform, one can look across the lake to the forest from which the timber was sourced and processed locally in an area famous for its forestry and wood processing industry.
The building itself stands at eighteen storeys or 85.4 meters.
Features include a public ground floor with lobby, reception and restaurant; building services and conference floors; five office storeys; a four-storey hotel; 33 residential units with balconies overlooking the lake on floors 12-16; and the top two floors which are divided into three further residential units, an exhibition room and a public terrace on both the 18th and 19th floor.
This, however, will be overtaken by the Ascent building (pictured above) in the East Town neighborhood in Milwaukee, Wisconsin.
When it opens in July, this will stand at 25 storeys or 86.6 meters (284 ft).
The 493,000 square foot, mixed use building will contain 259 apartments, a pool on the sixth floor and a top floor amenity level.
The mass timber residential floors are constructed above five levels of concrete parking garage. A system of glue-laminated timber (glulam) beams and columns support cross-laminated timber (CLT) floors. Two concrete cores provide lateral stability.
The design exposes the mass timber construction wherever possible to display its natural qualities.
Fire testing proved that the timber structural members meet or exceed fire rating code requirements.
An efficient system of post-tensioned concrete beams transfer loads from the timber residential floors to the concrete garage structure below.
The superstructure is supported on concrete-filled steel pipe piles – the highest capacity piles yet built in Wisconsin. This system minimizes material quantities and reduces installation time, for substantial cost savings.
The use of sustainable mass timber helps the building exceed Milwaukee’s energy conservation code requirements.