In mid-rise construction, Cross-Laminated Timber (CLT) is a real threat to concrete and steel, for good reason.
CLT panels are strong, stable, fire resistant and made from a renewable resource: wood. It is also lighter than concrete, faster to assemble and gets lots of green points for sequestering carbon dioxide. It is also getting really popular with builders, particularly in the UK. One developer of a big project in London's Elephant and Castle describes the benefits in Building Magazine:
“We are trying to achieve the regeneration of Elephant and Castle under the ‘people, planet, profit’ banner,” explains [project manager] Mittermaier. “Compared with concrete or steel, the environmental benefits are hundreds of times better. It is a renewable material, there is very little waste during production and it is very carbon efficient to transport. CLT allows us to achieve better fabric efficiency as the panels fit together so precisely, which saves money on the heating system,” he says. “There are dramatic programme benefits and it is much safer to erect.”
The first building in the project took only 8 workers to construct, compared to 60 or 70 if built in concrete. It took 12 weeks instead of 20. However, the panels are still expensive, compared to concrete.
In terms of the bottom line Mittermaier says that CLT is more expensive than concrete or steel but this is balanced out by the programme savings. “At the moment we have rough cost parity with [concrete and steel],” he says. “When we are building thousands of units the costs should come down.”
Hawkins\Brown's 10 storey wood tower
Also on the rise is what is called the tallest timber tower in Europe, a very high end building on Regent's Canal by Hawkins\Brown. It's pretty jazzy, with " a unique cruciform plan which not only gives the development a unique residential experience, but results in a dynamic form when seen from the Regent’s Canal." All the apartments have two or three aspects with big terraces.
In the UK at least, CLT is being used for all kinds of low and midrise buildings. As codes get changed in North America to permit higher wood structures and CLT plants continue to get built, we will probably see much of the same happen here.
There is an almost endless supply of pine-beetle damaged wood available right now in North America; they should be cranking this stuff out like toothpaste.