Engineered wood isn’t a phrase that springs to mind when speaking of Manhattan real-estate projects. But a local partnership wants to change that, and the federal government hopes it succeeds. Source: The Wall Street Journal
130 134 Holdings LLC, in partnership with Spiritos Properties, SHoP Architects, Arup, Icor Associates and environmental consultancy Atelier Ten, is developing plans for a high-rise residential building at 475 W. 18th St. that would be constructed entirely of wood.
The project is one of two that the US Department of Agriculture, in partnership with two industry groups, the Softwood Lumber Board and the Binational Softwood Lumber Council, is to announce as winners of the first US Tall Wood Building Prize Competition.
The two winners – the other is a 12-story project in Portland will split a US$3 million prize intended partly to fund research into the use of engineered wood, or man-made composites, in high-rise construction.
A city noted for soaring towers of glass and steel might seem to have little place for a preindustrial building material. But wood proponents say it’s ideal for an urbanizing population, where the challenge is to accommodate ever-denser cities while reducing the carbon footprint of concrete, steel and other conventional building materials.
What’s more, they say, the material being used for tall-wood structures today bears little resemblance to the lumber in your great-grandfather’s barn.
Architects and builders now work in the realm of “mass timber,” a form of construction that uses large, prefabricated wood elements.
“The science of wood construction has come a long way in the past several decades,” said Chris Sharples, a principal at SHoP, which is leading the design of 475 West 18th.
With high-tech products such as cross-laminated timber, “every element of the building, right down to the elevator core, can be constructed in wood.”
While displacing conventional construction materials would please the lumber industry, which provided $2 million of the prize – it would also yield environmental benefits, say backers of wood construction.
“There’s a lot of carbon emissions associated with the production of steel and concrete,” said Vishaan Chakrabarti, also a SHoP principal. “Wood is exactly the opposite.”
Aesthetics are another avenue of promotion. While most modern buildings attempt to hide their structural, loadbearing elements, wood “is structure people are going to want to touch and feel,” said Mr Chakrabarti.
A large wood beam in an apartment would be a mark of authenticity, he said, much like the exposed beams and irregular floorboards that people show off in renovated loft spaces.
For city residents, the benefits might be more prosaic. Since most mass-timber elements are fabricated before they reach the building site, there’s less pouring of concrete, bending of rebar and so forth.
“Basically you’re working with a bunch of carpenters and an erector,” said Mr Sharples.
To be sure, even champions of tall-wood building (defined as 80 feet or higher) concede its limits.
One is height. Tall-wood structures in Europe and Canada, considered the leader in the field, tend to average 10 or so stories, though there are taller structures and dreams of going higher still.
That could be critical if wood construction is to gain greater acceptance in New York, where real-estate economics demand extreme heights on relatively small lots.
Mr Chakrabarti is optimistic that innovation will conquer the height constraint. Much of it will have to do with improved “moment connections”—where beams meet columns.
The higher the structure, the more critical these become in handling wind and seismic activity.
Fire concerns could be another barrier to acceptance. Yet wood proponents say modern wood products aren’t as hazardous as they might seem to the layman.
“It’s important to understand that these are not ordinary two-by-fours,” said Mr Chakrabarti. “This is a very special classification of wood in terms of its density.”
David Farnsworth, a structural engineer at global consulting firm Arup, said it’s a bit like throwing a huge log on a fire: The outside will burn first, forming what engineers call a “char layer,” but the inside will survive far longer.
“When steel heats up, it softens and sags quite significantly,” said Mr Farnsworth, “whereas timber actually performs better. It doesn’t lose as much of its stiffness. It’s counterintuitive.”
In any event, 475 West 18th will be subject to the same building-department scrutiny as any other project.
“It has to be tested and it has to be proven,” said Mr Chakrabarti. “That’s really a huge part of why this competition was launched, to allow firms like ours to be able to do the R&D to prove it to ourselves and prove it to the building department.”
