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More are warming to high-rise timber buildings

"It's incredibly beautiful," says one developer of the new engineered timber being used in place of steel today

A construction worker at one of a pair of timber office buildings in Brooklyn's Williamsburg neighbourhood developed by the firm Flank. Mass timber, an engineered product made of layers of spruce or fir pressed together, is used today instead of single trunks of timber.

New York

DEVELOPERS have not used wood for much other than houses since the horse-and-buggy days. But the knotty building material is making a comeback.

Seeking greener projects, which many consumers continue to embrace despite an anti-environmental mood in Washington, builders are choosing timber for offices, apartments and campus buildings, rather than the concrete and steel that dominated construction for decades.

Not everybody is on board with the trend, which is playing out from coast to coast in the United States.

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Concerns persist about wood's flame resistance and strength, as well as its cost, which can be 30 per cent more than traditional materials.

But proponents scored a huge win last month when the International Code Council, an influential advisory group in Washington, concluded that some wooden buildings could climb as high as 18 storeys, more than twice the current permissible height, without compromising safety.

Consumers have already shown interest. "The connections people have with wood cannot be underestimated," said Tim Gokhman, director of New Land Enterprises, which is behind two projects in Milwaukee that are mostly made of wood.

One is a seven-storey office building. The other is Ascent, a 201-unit luxury rental tower that, at 21 stories, would be the tallest timber building in the Western Hemisphere.

Both await approvals - including permission to exceed height restrictions, which developers say will not pose any danger - but expect to break ground in 2019. Unlike the production of concrete and steel, which generates huge amounts of carbon dioxide, the creation of lumber is a relatively low-pollution process, Mr Gokhman said.

Trees are also an easily renewable resource, achieving nearly their full size in a decade, according to Jason Korb, an architect and a designer of both New Land projects. He added that the US had some catching up to do, as wooden towers exist or are under way in Australia, Austria, Canada and Norway, among other countries.

"It's really starting to come into its own around the world right now," Mr Korb said. For those who expect wooden buildings to resemble log cabins, the current crop may come as a surprise.

Most have metal or brick facades, a stipulation of building codes focused on fire restrictions, which means the buildings often do not stand out from the outside. Inside, though, gently striated lumber surfaces are on full display, as they are at Carbon12, an eight-storey, 14-unit condominium in Portland, Oregon, currently the country's tallest wood structure.

In fact, there is so much exposed and unpainted wood, in columns, beams and ceilings, it gives the condos the appearance of a construction zone.

Half the condos, which range from US$800,000 to US$1.3 million, have sold since the building opened last spring, said Ben Kaiser, the developer. He faced challenges getting Carbon12 built. The permit process took almost two years to wind through city and state agencies, largely because wood buildings in Oregon could top out at no more than six storeys, he said.

Reviving timber industry

In the end, officials concluded that wooden high-rises could help revive Oregon's stagnant timber industry, Mr Kaiser said. In August, the state increased the height limit to 18 stories.

Carbon12's timber, however, did not come cheap, according to Mr Kaiser, whose offices were also built with timber. Indeed, at US$11 million, Carbon12 was about 20 per cent more expensive to construct than a concrete version would have been, which in some ways dictated that it be a luxury condo.

"It's like anything - the first iPhone, the first flat-screen TV," he said. "Costs are high because not enough people are doing it."

Nevertheless, he plans to use wood from now on. In addition to their green benefits, he said, wood buildings perform well in earthquakes because of their lighter weight and flexibility.

Proponents of wood must still overcome a long-standing bias. In the 1800s, fires were a scourge, prompting restrictions on wood. But steel is not infallible and can buckle in extreme heat, said John Peronto, a principal at the engineering firm Thornton Tomasetti who is involved in the two Milwaukee projects.

"But we've gotten comfortable using steel and concrete products, so the question's been, 'Why would we change?' " he said.

Still, wood is not what it used to be. The decline in old-growth forests means developers can no longer count on huge single trunks to support floors.

Instead, they rely on mass timber, an engineered product made of layers of spruce or fir pressed together in a way that is similar to plywood but with a more elegant look.

Nail-laminated timber fortifies T3, a three-year-old, seven-storey office building in Minneapolis's North Loop neighbourhood.

Eighty-two per cent of the steel-clad building, whose name is a shorthand for "timber, technology and transit," is leased to tenants such as Amazon, which occupies three floors.

Asking rents are about US$23 a square foot, said David Schreiber, a managing director at LaSalle Investment Management, the landlord.

Also leasing space there is Industrious, a coworking provider, which had to spend about 15 per cent more than usual to add conference rooms and private offices to its floor, said Jamie Hodari, a company co-founder. Industrious had to route cables to avoid damaging the wood, he said.

But the investment appears worthwhile. T3 is far more popular among workers than Industrious's other Minneapolis outpost, in a glassy modern high-rise, Mr Hodari said.

"It's almost like walking into a Swedish sauna," he said. "It's incredibly beautiful."

Contemporary finishes

Hines, the real estate investment firm that developed T3, took inspiration from a nearby office building it owns, which began life as a 19th-century warehouse.

Despite robust demand, the brick-and-timber edifice had high turnover because it lacked contemporary finishes such as soundproofing, said Steve Luthman, a Hines senior managing director. T3 kept its natural aesthetic, but Hines added touches such as airtight windows and a modern heating system.

Hines is taking T3 nationwide to cities like Atlanta, where a seven-storey, 250,000-square-foot offering, developed with Invesco Real Estate, will open in West Midtown this summer. Denver and Chicago will get similar towers, which may be less expensive to construct than their predecessors.

Wood remains expensive, but the assembly-line aspect of mass-timber production, in which factories make large panels, then assemble them on-site, saves time and labour costs. "I think it works out to about the same," Mr Luthman said.

For all the recent headway, there have been stumbles. In March, a 450kg section of floor gave way at a mass-timber building under construction at Oregon State University.

The floor was made of a relatively new product, cross-laminated timber, in which layers of wood are glued at right angles to one another. And two of the seven layers broke loose, said Steven Clark, a university spokesman. "I think it had a quieting effect on the market," he said.

Winning acceptance for mass timber seems especially challenging in New York, which appears to have lagged behind other cities in proposals. But a handful of projects are under way in Brooklyn, including a pair of office buildings in Williamsburg from the firm Flank. NYTIMES