Dive Brief:

• Real estate developer Hines has released new details about a proposed mass timber office building on Chicago's Goose Island, according to Curbed Chicago.
• The six-story, 270,000-square-foot structure would be 50,000 square feet larger than the company's other modern all-wood project in Minneapolis, currently the largest structure of its kind in the U.S. Designers said despite the project's all-wood composition, mass timber would only "char" in a fire.
• Like its Minneapolis project, Hines said it would also brand the Goose Island project with the T3 (Timber, Technology and Transit) moniker, and is already considering similar projects in Atlanta and elsewhere in the country. The project still must obtain city approval, but would be part of a larger rezoning initiative to bring non-industrial development to the area.

Dive Insight:

One advantage of using mass timber is that the material's properties lend it to a speedier construction process.

On Hines' T3 project in Minneapolis, crews were able to frame 180,000 square feet in just over nine weeks at a rate of 30,000 square feet of floor space per week. The Type IV Heavy Timber-classified wood, made mostly from trees killed by the mountain pine beetle, was part of a grid-based framing system that used a mix of spruce-pine-fir nail-laminated timber (NLT) panels, spruce glulam and concrete.

Despite designers' assurance that mass timber doesn't burn like other wood, fire is always a concern when it comes to wooden structures.

In 2016, Sandy Springs, GA, officials changed the city's building codes to ban the use of wood in multifamily buildings more than three stories high and larger than 100,000 square feet. Steel advocates told Construction Dive last year that Sandy Springs was setting an example for the rest of the country with its decision to opt for strong, noncombustible materials. But the pro-wood industry maintains that if builders follow code requirements, like proper placement and installation of fire sprinklers, wood is just as safe as any other material and, potentially, even more durable.

A study commissioned by the National Ready Mixed Concrete Association found that builders' risk and commercial property insurance policies were less expensive for concrete buildings than those made of wood. The study, which used hypothetical structures as the basis for collecting insurance premium estimates, reported that builder's risk insurance was up to 72% less expensive for concrete buildings and commercial property insurance was as much as 65% less.