This old building material is new again

MarketWatch – It’s been 150 years since Mrs. O’Leary’s cow earned them both a bad rap for incinerating a wood-built Chicago.

Ever since, in that city and elsewhere, concrete and steel have traditionally been used to construct commercial buildings, especially those reaching several stories high. 

Yet increasingly, cross-laminated timber (CLT) and heavy timber are gaining traction as alternative framing materials in urban environments. These materials are promoted for their cost savings and relative sustainability because managed forests can be regulated and replanted, plus manufacturing wood and building with it emits less pollution than concrete and steel.

The technology, more of a reimagining of long-ago practices, has emerged in recent years — the seven-story T3 high-rise in Minneapolis was the largest mass-timber building in the U.S. at the time of its 2016 unveiling. More recently that crown has gone to the eight-story Carbon12 project in Portland, Ore. Chicago is entertaining a proposed 80-story wood skyscraper. What is new, however, is wider U.S. building-code acceptance of wood. The 2021 International Building Code will contain even more provisions to allow for mass-timber construction of taller buildings.

“As the codes change to permit the use of wood framing in taller structures, we expect to see the use of wood increase where it is economically viable to do so—either because it is more cost-effective, or it offers a market advantage over other structural systems,” said John Sheridan, executive vice president at Chicago-based James McHugh Construction Co. 

“It requires 50% to 125% less energy to create structural materials in a wood-based building than in a steel or concrete structure,” said Sheridan. “Because of this, and depending on the structure, we can expect to see taller buildings using wood-framing systems or hybrid wood/steel/concrete systems to improve energy efficiency and reduce construction costs.”

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