Tall timber not ready for prime time

It has been a tough summer for advocates of combustible materials-rich construction methods that stretch the limits of relaxed building codes and are pitched as environmentally friendly alternatives to concrete or steel.

A charade bolstered by a 2015 U.S. Department of Agriculture program appeared to run its course last month in Portland, Ore. Proponents of Framework, a 12-story residential and commercial structure designed with cross laminated timber (CLT) load-bearing members, placed their project on hold. A development, design and construction team cited “changing market conditions over the past two years including inflation, escalating construction costs, and fluctuations in the tax credit market.”

Framework stakeholders had secured state and city permits for what they packaged as the first U.S. timber high rise. Project prospects climbed three years ago with a $1.5 million Tall Wood Building Prize in a USDA and Softwood Lumber Board competition. It supported what the team called “a rigorous, two-year research & development phase and performance-based review process. The result was global breakthroughs in structural, fire, and acoustical performance testing that proved tall mass timber buildings can comply with U.S. building code and paved the way for mass timber construction across the country.”

The Framework decision followed abandonment of efforts to build the second 2015 Tall Wood Building Prize subject, 475 West 18th, a 10-level New York City residential development designed with emphasis on load-bearing wood members. The 475 West 18th and Framework outcomes have not deterred the USDA from pursuing additional Tall Wood Building competitions, although concrete industry stakeholders have pushed back on agency attempts to budget for any program promoting one building material at the expense of competitors.

The CLT assemblies for the Portland and New York tower concepts differ significantly in load-bearing potential from the standard wood 2 x 4s that builders and developers are increasingly using for three- to five-story residential and commercial developments. But no amount of industry promotion, engineering and technical support, or environmental spin will relieve CLT of the combustibility traits inherent in 2 x 4s or any established wood product.

Wood-fueled fires burn building occupants, their possessions and, in some instances, first responders and neighboring properties. The list of parties at risk in the face of cheap wood construction is even longer. In a new cost-benefit analysis centered on Los Angeles County, Columbia University Adjunct Assistant Professor Urvashi Kaul calculates wood-framed residential building fires’ economic impact on citizens and local governments. Over the next 15 years, he concludes, Los Angeles could incur more than $22 billion in wood-framed residential fire losses. Beyond roughly $20.5 billion in property damage, city expenditures could exceed $132 million—factoring direct police, fire and sanitation department costs, plus indirect remediation, insurance and planning costs.

Professor Kaul analyzes the 2011 Renaissance City Center and 2014 Da Vinci Apartment fires in the Los Angeles area. The former destroyed five buildings, required 100 firefighters to extinguish, and displaced 100-plus senior citizens and other residents from nearby homes. Fire consumed the Da Vinci property, damaged four neighboring buildings, required mobilization of 250 firefighters, and prompted shutdown of the California Highway 101 northbound lanes.

A familiar source for this column, the Build With Strength coalition, highlighted the cost-benefit study findings as part of its national campaign to strengthen building codes. Officials responsible for adopting codes and setting state or municipal budgets can fulfill their duties to building occupants, first responders and taxpayers by questioning any one peddling combustible materials to bear loads in bigger, taller buildings. Professor Kaul has run the numbers.