Building Fast, Building Green with CLT

Researchers at the Forest Products Laboratory (FPL) and around the world have been exploring cross-laminated timber (CLT) as a greener alternative to traditional building materials like concrete and steel.

CLT concept.

CLT is constructed of lumber stacked in alternating directions, glued, and pressed to form rectangular panels.

A new brochure from USDA, Cross-Laminated Timber and Green Building, provides a quick look at the benefits of CLT and highlights two construction projects as case studies.

Construction on Framework, a groundbreaking high rise residential building in Portland, Oregon, began in 2015.  The building, primarily constructed of CLT, received $1.5 million in funding from USDA, the Softwood Lumber Board, and the Binational Softwood Lumber Council.

In the United Kingdom, CLT was featured in the construction of Stadthaus at Murray Grove in London.  The high-rise apartment building was known as the tallest modern wood structure when it was completed in 2009.

Because CLT is a pre-fabricated material that is custom cut to a specific design, builders simply fasten and assemble the panels once they reach the construction site.  As a result, CLT reduces building time and onsite waste.  By using CLT, builders can cut down on economic and environmental costs, without sacrificing beauty, versatility, or performance.

Blog post by Francesca Yracheta

Building a Case for Building with Wood

Brittany Patterson, an E&E (energy and environment) reporter for ClimateWire, recently visited the Forest Products Laboratory (FPL) to learn all she could about cross-laminated timber (CLT) and building tall with wood.

The University of British Columbia's Earth Sciences Building in Vancouver is made of wood.  (Photo courtesy of FTP Edelman.)

The University of British Columbia’s Earth Sciences Building in Vancouver is made of wood. (Photo courtesy of FTP Edelman.)

After a day at the Lab and talks and visits with others working with CLT, Brittany amassed enough information to author a comprehensive article on the current state, and future promise, of building mid- to high-rise buildings with wood in the United States.

The article, titled Saving America’s Forests One Wooden High-Rise at a Time, touches on many of the important issues that make CLT attractive to FPL and the U.S. Forest service: forest restoration, carbon sequestration, and bolstering rural forest-based economies.

It also summarizes much of the research that FPL and others are doing to bring wood into building codes and standards that would greatly expand it’s use.

Many thanks to Brittany for visiting the Lab, and for helping educate the public about the  benefits of wood construction!

Portland Awaits Mass Timber Conference : March 22-24, 2016

MTC Logo Horizontal DateThe Forest Products Laboratory (FPL) is proud to sponsor Forest Business Network’s North American Mass Timber Conference, March 22–24, 2016, in Portland, Oregon. The event, held at the Portland Marriott Downtown Waterfront, will allow industry professionals a forum to discuss the future of timber construction in North America.

Registration is open, and event organizers are offering a 25% “early bird” discount on full passes and exhibit spaces through December 2.

The conference will feature a lineup of expert speakers from around the world who will address how to best advance wood as a building material, improve the cross-laminated timber (CLT) and mass timber industries in North America, and increase the use of wood in low- to mid-rise and tall buildings.

The conference will also explore current opportunities and obstacles for nail-laminated timber, glulam panels, and laminated veneer lumber.

In-depth panels will tackle topics from 9 categories, including:

Overall Building System

  • Mass timber overview and standards
  • PRG-320 ANSI/APA Performance Standard (CLT), fasteners

U.S. Building Codes

  • Fire resistance, seismic, acoustic, thermal values, health benefits
  • Legal/liability/insurance

Manufacturing of Cross-Laminated Timber (CLT)

  • Efficient plant design, layout/operation, and workforce
  • Current and anticipated manufacturing capacity in North America
  • Design and software, CAD programming

Engineering — Challenges and Opportunities

  • Mass timber as a construction product in North America
  • Research gaps


  • Economic efficiencies
  • Sourcing contractors for building mass timber buildings

Nail-Lam and Other Mass Timber Construction Products

  • Current mass timber buildings
  • Nail-lam and CLT

U.S. Market

  • Current mass timber buildings and what they cost
  • Geographic opportunities/limitations

International Market

  • Update on mass timber construction in Europe and beyond

A&Es, Designers, City Planners, Building Department Officials

  • Compatible software and the transfer of design into finished products
  • Concrete and wood working as one

Timber construction is on the rise in North America — don’t miss out on this exciting opportunity! Join FPL at the North American Mass Timber Conference!

For more information, including the most up-to-date agenda, please visit

Mass Timber Research Workshop Held at FPL

The Forest Products Laboratory (FPL) hosted the inaugural Mass Timber Research Workshop this week in cooperation with Woodworks – Wood Products Council.  During the two-day event, more than 120 national and international attendees, including 26 presenters, gathered to learn about cross laminated timber (CLT) and how its design and use can further green building efforts while also aiding in forest restoration activities. Tom Williamson of Timber Engineering, LLC, facilitated the workshop, and the Softwood Lumber Board generously provided support.

CLT offers outstanding structural, thermal, and acoustic performance.

CLT offers outstanding structural, thermal, and acoustic performance.

Experts discussed past and current research on CLT and how the material can be used in conjunction with underutilized and high-quality wood to construct a variety of multi-story buildings.  While CLT has been used in Europe for nearly 20 years, it is only recently catching on in North America.  Multi-story buildings using CLT are popping up around the United States and Canada, and in fact, the first large-scale commercial installation of CLT in the United States (using CLT manufactured in North America) was built right here in Madison, Wis., for Promega Corporation.  Construction is slated to begin shortly on what will be the tallest wood building in North America, a 12-story residential structure in Quebec City, Quebec.

In addition to CLT construction and design, other topics discussed at the workshop included information on fire safety, seismic conditions, architectural design, and the Forest Service budget outlook for 2016 and beyond. According to FPL Assistant Director for Wood Products Research Mike Ritter, the Forest Service firefighting budget is expected to continue to increase in the years ahead, making CLTs and other value-added wood products a critical component in maintaining the health of our Nation’s forests.

Contributed by Steve Schmieding and Francesca Yracheta

Solid Research on Shaky Science: Building with Wood in Earthquake-Prone Regions

Nepal 2015—Japan 2011—Chile 2010.

In the past decade, these nations, and many others, have been host to some of the most destructive earthquakes in recent memory. Along with the inestimable human and emotional toll these events take on communities around the globe, the costs associated with reconstruction efforts are equally astronomical, often edging into the billions of dollars. Although we can’t effectively predict or stop earthquakes from occurring, we can be ready, and minimize the impacts of these damaging seismic events.

CLT concept and use in a nine-story mid-rise building in London.

CLT concept and use in a nine-story mid-rise building in London.

From relatively stable ground in Madison, Wisconsin, researchers at the Forest Products Laboratory (FPL) are searching for better ways to build more resilient, taller, safer, and cost effective wooden structures for use in earthquake-prone areas of the nation. For the wood building community, the most viable tall building construction solution incorporates the use of cross-laminated timber (CLT).

A CLT panel consists of multiple layers of kiln-dried lumber boards stacked in alternating directions, and bonded together with structural adhesives. The end result is an inexpensive, strong, solid, rectangular panel that can be used for building walls, floors or roofs.

CLT has already established itself as an important building material in Europe, but is relatively new to North America. Wooden buildings over eight stories tall, which incorporate CLT into their design, have sprung up in areas of low seismic activity to include Sweden, Australia, and the United Kingdom. Experts believe that CLT could also be a cost-effective and environmentally friendly alternative to traditional construction materials for buildings up to 125 feet tall.

FPL, along with the Coalition for Advanced Wood Structures, is developing seismic design perimeters for CLT use that will meet or exceed both design and safety codes. The team hopes that the project will lead to the development of a performance-based seismic design (PBSD) methodology to investigate the feasibility of three prototype systems. This PBSD would allow for the construction of buildings in earthquake-prone areas up to 14 stories tall using CLT components.

Researchers believe that this project will lay the ground work for buildings with elongated natural periods, near elastic behavior, and an increased resiliency to the high forces and accelerations of seismic events.

The growing trend of urbanization has increased the need for taller buildings across the country, including in areas that are crisscrossed by tectonic boundaries like California’s San Andreas Fault or the Cascadia Subduction Zone of the Pacific Northwest. At the same time, more emphasis has been placed on environmentally and fiscally responsible construction. Properly rated CLT construction holds great potential for cities like Los Angeles or Seatte—urban areas that have already witnessed tragedy in the past, but hopefully, when and if the next disaster occurs, can be headline-making cities for their successful implementation of safer building techniques.

For more information on, see this Research In Progress report.