Cross Laminated Timber: Wood Innovation for the Future

Cross Laminated Timber, or CLT, is quickly gaining recognition as an innovative material that presents an opportunity to construct sustainable, cost effective structures in condensed time periods using wood as the primary building material. As one of an emerging set of mass timber products, the topic is popping up at countless architecture and wood products industry meetings and events across the country and generating an exciting buzz among suppliers and manufacturers alike.

CLT is a manufactured timber product using dimensional lumber to construct panels between three and seven layers thick. Prefabricated off site, panels are press-glued together and are able to be easily cut to size and be customized for mechanical and electrical systems. Because panels are relatively light and easy to attach, they are quick to assemble once they reach the building site.

CLT can be used as a sole building material or can be used in conjunction with steel or concrete to create “hybrid” CLT buildings. And although CLT is primarily made of softwood in the U.S., there are opportunities for hardwood. Europe has already embraced hardwood CLT for use in numerous projects around the continent and as products are developed and pass testing requirements in the U.S., more hardwood could potentially be incorporated into the mix of available products.

Although the future of CLT, both softwood and hardwood, looks promising, there are barriers that must first be overcome before it becomes a widely accepted construction material. Currently CLT buildings in the U.S. are limited to six stories; any higher than 85 feet requires additional testing, peer review, and specific project approval. However, the International Code Council, developer of model building codes in the U.S., is considering amendments this year that would give approval for eighteen story CLT buildings in the 2021 International Building Code.

Assistance from all members of the wood products industry, including the hardwood sector, is needed to effect changes to the building code…changes that will encourage the continued development of CLT products using both softwood and hardwood.

How can you be helpful?

Outreach to and engagement with those building officials that will vote on final proposals to the existing codes are crucial to success. There are more than 8,000 governmental jurisdictions across the country. Each jurisdiction is permitted from 4 to 12 voting representatives based on population served. Communicating the importance of expanding CLT’s role in future construction projects to enough voters will be a challenge, and you can help.

Key points to communicate to voters include the following:

  1. Tall wood buildings have an established track record. Recent buildings in the United Kingdom, Norway, British Columbia, Minneapolis and Portland have provided real-world examples of how mass timber works in tall buildings. Learn more at
  2. The International Code Council (ICC) Ad Hoc Committee on Tall Wood Buildings, comprised of engineers, architects, building and fire officials, and other representatives, has spent the last two years carefully studying the science of tall wood buildings. The Committee has proposed a series of 14 code changes to allow up to 18 stories of tall wood construction.
  3. Mass timber has inherent fire resistance. Successful ASTM E119 fire endurance testing led ICC to first recognize CLT in the 2015 International Building Code.  2-hour fire endurance was required by code, but actual fire testing demonstrated endurance of 3 hours and 6 minutes. Additional fire testing specified by the ICC Ad Hoc Committee further validated the fire performance of mass timber.
  4. Among the other benefits of mass timber, include:
    1. The resilience of mass timber panels offers the strength of steel at lower weight;
    2. Mass timber is a renewable resource that sequesters greenhouse gasses and is manufactured at much lower energy intensity, and substitutes for carbon-intensive fossil-fuel based alternatives;
    3. Mass timber panels can be installed more easily, in less time, and at lower cost than other materials; and
    4. The design flexibility and energy efficiency afforded by mass timber panels offer opportunities to create more attractive built environments.

Encourage Eligible Voters to Register by March 16

Eligible voters in the ICC process are public officials or qualified government agencies, defined as “governmental units, departments or agencies engaged in the administration, formulation, implementation or enforcement of laws, ordinances, rule or regulations relating to the public health, safety and welfare.” That definition includes housing bureaus, energy code enforcers, building code departments, fire bureaus and many more. Each agency can receive a number of votes proportionate to the total population it serves:

0 – 50,000 = 4 votes
50,001- 150,000 = 8 votes
Over 150,000 = 12 votes

If you know or work with those you believe to be eligible voters, please reach out to them and encourage them to vote.  If their agency is not yet registered to vote, they may do so by joining the ICC by March 16, 2018 at  Agencies will then have until September 23 to designate their voting representatives. Membership fees range from $135 to $370, depending on the jurisdiction’s population, and covers an entire agency. Each individual does not need to pay the registration fee.

By pulling together as an industry, we can ensure that this new and innovative product has a path towards acceptance and use throughout the country…and a path towards including hardwood can be clarified and pursued.

Dana Cole is Executive Director at the Hardwood Federation, a Washington D.C.-based hardwood industry trade association that represents thousands of hardwood businesses in every state in the U.S. and acts as the industry’s advocacy voice on Capitol Hill. She can be reached at

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