Cross-Laminated Timber Manufacturing Expands Across the United States

Cross-laminated timber, commonly known as CLT, is reshaping how residential and commercial builders approach structural framing in the United States. This engineered wood product, made by stacking and gluing layers of lumber at perpendicular angles, offers strength comparable to concrete and steel while providing a renewable alternative to traditional building materials. With new domestic manufacturing facilities coming online and updated certification standards paving the way for broader adoption, CLT is transitioning from a niche product to a mainstream construction option. Builders and architects looking for sustainable building material alternatives are taking notice as more cross-laminated timber is now made in the US, reducing reliance on imports and opening new design possibilities. Understanding the properties, applications, and procurement landscape of CLT is essential for any construction professional evaluating modern framing strategies.

Domestic CLT Manufacturing Expands Across the United States

For years, the North American CLT market relied heavily on a single domestic producer, Montana-based Smartlam, supplemented by imports from Europe. That landscape has shifted dramatically as new facilities have opened and existing lumber producers have retooled their operations to manufacture cross-laminated timber. This expansion addresses both supply chain resilience and the growing demand from architects specifying mass timber in their projects.

New Production Facilities Enter the Market

D.R. Johnson, a family-owned forest products company in Riddle, Oregon, became one of the first U.S. manufacturers to receive certification under the new American National Standards Institute (ANSI) standard for CLT production. Using locally sourced Douglas fir, the company now produces 3-layer, 5-layer, and 7-layer CLT panels for the domestic market. This certification represented a milestone because it validated that U.S.-made CLT meets the same performance criteria as imported panels, giving specifiers confidence in domestic sourcing.

Other manufacturers have followed suit. In the Pacific Northwest, where the confluence of timber resources and progressive building codes creates favorable conditions, several facilities now produce CLT at commercial scale. The Southeast has also emerged as a manufacturing hub, with companies leveraging the region’s abundant Southern yellow pine to produce panels optimized for structural applications. This geographic diversity means builders in different regions can source CLT locally, reducing transportation costs and lead times.

Certification Pathways and Quality Standards

The ANSI/APA PRG 320 standard serves as the benchmark for CLT manufacturing in North America. This standard establishes requirements for:

• Raw material grading and moisture content specifications
• Lamination adhesive performance and durability testing
• Panel dimensional tolerances and layup configurations
• Structural capacity verification through third-party testing
• Quality control protocols for ongoing production monitoring

Manufacturers seeking certification must undergo an initial plant audit followed by periodic inspections to maintain compliance. This rigorous framework ensures that CLT panels from different producers deliver consistent performance, which is critical for engineers who rely on published design values when calculating structural loads.

Supply Chain Implications for Builders

The growth in domestic CLT production has significant implications for builders planning mass timber projects. Shorter shipping distances translate to lower carbon footprints and reduced freight costs. Domestic sourcing also simplifies coordination because manufacturers operate within the same regulatory environment and building code framework as project teams. Evaluating building product manufacturers on quality and service remains critical even when sourcing domestically, as warranty support and technical assistance vary across suppliers.

Structural Performance and Design Flexibility with CLT

Cross-laminated timber offers engineers and architects a unique combination of structural capacity and design freedom. The cross-lamination process creates panels that resist forces in multiple directions, making them suitable for wall, floor, and roof assemblies in buildings up to 18 stories under current code provisions.

Load-Bearing Capabilities and Span Performance

A standard 5-layer CLT panel, typically 6.75 inches thick, can span up to 20 feet in floor applications while supporting residential live loads. This span capability reduces the need for intermediate beams and columns, creating open floor plans that are difficult to achieve with traditional stick framing. For wall applications, CLT panels provide both structural support and an air barrier, simplifying the enclosure assembly.

Engineered wood products like CLT offer predictable performance because the manufacturing process removes natural defects such as knots and splits that can create weak points in sawn lumber. Each panel is computer-modeled and fabricated to precise dimensions, with openings for doors, windows, and mechanical penetrations cut at the factory using CNC equipment. This precision reduces field waste and speeds up installation.

Seismic and Wind Resistance

One of the most compelling attributes of CLT construction is its performance under seismic loading. The panels are lighter than concrete or masonry, which reduces the inertial forces that a building must resist during an earthquake. At the same time, the ductile connections used in CLT assemblies allow the structure to dissipate energy through controlled movement.

Recent shake-table testing at the University of California San Diego confirmed that a 10-story CLT building could withstand a magnitude 7.0 earthquake with minimal structural damage. For builders in seismically active regions, structural engineering strategies for resilient design support the case for CLT as a viable alternative to traditional lateral force resisting systems.

Connection Detailing Considerations

The performance of a CLT structure depends heavily on connection design. Self-tapping screws, steel brackets, and splines are common connection methods, each suited to different load paths and assembly sequences. Manufacturers typically provide connection design guidance specific to their panel systems. Builders working with CLT for the first time should invest in proper training for installation crews, as the techniques differ substantially from conventional framing.

Fire Performance and Building Code Compliance

Perceptions about fire safety have historically been a barrier to wood construction in larger buildings. However, CLT performs differently in fire conditions than light-frame wood construction because of its mass and charring behavior.

Char Layer Formation and Structural Integrity

When exposed to fire, CLT forms a protective char layer that insulates the unburned wood beneath it. This char layer retains much of its structural capacity during a fire, allowing CLT assemblies to achieve fire-resistance ratings comparable to non-combustible construction. A 5-layer CLT panel can achieve a 2-hour fire rating with properly designed gypsum board protection on the exposed face.

The 2021 International Building Code includes provisions for mass timber construction through the addition of Type IV-C, IV-B, and IV-A construction classifications. These categories correspond to increasing levels of fire protection and allow taller wood buildings than previous code editions permitted.

Sprinkler and Passive Protection Requirements

Code compliance for CLT buildings typically requires a combination of active and passive fire protection measures. Automatic sprinkler systems are mandatory for buildings exceeding certain height thresholds. Exposed wood ceilings are permitted in many occupancy types provided the panels meet char rate calculations verified through testing.

Sustainability, Cost Analysis, and Builder Adoption Strategies

The environmental case for CLT is strong, but builders must also evaluate the economic realities of adopting this material system. Understanding both the lifecycle benefits and the upfront cost structure is essential for making informed sourcing decisions.

Carbon Sequestration and Environmental Benefits

Wood is unique among structural materials because it stores carbon. A cubic meter of CLT sequesters approximately 1.1 tons of carbon dioxide, and that carbon remains locked in the building for the life of the structure. When sourced from sustainably managed forests, CLT offers carbon benefits that concrete and steel cannot match.

Manufacturing CLT also requires less energy than producing equivalent structural capacity in concrete or steel. The production process for CLT emits roughly 50 percent less greenhouse gas than reinforced concrete and 70 percent less than structural steel. For builders pursuing green building certifications such as LEED or the Living Building Challenge, these reductions contribute directly to certification points.

Cost Comparison with Conventional Systems

The material cost of CLT panels is higher per square foot than traditional framing lumber, but the installed cost can be competitive when accounting for the speed of construction and reduced labor requirements. A CLT superstructure for a mid-rise building can be erected in weeks rather than months, saving on general conditions, financing costs, and overhead.

• Material costs: CLT panels typically cost $25 to $45 per square foot delivered, depending on panel thickness and configuration
• Installation savings: A CLT shell can reduce framing labor by 30 to 40 percent compared to stick framing
• Foundation savings: Lighter structural loads reduce foundation material requirements by up to 20 percent
• Schedule compression: Faster enclosure allows interior trades to start earlier, shortening overall project duration
• Waste reduction: Factory fabrication generates 90 percent less job-site waste than conventional framing

Partnering with CLT Suppliers and Designers

Builders making the transition to CLT should engage with manufacturers early in the design process. Most CLT producers offer design-assist services that help optimize panel layouts for material efficiency and fabrication cost. These partnerships can also streamline the permitting process because manufacturers provide pre-engineered connection details and code compliance documentation.

For project teams exploring CLT for the first time, starting with a single-family residence or a small commercial building provides a manageable introduction to mass timber construction. The lessons learned on these initial projects carry forward to larger, more complex buildings. Many builders find that smart material selection practices used for CLT extend naturally to other product choices throughout the project.

Conclusion

The expansion of domestic cross-laminated timber manufacturing represents a meaningful shift in the American construction landscape. With more production facilities coming online, clearer certification standards in place, and building codes evolving to accommodate taller wood structures, CLT is positioned for sustained growth. Builders who invest in understanding this material system now will be well prepared to offer clients a structural option that combines sustainability, speed of construction, and design versatility. As the supply chain continues to mature and costs become more competitive, cross-laminated timber is moving from an emerging technology to a standard tool in the builder’s kit.