CLT (Cross-Laminated Timber)
CLT is a mass timber panel system made from layers of solid lumber glued together at right angles, producing large, strong, dimensionally stable panels that function as structural walls, floors, and roofs. The visible wood surface on both faces makes CLT both a building system and a finish material. SENTIENT works with CLT in architectural installations where exposed timber is part of the design language.
Composition
CLT panels are built from kiln-dried lumber boards stacked in alternating perpendicular layers, typically three, five, or seven plies deep. Each layer’s grain runs at 90 degrees to the layers above and below, and the boards are bonded with structural polyurethane or melamine adhesive under hydraulic pressure. North American CLT typically uses softwood species with a specific gravity above 0.35, kiln-dried to approximately 12% moisture content. The cross-lamination is what gives CLT its bidirectional strength and dimensional stability.
Characteristics
CLT’s cross-laminated structure provides strength and stiffness in both directions, unlike conventional lumber or LVL where grain runs one way. The panels are manufactured in large formats, often up to 3 meters wide and over 18 meters long, allowing them to replace entire wall and floor assemblies in a single piece. Fire performance is a standout property: CLT chars slowly and predictably, maintaining structural capacity behind the char layer. In testing, a five-ply CLT wall with gypsum wallboard achieved over three hours of fire resistance. Seismic performance is also strong, with a seven-story CLT building tested on a shake table showing no residual deformation under a magnitude 7.2 earthquake simulation.
Common Uses
CLT serves as structural walls, floors, and roofs in mass timber construction, from mid-rise residential buildings to commercial offices and institutional projects. Architects also specify it for exposed ceiling panels, feature walls, room dividers, and large-format design elements where the visible wood surface is the finished interior. The material has become central to the mass timber movement, offering a renewable structural system that stores carbon and reduces construction waste compared to steel and concrete.
We work with CLT in architectural installations and large-scale millwork projects where the exposed timber panel is both structural and decorative. The visible wood surface reads as honest material, and we treat it with finishes that protect the face while preserving the cross-laminated grain pattern that makes CLT distinctive.
Limitations
CLT requires specialized fabrication equipment and CNC processing for precision cuts, connections, and openings. Engineering the connections between panels adds design complexity compared to conventional framing. Material cost is higher than standard wood framing, though faster installation can offset the difference on the job site. Moisture management during construction and throughout the building’s life is essential because prolonged exposure to water degrades adhesive bonds and promotes decay. CLT is not a material you order off the shelf. Lead times and coordination with the fabricator are part of every project.
Finish Compatibility
CLT’s wood surface accepts clear oil, water-based polyurethane, and stain readily. Many projects leave the timber with a light clear seal or natural oil finish to showcase the cross-laminated pattern and let the wood age with character. For high-traffic or commercial installations, a harder film-forming finish provides better protection against scuffs and wear. Painted CLT is less common because the appeal of the material is its visible wood surface, but it takes paint well when the design calls for a solid color.
Related Materials
LVL (Laminated Veneer Lumber)
Consistent structural beams for oversized tables and built-in support.
OSB (Oriented Strand Board)
Structural panels for concealed backing and large-scale installations.
MDF (Medium-Density Fiberboard)
Smooth, uniform panels for painted furniture and lacquered millwork.
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