Adhesives, Dowels & Veneers: The Industrial Choices Shaping Mass Timber

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Mass timber has quickly become one of the most talked about building materials in the climate conversation, and for good reason. It locks away carbon from forests, displaces steel and concrete in construction, and lends itself to faster, modular assembly. But as with all industrial products, the devil is in the details. How you slice, peel, glue, or join the wood makes as much difference as the choice of species or the thickness of the panels. The production technologies behind cross laminated timber and other mass timber products are now diverging into distinct paths, each with different strengths and weaknesses. The choice of method will shape costs, carbon balances, and the kinds of buildings that can be delivered.

This is another article in my series examining the role of mass timber in Canada’s housing and climate future. The first piece laid out Canada’s timber moment, framing CLT and modular construction as the fastest lever for addressing housing shortages, jobs, and embodied carbon. The second explored how Mark Carney’s housing initiative could industrialize the sector through pre-approved designs, offtake contracts, and regional factories. The third explored the requirement for vertical integration within the industry to maximize efficiencies. The fourth showed how CLT displacement could bend the demand curves for cement and steel, making their decarbonization pathways more realistic. The fifth demonstrated that from harvest to housing, CLT already locks away more carbon than it emits, strengthening its climate case. The sixth turned to the forestry supply chain, arguing that electrification of harvesting, transport, and processing is essential to maintaining CLT’s carbon advantage. The seventh piece addressed systemic barriers, focusing on high insurance costs and bespoke code approvals, and argued that normalizing mass timber in regulatory and financial frameworks is the key to scaling. As the series progressed, a topic that came up a few times related to the different technologies involved in variants of mass timber, hence this latest piece.

The traditional approach starts with milling logs into dimensional lumber. Boards are dried, planed, and glued into perpendicular layers that form cross laminated timber. This is familiar territory for the sawmill industry, which has been cutting, drying, and shipping lumber for centuries. The advantage is that it fits into existing infrastructure and labor practices. Regional sawmills can supply laminates for local cross-laminated timber (CLT) plants without massive new investments. But the waste streams are significant. Sawing generates kerf losses, knots and defects limit yields, and not every log can be cut into ideal laminates. It is a proven but relatively inefficient system.

On the other end of the spectrum are veneer and rotary shaving processes. Here, instead of slicing logs into boards, the logs are spun against a blade that peels them into long, thin sheets or strips. These sheets become the feedstock for laminated veneer lumber or can be pressed into hybrid CLT panels. Because the entire log can be peeled, the utilization rate is higher and the resulting laminates have consistent mechanical properties. That uniformity is valuable when trying to standardize structural performance at scale. The drawback is that veneer-based production requires specialized, capital-intensive equipment. Plants need to be large, highly automated, and supplied with consistent log quality. The payoff is fewer offcuts and lower raw material costs per ton of finished product, but the barrier to entry is higher.

Beyond those two main methods, a number of hybrid and experimental approaches are emerging. Some producers are blending veneer and sawn lumber layers to create panels with predictable strength and lower waste. Others are experimenting with oriented strand and parallel strand products, which compress long strands of wood into dense, structural elements. Robotics and automated milling systems are entering the mix, cutting custom laminates with less labor and less waste. These methods are still evolving, but they point toward an industrial future for timber that looks more like auto manufacturing than artisanal carpentry.

One of the debates in the sector is whether mass timber should rely primarily on adhesives or mechanical fasteners. Adhesive-based products, like CLT and laminated veneer lumber (LVL), dominate the market today. They offer high strength, predictable performance, and well-established testing standards. The adhesives themselves are not without challenges. They add embodied carbon, some rely on petrochemical inputs, and once cured they make recycling more difficult. There is also the matter of off-gassing, although modern formulations are far safer than earlier versions.

On the other side are dowel laminated and screw laminated systems. These use hardwood dowels or long screws driven through layers of softwood to bind panels mechanically. The appeal is clear. No adhesives means a cleaner bill of materials, easier disassembly, and potentially more circular reuse. But the trade-offs are real. Mechanical systems are typically weaker, require thicker panels to achieve the same load bearing capacity, and are less standardized in codes and supply chains. Adhesives deliver efficiency and scale, while dowels and screws offer ecological simplicity and deconstruction potential. Both will find niches, but it is unlikely that mechanical fasteners will displace adhesives in the mainstream anytime soon.

One promising avenue of research in mass timber is the development of lignin-based adhesives as a replacement for petrochemical resins. Lignin is a natural polymer that makes up about a quarter of wood’s mass and is currently treated mostly as a low-value byproduct of the pulp and paper industry, often burned for process heat. By converting it into an adhesive, researchers aim to close the loop in timber production, turning waste into a high-value input while reducing reliance on fossil-derived chemicals. Early trials show that lignin-derived adhesives can deliver comparable bonding strength and durability to conventional phenol-formaldehyde or polyurethane systems, though consistency and scalability remain challenges. If these hurdles are overcome, lignin-based resins could lower the embodied carbon of mass timber even further and support a fully bio-based materials cycle where the building sector captures more of the value chain from the forests it depends on.

Comparing these approaches side by side highlights that there is no single correct answer. Milling sawn lumber for laminates makes sense for distributed, regional plants near housing markets that need quick output and where sawmill capacity already exists. Veneer and rotary peeling processes are better suited for industrial hubs designed to pump out massive volumes of standardized material. Adhesive bonding supports global supply chains and tall timber towers, while dowel based systems may appeal to boutique builders and markets with stricter ecological preferences. In every case, the choice has implications for waste streams, energy use, labor requirements, and long term carbon accounting.

The language around mass timber can be confusing, with several terms often used interchangeably when they actually describe different products. That’s something I’ve been guilty of in this series, using CLT as the generic term instead of mass timber. CLT refers to large panels made by gluing layers of boards at right angles, giving strength in both directions and making it the most common product for walls and floors. Glulam, or glued laminated timber, is made from long boards laminated parallel to one another, creating strong beams and columns. LVL uses thin sheets peeled from logs and pressed together with the grain aligned, offering consistency and high strength for structural members. Parallel strand lumber and oriented strand lumber compress long strands into dense, engineered elements. Dowel laminated timber and nail laminated timber are alternatives that rely on mechanical fasteners rather than adhesives. While all fall under the umbrella of mass timber, their applications differ: CLT for panels, glulam for framing, LVL for structural uniformity, and dowel or nail laminated products for lower-carbon or easily disassembled designs.

For Canada, this technology debate is not academic. With Mark Carney’s housing plan and pressure to cut embodied carbon, the country must decide whether to double down on conventional CLT based on dimensional lumber or make the leap to veneer-driven plants that look more like plywood factories scaled up for housing. There is also the question of whether policy should encourage mechanical joining systems for disassembly or stick with adhesives for speed and strength. Each pathway shapes not only domestic housing delivery but also Canada’s chance at becoming an exporter of timber products. The decision is not just about logs and glue. It is about industrial strategy, climate credibility, and whether Canada wants to lead in a material that could redefine global construction.

Mass timber’s appeal is simple. It turns trees into carbon-storing buildings that rise faster and cleaner than their concrete cousins. But the technology behind it is anything but simple. Milling versus peeling, adhesive versus dowel, distributed mills versus centralized factories. Each choice determines whether the sector grows in fits and starts or scales up to meet the real demands of housing, jobs, and climate action. The future of mass timber will be written not just by architects but by the engineers, mill operators, and policymakers who decide how those laminates are made.