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Mass timber has rapidly grow to be one of the crucial talked about constructing supplies within the local weather dialog, and for good purpose. It locks away carbon from forests, displaces metal and concrete in development, and lends itself to quicker, modular meeting. However as with all industrial merchandise, the satan is within the particulars. The way you slice, peel, glue, or be part of the wooden makes as a lot distinction as the selection of species or the thickness of the panels. The manufacturing applied sciences behind cross laminated timber and different mass timber merchandise are actually diverging into distinct paths, every with totally different strengths and weaknesses. The selection of technique will form prices, carbon balances, and the sorts of buildings that may be delivered.
That is one other article in my sequence analyzing the position of mass timber in Canada’s housing and local weather future. The first piece laid out Canada’s timber second, framing CLT and modular development because the quickest lever for addressing housing shortages, jobs, and embodied carbon. The second explored how Mark Carney’s housing initiative might industrialize the sector via pre-approved designs, offtake contracts, and regional factories. The third explored the requirement for vertical integration throughout the trade to maximise efficiencies. The fourth confirmed how CLT displacement might bend the demand curves for cement and metal, making their decarbonization pathways extra real looking. The fifth demonstrated that from harvest to housing, CLT already locks away extra carbon than it emits, strengthening its local weather case. The sixth turned to the forestry provide chain, arguing that electrification of harvesting, transport, and processing is important to sustaining CLT’s carbon benefit. The seventh piece addressed systemic limitations, specializing in excessive insurance coverage prices and bespoke code approvals, and argued that normalizing mass timber in regulatory and monetary frameworks is the important thing to scaling. Because the sequence progressed, a subject that got here up a number of instances associated to the totally different applied sciences concerned in variants of mass timber, therefore this newest piece.
The standard method begins with milling logs into dimensional lumber. Boards are dried, planed, and glued into perpendicular layers that type cross laminated timber. That is acquainted territory for the sawmill trade, which has been chopping, drying, and delivery lumber for hundreds of years. The benefit is that it matches into present infrastructure and labor practices. Regional sawmills can provide laminates for native cross-laminated timber (CLT) crops with out huge new investments. However the waste streams are vital. Sawing generates kerf losses, knots and defects restrict yields, and never each log may be minimize into ultimate laminates. It’s a confirmed however comparatively inefficient system.
On the opposite finish of the spectrum are veneer and rotary shaving processes. Right here, as a substitute of slicing logs into boards, the logs are spun towards a blade that peels them into lengthy, skinny sheets or strips. These sheets grow to be the feedstock for laminated veneer lumber or may be pressed into hybrid CLT panels. As a result of your complete log may be peeled, the utilization fee is greater and the ensuing laminates have constant mechanical properties. That uniformity is efficacious when making an attempt to standardize structural efficiency at scale. The downside is that veneer-based manufacturing requires specialised, capital-intensive gear. Vegetation must be giant, extremely automated, and equipped with constant log high quality. The payoff is fewer offcuts and decrease uncooked materials prices per ton of completed product, however the barrier to entry is greater.
Past these two major strategies, numerous hybrid and experimental approaches are rising. Some producers are mixing veneer and sawn lumber layers to create panels with predictable energy and decrease waste. Others are experimenting with oriented strand and parallel strand merchandise, which compress lengthy strands of wooden into dense, structural parts. Robotics and automatic milling techniques are coming into the combination, chopping customized laminates with much less labor and fewer waste. These strategies are nonetheless evolving, however they level towards an industrial future for timber that appears extra like auto manufacturing than artisanal carpentry.
One of many debates within the sector is whether or not mass timber ought to rely totally on adhesives or mechanical fasteners. Adhesive-based merchandise, like CLT and laminated veneer lumber (LVL), dominate the market at the moment. They provide excessive energy, predictable efficiency, and well-established testing requirements. The adhesives themselves usually are not with out challenges. They add embodied carbon, some depend on petrochemical inputs, and as soon as cured they make recycling harder. There may be additionally the matter of off-gassing, though fashionable formulations are far safer than earlier variations.
On the opposite aspect are dowel laminated and screw laminated techniques. These use hardwood dowels or lengthy screws pushed via layers of softwood to bind panels mechanically. The enchantment is evident. No adhesives means a cleaner invoice of supplies, simpler disassembly, and probably extra round reuse. However the trade-offs are actual. Mechanical techniques are sometimes weaker, require thicker panels to realize the identical load bearing capability, and are much less standardized in codes and provide chains. Adhesives ship effectivity and scale, whereas dowels and screws provide ecological simplicity and deconstruction potential. Each will discover niches, however it’s unlikely that mechanical fasteners will displace adhesives within the mainstream anytime quickly.
One promising avenue of analysis in mass timber is the event of lignin-based adhesives as a alternative for petrochemical resins. Lignin is a pure polymer that makes up a few quarter of wooden’s mass and is at present handled largely as a low-value byproduct of the pulp and paper trade, typically burned for course of warmth. By changing it into an adhesive, researchers purpose to shut the loop in timber manufacturing, turning waste right into a high-value enter whereas lowering reliance on fossil-derived chemical substances. Early trials present that lignin-derived adhesives can ship comparable bonding energy and sturdiness to standard phenol-formaldehyde or polyurethane techniques, although consistency and scalability stay challenges. If these hurdles are overcome, lignin-based resins might decrease the embodied carbon of mass timber even additional and assist a totally bio-based supplies cycle the place the constructing sector captures extra of the worth chain from the forests it relies on.
Evaluating these approaches aspect by aspect highlights that there isn’t any single right reply. Milling sawn lumber for laminates is sensible for distributed, regional crops close to housing markets that want fast output and the place sawmill capability already exists. Veneer and rotary peeling processes are higher fitted to industrial hubs designed to pump out huge volumes of standardized materials. Adhesive bonding helps world provide chains and tall timber towers, whereas dowel primarily based techniques could enchantment to boutique builders and markets with stricter ecological preferences. In each case, the selection has implications for waste streams, power use, labor necessities, and long run carbon accounting.
The language round mass timber may be complicated, with a number of phrases typically used interchangeably after they really describe totally different merchandise. That’s one thing I’ve been responsible of on this sequence, utilizing CLT because the generic time period as a substitute of mass timber. CLT refers to giant panels made by gluing layers of boards at proper angles, giving energy in each instructions and making it the most typical product for partitions and flooring. Glulam, or glued laminated timber, is comprised of lengthy boards laminated parallel to 1 one other, creating robust beams and columns. LVL makes use of skinny sheets peeled from logs and pressed along with the grain aligned, providing consistency and excessive energy for structural members. Parallel strand lumber and oriented strand lumber compress lengthy strands into dense, engineered parts. Dowel laminated timber and nail laminated timber are alternate options that depend on mechanical fasteners relatively than adhesives. Whereas all fall beneath the umbrella of mass timber, their purposes differ: CLT for panels, glulam for framing, LVL for structural uniformity, and dowel or nail laminated merchandise for lower-carbon or simply disassembled designs.
For Canada, this know-how debate isn’t tutorial. With Mark Carney’s housing plan and stress to chop embodied carbon, the nation should determine whether or not to double down on typical CLT primarily based on dimensional lumber or make the leap to veneer-driven crops that look extra like plywood factories scaled up for housing. There may be additionally the query of whether or not coverage ought to encourage mechanical becoming a member of techniques for disassembly or keep on with adhesives for velocity and energy. Every pathway shapes not solely home housing supply but additionally Canada’s likelihood at turning into an exporter of timber merchandise. The choice is not only about logs and glue. It’s about industrial technique, local weather credibility, and whether or not Canada needs to guide in a cloth that might redefine world development.
Mass timber’s enchantment is easy. It turns timber into carbon-storing buildings that rise quicker and cleaner than their concrete cousins. However the know-how behind it’s something however easy. Milling versus peeling, adhesive versus dowel, distributed mills versus centralized factories. Every alternative determines whether or not the sector grows in matches and begins or scales as much as meet the actual calls for of housing, jobs, and local weather motion. The way forward for mass timber might be written not simply by architects however by the engineers, mill operators, and policymakers who determine how these laminates are made.
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