StructureCraft's DowelLam is changing the game in mass timber construction
“Next-generation mass timber panels are made using wood rather than steel fasteners; steel nails, screws and bolts are replaced by dowel-shaped connections made from hardwood,” says StructureCraft, which through its recently established DowelLam division is beginning to produce acoustic dowel-laminated timber (or ADLT), manufactured at a modern plant in British Columbia, Canada.
In March this year, at the International Mass Timber Conference (IMTC) in Portland, StructureCraft vice-president and head of engineering Lucas Epp will chair a panel discussion on the new landscape for mass timber. A structural engineer, Epp has used the system on more than 100 projects across North America – from Microsoft to Princeton University and the Hines Real Estate T3 portfolio.
DLT is the first mass timber panel to use hardwood dowels to join the edges of softwood sawn timber laminations together – making it stronger, cheaper and more environmentally friendly than cross-laminated timber, and ideally suited to floors, roofs and walls. As the only large-volume supplier of this product on the North American market, StructureCraft says: “ADLT is a high-performance panel that integrates a built-in acoustically absorbent membrane on the underside of the DLT, allowing the mass timber to remain exposed while still meeting structural and noise-reduction requirements.”
“We are delighted to be launching DowelLam – a brand created to develop and supply dowel-laminated timber right across North America,” said Derek Autenrieth, DowelLam sales manager: “Over the past eight years DLT has become a widely recognised mass timber product, and there is no better place than IMTC to demonstrate its broad range of applications and possibilities across every product type.”
Last year Wood Central reported that dowel-shaped connectors are an ideal solution for low-rise and mid-rise building construction, with a study published in the Journal of Building Engineering finding that, for floor-to-wall, wall-to-wall and floor-to-floor connections, hardwood dowels were conclusively shown to deliver greater load-bearing capacity and stiffness than conventional screws.
As researcher Aivars Vilguts* notes: “in recent years hardwood dowels have become one of the most popular fasteners for timber-to-timber connections”, adding that “the most widely used hardwood dowels are made from red oak (USA) and yellow birch”. He added that “experimental tests show that hardwood dowel connections are comparable to, or even better than, screws”.
The study, funded by the US government programme HESTIA (Harnessing Emissions into Structures Taking Inputs from the Atmosphere), found that red oak dowels are twice as strong as ordinary screws. Or, as Vilguts put it, “to achieve the same shear load in a half-lap connection, we would on average need half as many hardwood dowels as screws”. In addition, it was found that when tested under extreme conditions, such as a simulated earthquake, the dowel-based connectors “still operate in the elastic stage without any deformation”.
*Aivars Vilguts. Academic background – Post-doc, Washington State University, USA; PhD Ing. in Timber Structures Engineering, NTNU, Norway; Mg.sc.ing. in Civil Engineering, RTU, Latvia. Research areas – Circular economy and renewable materials. Demountable modular timber buildings and systems. Strength and stiffness in carpentry-type timber connections (timber-to-timber). Wood science and mechanics. Research / experience – Woodsol – timber frame solutions in urban design (Norwegian Research Council). HESTIA – innovative modular timber construction systems (USA). WoodForYouth – boosting the competitiveness of young people in the timber building industry (Interreg CB, 2023)