Xylotek has broad experience in mass timber structures, originating in Charley Brentnall's leadership of the renaissance of traditional techniques in the UK in the 1980s. We continue to explore means of developing new structural frame methodologies evolved from both traditional processes and new technologies.
Mass Timber Structures
‘Mass timber’ refers to the use of large-section glulam and CLT in building construction – as opposed to lighter-weight timber framing typically seen in domestic applications. The ecological and carbon benefits of wood – when compared to steel and concrete – are driving the mainstream adoption of mass timber construction which has the additional benefits of prefabrication, including faster and cleaner installation processes on site.
The rise of cross laminated timber is enabling multi-storey construction using CLT panels for walls, floors and roof. Each panel can be fully prefabricated meaning that installation on site is quicker that other construction systems. Connections between panels are achieved cleanly and interior surfaces can potentially be left exposed reducing the need for additional finishes. Whilst CLT walls are themselves well insulating, they typically have further insulation (and envelope cladding) applied externally.
Post-and-beam: spatial flexibility
Timber post and beam construction is an evolution of traditional oak framing techniques, and is a method consisting of vertical posts and horizontal beams connected to form a structural frame. It differs from panel construction in allowing for non-structural walls and for more flexibility with interior spaces. Traditional approaches used hand-hewn beams and columns connected with mortice-and-tenon pegged joints. Contemporary approaches typically use glulam elements with specialist steel connections and can accommodate more complex geometries through digital fabrication technologies.
Combining post-and-beam systems with CLT panels in hybrid configurations is proving to have rich potential. Having discrete posts (rather than more continuously solid walls of a pure CLT solution) allows for glazed curtain walls; long-span beams of efficient depth profiles can be in glulam; and panels of CLT use for flooring between those beams, and as occasional vertical shear panels to provide lateral stability to the building.
Fire performance of mass timber
Whilst perceived as a flammable material, mass timber in fact performs very well in fire scenarios, because the surface of the glulam or CLT element surface chars in way that provides fire protection to the internal wood. Therefore to achieve fire performance the timber section is over-sized to ensure structural integrity during a fire for the required amount of time. Additional fire protection can be achieved through fire resistant lining boards.