Cross-laminated timber (CLT) wall

A load-bearing wall of solid timber panels made of boards glued in crosswise layers (X-LAM or CLT). The crossing of the grain makes the panel rigid and stable in both directions, like a large structural plywood. Prefabricated to the millimetre, light and able to store carbon, it bears, encloses and seals in a single element.

The X-LAM (Cross-Laminated Timber) panel brings the logic of plywood into timber at the scale of the building: boards stacked and glued in crosswise layers at 90°, forming a solid panel that works as a load-bearing plate in both directions. It is the heart of massive timber construction, an alternative to the light frame: walls and floors become large prefabricated plates, dry-assembled in a few days.

Timber is anisotropic: strong along the grain, weak and deformable across it, where it shrinks and swells with moisture. By crossing the layers at 90°, X-LAM cancels this weakness: each layer restrains the adjacent one, and the panel becomes rigid and stable in both directions, with negligible in-plane movement. The result is a two-way load-bearing plate, able to act as a wall and a bracing diaphragm, and to distribute loads around openings without added frames.

The panels are CNC-cut in the factory, complete with openings for doors, windows and services, and arrive on site as a kit. Assembly is dry and very fast: they are lifted, positioned and connected with plates, screws and hold-downs that also govern the seismic behaviour. The light weight (a fifth of reinforced concrete for the same volume) reduces the loads on foundations and cranes, and the dry site eliminates curing times. The timber, finally, stores carbon for the whole life of the building.

Solid timber has three fronts to manage. Moisture: the panel must be protected from rain on site and forever, with details that keep it dry and ventilated (dry timber does not rot). Fire: X-LAM is combustible but chars slowly and predictably, preserving the inner resisting section; the R class is reached by calculating the charring rate and with protective linings where needed. Acoustics: the modest mass calls for added layers (screeds, suspended ceilings, insulation) and a careful interruption of flanking transmission at the joints.