Timber floor (X-LAM)

A floor of X-LAM panels acting as a light, prefabricated horizontal load-bearing plate. A concrete topping, connected to the timber, can turn it into a stiffer, quieter composite section; a resilient layer and added mass govern the acoustics, the real test of lightweight floors.

The X-LAM floor brings the logic of massive timber construction into the horizontal: large cross-laminated panels, prefabricated and dry-assembled, acting as a load-bearing plate. Light and fast, it nonetheless reverses the acoustic problem compared with heavy floors: the modest mass must be integrated with care, and it is often worth making it work together with a concrete topping.

The X-LAM panel works in bending like a plate, often in one direction (main span) but with a useful transverse collaboration given by the crossed layers. It is sized on strength and, above all, on deflection and vibration: timber floors, being light, are sensitive to footfall vibration, which must be checked for comfort. Prefabrication allows significant spans with modest thicknesses and short installation times.

By connecting a concrete topping to the panel with screws or connectors, the two parts work together: the concrete, on top, works in compression; the timber, below, in tension. The composite section (Timber-Concrete Composite) markedly increases stiffness and load capacity, reduces vibration and adds mass valuable for acoustics and fire resistance. It is the solution of choice for the longer spans and for the refurbishment of existing timber floors.

Acoustics is the critical point: the modest mass readily transmits impact noise. One intervenes with a resilient layer, added mass (topping, gravel, dry screed) and a decoupled ceiling, building a mass-spring-mass system. Fire is managed as for any timber element: slow, predictable charring, a design section and, where needed, protective linings on the soffit. Moisture tightness, finally, must be ensured on site and at the joints.