15–25 m Span

S2 is the step where the series changes character. A distinct CFS lattice roof truss replaces the portal beam; twenty-five metres is the span at which a single-piece beam stops being economical.

The truss solution has a second consequence: the roof can be built flat or at a very low pitch. At the same clear height that means less enclosed volume — less empty space to heat.

Here the galvanised structure is not only a material preference but an operating cost decision. A painted system comes with an annual maintenance programme; galvanising does not.

Seismic calculations are project-specific — the system is designed for the region where it will stand, not for a generic one.