The sandwich panel is the apotheosis of composite engineering. Copying the structural principle of the IPE beam, it transforms two floppy half-millimetre steel sheets and a fragile foam into a self-supporting wall capable of withstanding hurricanes and providing cold-store insulation.
When wind pushes on the facade, the outer skin goes into compression and the inner skin into tension. Without the foam, the two skins would slide over each other and immediately buckle. The polyurethane core absorbs the shear force, locking the relative movement and forcing the skins to act together. This generates enormous flexural rigidity, allowing a 100mm-thick lightweight panel to span 6 metres between steel columns with no intermediate supports.
Panel performance depends on the sandwiched material. Polyisocyanurate (PIR), the evolution of classic PUR, offers unrivalled thermal insulation (lambda = 0.022 W/mK), ideal for cold chains, controlled logistics and roofing. When the critical factor becomes fire resistance (compartment walls) or acoustic insulation, a Rock Wool core with oriented fibres is used. This material is totally non-combustible (Euroclass A2) and absorbs sound waves, guaranteeing REI resistance up to 120 minutes.
Standards
European and international references applicable.
Physical properties
Usage environment
BOWING EFFECT: a dark external skin (anthracite) can reach 80 degrees C in summer while the internal skin stays at 20 degrees C, seasonally bowing the panel outward. Always calculate to avoid fixing screw tear-out on large vertical panels. CUT-EDGE: always use cold cutting tools, never an angle grinder. The bare steel edge must be sealed with finishing paint to prevent corrosion.