Sandwich Panel Upper and Lower Facings

Pre-Painted Galvanised Steel

The steel used in sandwich panels and profiled metal cladding is galvanised by continuous hot-dip processing. In accordance with EN 10142, it receives a zinc coating of 100–275 g/m2 for corrosion protection. A 5-micron primer and the required paint or coating are then applied by coil coating. DX51D+Z galvanised steel is commonly used in sandwich panels. Galvanised steel offers high corrosion resistance and load-bearing capacity. Its resistance to impact and wear reduces maintenance costs. Its recyclability also makes it an environmentally conscious building material.

Aluminium

Aluminium used as an upper or lower facing in sandwich panels can be coil-coated, lacquered or embossed. It has high corrosion resistance and good conductivity. Its higher expansion coefficient compared with galvanised steel makes it a preferred option in acidic environments or heavy industrial conditions. For single-skin profiled sheets and sandwich panels, a minimum thickness of 0.70 mm is required for the load-bearing facing.

GRP (Glass-Reinforced Plastic)

GRP is a semi-transparent composite made by combining glass fibre and resin. It resists corrosion, chemicals and high temperatures. It is used as a daylight panel in buildings and as the lower skin of composite sandwich panels in poultry farms, food facilities and acidic environments. GRP withstands temperatures from −40 to 120°C, resists impact and does not deform under heat within its operating range.

PET (Polyethylene Terephthalate)

Polyethylene terephthalate is a thermoplastic in the polyester family, produced by polycondensation. It has low impact resistance but resists breakage. It begins to soften at 70–80°C and melts at 235–260°C. Used as a gas and moisture barrier, PET also serves as the lower skin of composite sandwich panels in poultry farms, food facilities and acidic environments.