What is a sandwich panel?

A sandwich panel (in Dutch sandwichelement) is a building panel consisting of two rigid outer skins with an insulating core between them, bonded or foamed together into a single unit in the factory. The skins are usually coated steel, sometimes aluminium, plywood or fibre cement. The core is PIR or PUR foam, mineral wool or EPS. Because the skins work together via the core, the panel is light yet stiff enough to span large distances between purlins or rails.

Types

• Roof panels: with a profiled, trapezoidal top skin for water run-off. Sometimes with a roof tile profile on the outside.
• Wall panels: flat or lightly profiled, often with concealed fixings for a clean facade.
• Cold store and freezer panels: extra thick, with very airtight joints.

Choosing the core material

• PIR and PUR: insulate best per centimetre of thickness, so they give the thinnest solution.
• Mineral wool (stone wool): heavier and insulates less per centimetre, but is non-combustible. The choice for fire separations and where higher fire requirements apply.
• EPS: cheap and light, but more limited in fire behaviour and temperature resistance.

Insulation value per thickness and fire class vary by product; always take them from the manufacturer’s technical documentation.

Applications

• Roofs and walls of industrial buildings, stables, sheds and storage buildings.
• Barns, garages, garden rooms and canopies that need to be insulated.
• Cold stores and temporary buildings.

Tips for installation

• Cut with a circular saw or jigsaw fitted with a metal blade, not with an angle grinder. Hot grinding sparks burn into the coating and later cause rust spots. Sweep away swarf and drilling debris straight away.
• Keep to the manufacturer’s minimum roof pitch and pay attention to the overlap and sealing of the side and end laps.
• Use the specified screws with sealing washers and do not overtighten them: the washer should just be compressed.
• Remove the protective film in good time. Film left in the sun for a long time is hard to remove.
• Watch out for thermal bridges at junctions with foundations, window frames and the ridge.

Related terms

• Facade panels
• Polyurethane
• Thermal bridge
• Roof covering
• Precast concrete sandwich facade

Want to know more about building terms? Visit our knowledge base at fredsdiyplans.com.