Sandwich panel (composite building panel)

Construction and typical materials

Core types and facing materials vary to meet mechanical, thermal and fire-performance requirements. Common face materials include aluminium, steel, glass-fibre reinforced plastic and plywood, while cores are often foam (EPS, PIR, polyurethane), mineral wool or honeycomb (aluminium or aramid). The core transfers shear between faces and maintains spacing; the faces carry bending stresses.

• Face sheets: aluminium composite panels (ACP) and coated metal are popular for cladding.
• Cores: foam cores for thermal insulation, mineral wool for fire resistance, honeycomb for extreme stiffness.
• Bonding: continuous lamination or adhesive bonding with protective edge treatments.

History and development

Sandwich construction traces to early aerospace and marine uses, where lightweight rigidity was essential. Over decades the concept migrated into building façades and industrial applications as manufacturing methods and polymer foams improved. Architectural aluminium composite panels became widespread from the late 20th century as finishes and coatings advanced.

Uses, advantages and examples

Panels are used for external cladding, insulating roof and wall panels, internal partitions, cold rooms, vehicle bodies and aircraft interiors. Advantages include rapid installation, good thermal performance per unit thickness, and a clean external appearance. Designers choose materials to balance cost, weight, insulation, acoustic performance and durability. See manufacturer guidance for specific applications at technical references.

Fire performance, standards and risks

Fire behaviour depends primarily on the core material. Mineral wool cores are non-combustible; some polymer foam cores are combustible and can contribute to rapid fire spread in cladding systems. Because of this, many jurisdictions require testing and certification to national or international standards; look to applicable codes and lab tests when specifying panels. For more on material safety and codes consult regulatory sources and product datasheets.

Installation, maintenance and distinctions

Proper detailing of joints, fixings and edges affects thermal bridging, weather tightness and fire compartmentation. Panels may be mechanically fastened, interlocked or bonded; flashings and sealants are used at interfaces. Regular inspection preserves finishes and detects insulation or moisture issues. When selecting panels, compare core chemistry, facing durability and certification status. For industry practices and guidance see industry guidance.