How does a sandwich panel work, and what should you check before using it?

Check whether you are buying a steel-faced sandwich panel or a rigid insulation board with a thin facing. Even if the two use the same core material, they are designed for different applications and installation methods. To use a product as the finished cladding of an industrial building, confirm that its specification covers that use.

The product documents give the thermal performance, reaction to fire and available thicknesses for the specified panel variant. To assess load capacity, check the loads and support conditions. Fire resistance requires a separate check for the particular wall or roof assembly and the way it is installed.

For an acoustically sensitive building, identify the sound performance required before comparing prices. Sound absorption describes how a surface absorbs sound. Assessing protection against noise from outside calls for sound insulation data for the wall and an assessment of the whole assembly. Doors, gaps and openings may have more influence on the result than changing the panel.

Manufactured length and cover width help you plan the panel layout. To determine how far a panel can span between supports, check the loads, the specified panel, its facing thicknesses and whether it spans one bay or several. A core thickness of 100 mm supplies only one part of that information.

Draw the openings and edges on the layout so you can use as much of each panel as possible. Check whether the overall width differs from the effective cover width. A longer panel can reduce the number of joints while making transport and replacement harder. On an existing site, allow enough room to manoeuvre it past neighbouring buildings and services.

For a weathertight envelope, engage the joints fully and fit the specified seals and flashings. Choose fixings to suit the supporting material and the loads. Check the frame alignment before fitting the panels. Provide the supports and junction details specified for openings and equipment, including any suspended loads.

Remove swarf after cutting or drilling, protect exposed areas as specified for the system and peel off the protective film within the stated period. Inspect joints while they are still visible. Photographs taken before the flashings go on can help trace a leak later, when the finished trim conceals the detail.

Include panels, accessories, freight and labour in the estimate. Some variants require different lifting equipment or a different support layout. Compare what it costs to enclose the same area to the same performance requirements. A price per square metre on its own can conceal differences in the scope of supply.

Suppose a panel upgrade costs about €4.17 extra per m² excluding VAT. Over 150 m² the additional cost is roughly €625 excluding VAT. Establish what that buys, such as a different coating, improved insulation, lengths cut to suit or compliance with a design requirement. To estimate energy savings and a payback period, use calculations for the whole building. The choice of a PIR core alone cannot establish that period.

Years later, you may need to replace a panel struck by a vehicle, reseal a joint or alter an opening. A record of the system reference, sheet thicknesses, cover width and colour helps identify a suitable replacement. Allow room for access too. Shelving placed directly against a wall can make even a routine joint inspection difficult.

During maintenance, inspect the surfaces, plinth, fixings and drainage. Match cleaning products to the coating. Assess damage to the core or joint before covering it with a temporary repair. If the building changes use, check that the existing envelope meets the requirements of its new function.