How does a sandwich panel work and what should you check before buying?

Damage to the bond can matter even if it is barely visible. Conversely, a small patch of dirt on the coating need not indicate core damage. Assess the surface condition separately from the integrity of the panel. Do not assume that insulation sold under a similar name has the properties declared for the complete panel.

Roof panels are shaped for use on a roof slope. Their profile and joints accommodate drainage and the required fixings. Wall panels may have shallow profiling or almost flat facings, with several options for concealed fixings. Choose according to the requirements and documentation for the particular system.

Matching core thickness does not make wall and roof panels interchangeable. Loads and end details also matter. Similar-looking undersides are no proof of suitability. For a suspended ceiling or a chamber, check that the product is intended for that specific use. Approval for a wall does not establish suitability elsewhere.

Lambda describes the thermal conductivity of a material. The U-value describes heat transfer through a building element or assembly under specified conditions. Within a like-for-like comparison, lower values generally indicate less heat transfer. The two quantities have different units.

Dividing the insulation thickness by its conductivity gives the layer’s thermal resistance. Use the declared U-value for the panel itself, as joints and the assessment method can matter. In the building, junctions and openings also affect heat loss. A low advertised core conductivity alone is therefore insufficient for selection.

Each load table applies to a particular combination of panel type, facing thickness, supports and service conditions. The designer checks these against the loads on the building. Use the row for the actual configuration. Matching insulation thickness alone is insufficient. The length supplied is different from the span a panel can bridge between supports.

Fire classifications also have a defined scope. Reaction to fire describes a material or product, whereas fire resistance relates to the performance of the assembly. Fire resistance can depend on installation, span and joint details. Knowing that a core contains mineral wool or foam cannot replace evidence for the complete system.

Identify the exact product and its declared performance. The technical data sheet gives dimensions, weight, facings and intended use. Instructions cover handling and installation. The designer may also need load tables and classification documents. Each answers a different question.

Check that the pack labels match the order before unpacking the whole delivery. Documents for a similar panel do not establish the properties of the variant supplied. Obtain any missing data before assuming that two similarly constructed products perform alike.

The supporting structure, fixings and continuity at joints all matter alongside the product itself. Flashings protect exposed ends and direct water along the intended path. Seals must be positioned where the detail requires them. Good panel performance cannot compensate for poor installation.

Once the building is in use, inspect and clean the panels in a way suited to the coating. New openings or equipment can affect loads and weather tightness. Keep the documentation and establish who will assess alterations. Decisions made during use continue to affect how the envelope performs.