How do you specify the appearance and installation of a sandwich panel façade?

Wall panels are used on industrial buildings, workshops, pavilions and service buildings. Each factory-made unit combines outer and inner facings with an insulating core. Once installed on the supporting frame, it provides a weather barrier and insulation, reducing the number of separate operations on site.

Consider conditions on both sides of the wall. A dry warehouse, a heated workshop and a humid room make different demands on the internal face. Assess external exposure too. An attractive finish at handover is no guarantee that the coating will withstand every chemical or corrosive environment.

With exposed fixing, fasteners pass through the facing at the points specified for the system. Concealed-fix panels hide them in the joint, giving the façade a less interrupted appearance. The two arrangements do not necessarily have the same load capacity or use the same installation method.

The interlocking edge belongs to a specific panel design. It determines how neighbouring panels engage and how the joint runs. Do not trim or bend it arbitrarily or substitute an unrelated profile. Check seals and access for tools when specifying the system: a joint that looks neat on a drawing is of little use if the installer cannot drive the fastener correctly.

Horizontal joints can make a façade look longer; vertical joints emphasise height. Orientation also affects the support layout, corner junctions and flashings around openings. Draw the elevation using the actual panel cover width. A narrow unplanned cut beside a door can disrupt the pattern of the whole wall.

Dark colours heat up more in sunlight. Product documents may therefore specify different panel lengths or design limits for different colours. Do not assume the span allowed for a pale facing also applies to a dark one. Inspect samples outdoors: smooth and micro-profiled surfaces reflect light differently and make joints stand out to different degrees.

Select the core thickness for the performance required of the wall. Compare the declared U-value of the specific panel, rather than just the thermal conductivity of the foam. Joints and fixings also affect the assessment of the complete wall. Panels of equal thickness need not have equal thermal performance.

PIR gives good thermal insulation at a relatively small thickness, but it is not non-combustible. Where fire requirements govern, a mineral wool core may be more suitable. Reaction to fire is different from the fire resistance of a wall. Verify the required classification for the actual assembly, thickness and installation arrangement.

Besides panel joints, inspect the base of the wall, corners, roof junctions and window flashings. Water needs a clear route to the outside; avoid pockets where moisture can collect. On the heated side, airtight connections are also important, particularly where the panels meet a different wall or roof construction.

Choose fasteners for the support material, panel thickness and design loads. A timber screw is not necessarily suitable for a steel rail. Follow the design for fixing numbers and positions. Do not pull a panel against an uneven frame by tightening its screws: check the support plane and installation tolerances first.

At handover, look along the wall and inspect it in light from the side. Dents, distortion around screws or uneven supports may be easier to see. A visible irregularity does not by itself prove a loss of capacity, but establish its cause before closing out the work. Assess appearance using the criteria agreed for the supply.

Prepare elevations of every wall, showing window, door and loading-door dimensions. Allow for effective cover width and installation direction. Long panels require suitable vehicles and lifting equipment. Check that the site has space for safe unloading and storage without damage to the joint edges.

Include flashings, seals, fixings and delivery in the quotation. Check how long the protective film may remain in place. After installation, remove swarf and inspect the coating beside cuts. Consistent, well-executed details give a panel façade its finished appearance; colour alone cannot disguise poor setting out.