Installing sandwich panels on cold-formed steel: checks before closing the envelope

Confirm which drawing revision governs the work. Following a change to the steelwork, review the panel layout and fastener schedule. Moving a single rail can affect more than one panel. Circulating the same revision to both crews keeps them working to the same detail.

Check purlin and rail spacing, straightness and the plane of the fixing faces. Confirm bearing widths at typical and special supports. Panel joints, openings and corners may need additional members. These are easiest to install before cladding starts.

Do not use a panel to straighten misaligned steelwork. Pulling it into place by force can impair panel behaviour and make a joint difficult to seal. Agree how deviations will be corrected. Shims and extra plates can change the connection behaviour. Start installation from a correctly aligned support plane.

Compare each C, Z or sigma section with the schedule. Check flange dimensions, sheet thickness and hole pattern as well as section depth. A difference in steel thickness can change the screw required for the panel. Verify that the selected fastener suits the steel actually installed.

Where the secondary framing includes hat sections, verify their function and shape. A narrow crown must line up accurately with the fixing centres. Check member markings before covering them. Similar-looking sections with different hole patterns or geometry are easier to identify now than when drilling starts.

Install the connections and restraints required for the current erection stage. Check ties, fasteners and bracing against the plan. Cladding must not take the place of a missing structural member. Where the design relies on restraint from the panels, install the specified fixing pattern.

Lay the panels in the sequence required by the erection plan and the stability conditions. Only set down bundles on a partly completed roof at locations prepared for that purpose. Plan the lifting operation and landing positions so prefabricated panels can be handled without imposing unintended loads on the lightweight steelwork.

Select screws for the substrate material, steel thickness and panel thickness at the fixing position. Check exposure requirements and the specified washers. Count fasteners by cladding zone because the number required can change across the façade or roof.

Match tapes, sealants and flashings to the individual details. A material substitution can change compression or joint geometry. Assemble the required components and tools in advance to avoid interruptions and follow the installation method specified for the system.

Clean machining debris from the galvanised sections and inspect the coating for damage. Use a repair method appropriate to the finish. A distorted web or flange requires a separate structural assessment. Painting over the area addresses neither the deformation nor its effect on the member.

Look for details that can trap water. A local leak may remain hidden after the envelope is closed. Use the steelwork handover to check the routes of seals and flashings, particularly at plinths, roof edges and openings where several materials meet.

Record which bays are ready for cladding and which corrections are outstanding. Note agreed deviations and update the drawings. A concise, unambiguous as-built record helps with handover, later inspections and future extensions.

Correctly prepared galvanised sections provide the intended bearing and fixing points for the panels. Z purlins, channels, sigma and hat sections each serve a different purpose, and their alignment affects the finished surface. Checking them before covering the frame reduces remedial work and lets installers follow the agreed sequence from one panel to the next.