Installing sandwich roof panels: site preparation, inspection and handover

Confirm the positions of the eaves, ridge and every opening. Openings may need trimming members, while rooftop equipment may require its own supports. Alterations can be costly once panel lengths have been ordered. Before installation, the site manager should check the frame against the drawings and confirm that the measures for safe work at height are in place.

Place the packs so the crew can reach each panel in laying order without repeatedly moving other panels. Follow the product instructions for storage, pack supports and protection from rain. Provide drainage and ventilation. Moisture trapped inside a tightly wrapped wet pack has little opportunity to escape.

Choose the lifting method for the panel weight, length and core, following the lifting device instructions. Set out the lifting route and the exclusion zone. A large panel is difficult to control in wind. Work within the permitted conditions and check that the method suits each panel size in the delivery.

The first panel sets the line for the rest of the roof. Check its position against the eaves and roof edge before fixing it permanently. Follow the system instructions for laying direction and closing the side joint. Handle panels without dragging them across one another, which can damage the coating and joint edges.

Allow for actual cover width and tolerances in the layout, and check alignment at intervals across the roof. This lets the crew correct drift before reaching the last panel. Where panels meet end to end along the slope, the joint needs the specified bearing, factory or site cutback and seals. The design of that end lap must account for the panel core as well as the metal facing.

Select fixings for the supporting material, panel thickness and loads. The number and spacing of screws in the main roof area can differ from those at the perimeter. Give the installers the fixing layout from the design. Adjust the tool so screws seat correctly without crushing the sealing washer or denting the facing.

Fit tapes, gaskets and sealants at the locations specified by the manufacturer. If a joint does not close to the correct shape, correct the fit before sealing it. Pay particular attention to the eaves, ridge and penetrations. Inspect these junctions before the flashings cover them, while corrections are still accessible.

Remove metal swarf as cutting and drilling progress. Use tools permitted by the panel instructions to avoid overheating the coating or scattering hot particles across it. Remove the protective film within the specified period. Inspect the worked areas closely, even if the roof looks clean from a distance.

Agree on roof access, fall protection and permissible loads before anyone walks on the panels. Where a person can step depends on the panel and the location. Brief the trades fitting equipment after the roofers leave. A tool left behind, a metal shaving or a poorly formed penetration can damage a roof that has already passed inspection.

At handover, inspect the surfaces, fasteners, edges and continuity of the junctions. Check that water can drain, penetrations are finished and no core edges remain exposed. Agree on a watertightness test suited to the roof if one is required. Record defects, the repairs needed and whether outstanding flashings have been installed.

Give the operator the as-built drawings, panel identification and inspection schedule. Explain access to gutters and equipment, cleaning requirements and how to report damage. A later photovoltaic installation or a new roof vent calls for another check of the structure and the affected junctions. Keep these documents available for the people maintaining the roof.