Fastener holes are the number one failure point on metal and sandwich panel roofs — rubber washers under screw heads degrade under UAE sun exposure and eventually let water through.
Lap joints between panels, especially on low-pitch roofs, are the next most common leak source once the factory sealant ages.
A protective waterproof coating applied over the full roof — sealing fasteners, laps and flashings together — is usually far more cost-effective than a full roof replacement.