Façade system

A plank for an extruded plank façade system comprising a plurality of such planks as cladding suitable for a vertical walling structure, the plank being of the type comprising a facia, a joining lip, and an attachment hook structure,

• wherein the joining lip is recessed behind the facia and extends along a side of the facia to be at least partially overlapped by an adjacent facia of another plank to be provided and to define at least part of a joint groove between the facia and the adjacent facia,
• wherein the attachment hook structure extends back behind the facia to allow the plank to engage, via the attachment hook structure, a retainer fixed to the walling structure,
• wherein the plank further comprises a rail to at least partially conceal the attachment hook structure, and
• wherein the joining lip comprises a plurality of alignment features for positioning another retainer to be provided, the other retainer to be engaged by an adjacent plank,
• wherein the alignment features are arranged on the joining lip, and wherein each alignment feature permits a tight seating with said other retainer at different distances from the facia, such that aligning the other retainer with any one of the alignment features defines an interstitial distance of the joint groove between the facia and the adjacent facia.