An external cladding system includes at least one panel of sheet material, a series of vertically and horizontally oriented panel mounting extrusions, and a number of spaced apart apertures passing through a topmost/bottom most horizontal panel mounting extrusions on a wall. The apertures extend along a longitudinal axis of an internal horizontal portion of the topmost and bottom-most panel mounting extrusions. In use, the at least one panel is held in place on the panel mounting extrusions via: capping extrusions and resilient sealing strips, which are located between the panel and the capping extrusions. One or more spacer elements are located on the horizontally-oriented panel mounting extrusions, which support the bottom edge of a panel.