A panel is disclosed for use in construction. The panel comprises opposing surfaces that extend between first and second opposite ends. The panel also comprises a plurality of parallel (e.g. sawtooth) ridges. The ridges are provided on at least one of the opposing surfaces. The ridges extend along and adjacent to a first of the opposite ends of the panel for at least a part length thereof. The ridges are arranged to engage with and move past corresponding ridges of an adjacent panel when the panels move relative to each other in opposite directions. The ridges are further arranged so as to interfere with the ridges of the adjacent panel to resist relative movement in a reverse of the opposite direction.