Abstract: A plurality of pre-formed panels are provided. Each panel comprises construction boards held apart from each other by spaced apertured metal strength members (2) to form a sandwich construction. Each strength member is provided with at least one bar (10) extending beyond an edge of the construction boards. Each strength member has a bar receiving portion (63) associated with its end opposite the at least one bar. To construct a wall, a first such panel is first erected with its strength members (2) extending vertically and with the bars (10) projecting above the remainder of the panel. The void between the construction boards is then filled with a settable material. A second panel is located vertically above the first by slotting the bars of the first panel into bar receiving portions of strength members in the second panel. Thereafter, the void between the construction boards of the second panel is filled with the settable material.