A tie system and method for forming a wall from a hardenable building material over a footing. The tie system includes multiple wall ties configured to be directly interconnected to form a wall tie stack such that multiple wall tie stacks can be positioned over the footing in a spaced apart, vertically extending arrangement. Each wall tie includes first and second planar surfaces to be directly fastened to respective first and second panel structures. In one embodiment, the tie system includes tabs for supporting multiple insulation panels positioned between the vertically extending tie stacks and between the first and second panel structures.