This disclosure relates to a formwork element and a formwork assembly, that can be used to mould upwardly extending building features such as columns or walls that extend between adjacent floor slabs. In one fonn, the fonnwork assembly comprises at least two surface fonning elements, wherein each surface forming element comprises a casting surface and a pair of lengthwise extending parallel edges. In use, the surface forming elements are stacked by abutting along these edges, and each of these edges comprises a means for interlocking the surface forming elements with respect to each other so that the resulting formwork assembly forms a single, continuous casting surface.