The ability to offer customisation has been considered as a competitive advantage for industrialised house building (IHB) companies. Product platform approaches have been acknowledged as one of the prominent ways to improve both internal and external efficiency. However, the use of traditional platform-based strategies does not suffice for the design of engineer-to-order (ETO)-based components in a building system. The purpose of this research is to test and evaluate how the reuse of design assets can be achieved by using a parametric modelling approach to support the design process of ETO-based components in a post and beam building system. This is an additional study using the design platform approach (DPA) that contributes to expanding the knowledge for designing ETO-based components. This research proposes a parametric design platform method developed by following an inductive approach based on the findings from a detailed study on bracket connection with a single case study in a Swedish multi-storey house building company. The proposed method offers flexibility in modelling ETO building components, facilitates design automation, and shows a 20-times improvement in the modelling process. This approach can be used in any building system with ETO-based components by identifying, formalising, and reusing connected design assets. A key finding is that the ETO components can be shifted towards configurable solutions to achieve platform-based design.