With a glulam-based post-beam building system, a variety of building solutions is offered on the market for multi-story buildings. The building system must be adaptable to the demands of each project. However, short lead-time, efficient manufacturing and assembly must be ensured. The use of product platforms has been acknowledged as an enabler to manage external (customer) and internal (production) efficiency. The building system cannot be locked to a set of standard components as a high level of customisation is required. A set of methods and tools is needed to support the design work and to ensure that solutions stay inside the boundaries of the platform definition. The aim of this work is to map the state-of-practice in the design phase for a glulam building system from a platform theory perspective and outline a path forward for applying a sustainable platform development in companies where a component-based product platform does not suffice. Empirical data were gathered from an on-going product platform development including interviews and document analysis. The results show the lack of definition in platform-based product development from a theoretical perspective and need for development of support methods for design that align with different production strategies.