Purpose This study is based on a research approach proposal aiming to reveal tacit knowledge that shapes architectural design processes through subjective accumulations and tools. With the premise that design embodies tacit and personal knowledge, it proposes an alternative way to decipher this subjective medium. Design/methodology/approach The proposed research approach, "(architectural) design research through reflection", basically belongs to "research by design" method and narrowed in the focus of reflection. It enables to study how tacit knowledge functions within processes of architectural design without being its very subject. The proposal and the product of the approach, revealing diagram, are developed through the "architect's" tools and the involvement of the "researchers" in the process. It is also supported by a conceptual basis created from literature on reflection. Findings By means of the proposal, the reflective accumulation of the subjects, that is, the tacit knowledge, is investigated in relation to practice. The revealing diagram is presented as a tool through which relations can be interpreted within the framework of subjects. It is a tool by which the subjects, tools and processes of the architectural design product can be analysed. Originality/value The study contributes to architectural research by shifting the perspective on reflective knowledge that shapes design processes.