A typology-based approach to standardized floor plans for timber-specific bathroom design

The rapid expansion of cross-laminated timber (CLT) construction is reshaping contemporary building practice. Yet the integration of plumbing systems remains a critical, underdeveloped challenge. Undetected leaks in such systems pose a disproportionate risk in timber buildings, where prolonged moisture ingress can compromise structural integrity and result in costly, complex remediation. Bathrooms are particularly vulnerable, demanding adapted design and plumbing strategies. This paper introduces a typology-based approach for standardized, timber-specific bathroom design that integrates plumbing requirements from the earliest design stages. Drawing on a dataset of 1163 bathroom floor plans from 34 residential projects in Austria, the study demonstrates that apparent design diversity conceals a high degree of regularity: 17 bathroom types account for more than 78% of all plans. The analysis identifies frequently occurring bathroom types and types of bathroom-adjacent room configurations containing plumbing fixtures. Additionally, it revealed bathroom-adjacent room types with potential for compact plumbing integration. Based on this, the study proposes a catalog of standardized floor plans for bathroom and bathroom-adjacent room types, incorporating timber-specific plumbing principles and waterproofing strategies for residential buildings with four stories in Austria. By translating typological findings into standardized floor plans, the proposed framework provides a structured basis for timber-specific bathroom design. It is expected that the application of the proposed standardized floor plans could contribute to reduced planning complexity, improved moisture safety, and the advancement of industrialized construction processes in the context of multistory CLT buildings in Austria. Nevertheless, these anticipated benefits remain hypothetical and require validation through future implementation and research.