Designing out waste implementation in the wall system of residential projects in New Zealand

The construction industry accounts for approximately half of all landfill waste in New Zealand (NZ). Designing out waste (DoW) approach has been introduced to minimise waste generation at the design stage, including five key principles: design for off-site construction, reuse and recovery, materials optimisation, waste-efficient procurement, and design for the future. However, the differential applicability of these principles across various building elements poses significant challenges to their practical implementation, while existing guidelines offer only broad and nonspecific recommendations. This study addresses this gap by investigating the application of DoW principles to wall elements, including framing, insulation, lining, and cladding, in residential construction, a sector that accounts for the largest share of NZ construction activity and where wall systems are the major source of material waste. Through a desktop study and fourteen semi-structured interviews, this research investigates the feasibility of applying each DoW principle to materials used in wall systems. Furthermore, five key project factors influencing DoW implementation were identified: project budget, regulatory compliance, accessibility of waste processing infrastructure, material availability and supply chain collaboration, and technical requirements. These factors highlight the importance of project context in determining which DoW strategies can be effectively adopted. The study offers practical and specific guidance to support more effective integration of DoW strategies from the design stage, ultimately contributing to waste minimisation in residential construction. • Designing out waste (DoW) is a critical approach to minimise construction and demolition waste. • Existing guidelines offer broad and nonspecific recommendations, limiting practical implementation. • Material-specific DoW waste strategies were developed for the New Zealand residential wall system. • Five project factors were identified that influence the applicability and outcomes of DoW implementation. • Findings provide detailed and practical guidance to apply DoW from the design stage of the NZ residential wall system.