Modeling interdependent constraints on modular construction: a constraint theory and fuzzy-PLS-SEM approach for developing countries

Purpose This study aims to develop an integrated analytical framework to evaluate the barriers limiting modular construction adoption in residential projects within developing countries, emphasizing a structured examination of their severity and interdependencies. Design/methodology/approach A mixed-method research design was employed. The process began with a systematic literature review and a Delphi study to identify 20 key barriers, later refined to fifteen significant indicators. These were categorized using constraint theory into physical, financial, organizational and policy groups. The analytical approach integrated two techniques: fuzzy set theory (FST) was applied to convert linguistic expert assessments into calibrated quantitative scores, addressing uncertainty in judgments; followed by partial least squares structural equation modeling (PLS-SEM) to examine structural interdependencies among barrier categories and generate a composite barrier index. Data were collected from 371 validated professional responses from the Egyptian construction industry. Findings The analysis reveals that financial and physical constraints are the most influential. Key barriers include high capital costs, transportation challenges, design freeze and a shortage of experienced designers. Organizational and policy-related constraints, though comparatively weaker, also remain significant. The hybrid model effectively captured uncertainty in expert input while exposing latent structural relationships, producing a robust ranking of critical barriers. Originality/value This study proposes a novel framework that innovatively integrates FST and PLS-SEM to model both uncertainty and interdependence. Methodologically, it develops a composite barrier index for systematic prioritization. Contextually, it is uniquely tailored to data-scarce environments in developing countries, providing a practical decision-support tool for policymakers and practitioners in the modular housing sector.