Construction project delays remain a persistent issue, often exacerbated by variation orders that adversely affect both financial and environmental performance, even in the UK. Although Modern Methods of Construction (MMC) have been increasingly employed to mitigate delays and improve efficiency, limited research has examined how variations affect small- and medium-sized enterprises (SMEs) adopting MMC in the UK construction sector. Given the pivotal role of SMEs and their financial vulnerability, this study examines the key challenges posed by variation orders for SMEs adopting MMC, with the broader aim of enhancing future project performance. Employing a two-stage iterative methodology, the research first identifies challenges through a comprehensive literature review, followed by a questionnaire survey and expert interviews. The resulting data were analysed thematically and statistically using SPSS and subsequently validated through a detailed case study involving interviews and document analysis. The findings highlight three principal clusters of challenges: operational, contractual, and module alteration-related, of which operational issues, particularly cost discrepancies, client approval delays, and rework, exert the most significant influence. The study provides a structured understanding of these interlinked challenges and underscores the need for targeted mitigation strategies to improve productivity and performance among UK construction SMEs engaged in MMC projects.
Mubashar et al. (2026) studied this question.