There are currently 70.8 million forcibly displaced people, globally. Bangladesh hosts the largest refugee camp in the world. Much effort has gone into the research, design and delivery of mass-produced shelters. Yet most refugees live in self-built shelters using simple shelter materials. This paper aims to demonstrate the benefits of using a transdisciplinary approach for holistic data collection in such shelters. A total of 1594 households were surveyed in refugee camps in Bangladesh using diverse methods – e.g surveys, semi-structured interviews, physical measurements. It was only because of the use of various methods that the reasons behind identified issues were discovered or quantified. For example, household surveys uncovered the issue of poor ventilation, but only the semi-structured interviews exposed the reasons behind it, while physical measurements assessed the implications of this – annual particulate exposure 13 times the recommended limit. Furthermore, several methods pointed to issues with materials, but only the focus groups discussions exposed the need for gender-sensitive technical training tailored for women on the correct use of the materials. This study demonstrates that a diverse team (humanitarian staff, building physicists, and anthropologists) using several approaches to data-gathering and working in a transdisciplinary manner has much to offer the sector, and by including quantitative physical measurements allows costed improvement plans to be developed, targets to be set and general, rather than case specific, knowledge to be generated. The findings of this study have resulted in new shelter interventions by the aid sector that were rolled out in over 70,000 shelters.