This book gathers peer-reviewed contributions presented at the 6th International Conference on Bio-Based Building Materials (ICBBM), held in Rio de Janeiro, Brazil on June 17-20, 2025. Focusing on bio-based building materials (3BM) as well as their applications in sustainable building constructions, the contributions highlight the latest findings in this fast-growing field, addressing topics such as natural fibres- and aggregates, ramped earth, innovative hybrid composites based on bio-based ingredients, novel sustainable binders, energy efficiency aspects- and life cycle analysis of these materials.