This book gathers peer-reviewed contributions presented at the 1st Biennial RILEM Youth Symposium (RYS), organized by the RILEM Youth Council, held virtually on October 20–21, 2025. By focusing on building materials and construction, this book covers topics such as the processing, characterisation and advanced manufacturing of building materials; deterioration and durability; structural performance; and the environmental impact evaluations. It encompasses both conventional and non-conventional building materials: concrete and cementitious materials, masonry, timber, bio- and earth-based composites, bamboo, polymers and innovative low-carbon materials applied in construction.