Experiences with external drainage systems from compact roofs in Norwegian climates Erlend Andenæs, Vegard A. Skagseth, Nora S. Bunkholt, Tore Kvande and Jardar Lohne E3S Web Conf., 172 (2020) 21010 Published online: 30 June 2020 DOI: 10.1051/e3sconf/202017221010