A sudden lockdown was declared on 14 March 2020 due to COVID-19 crisis, leading to animmediate change from face-to-face to online learning in all universities within Spanish jurisdiction.At La Salle School of Architecture, the Concrete and Steel Structures subject started online classesimmediately after the lockdown law was published, using a methodology based on the flippedclassroom approach and adapting the monitoring of the student to the virtual environment. Thisarticle presents a pilot study to analyze the adaptation of the model to the online format using amixed approach in which qualitative and quantitative surveys were conducted at the end of thecourse with 48 participants. Responses from both surveys were organized according to six categories(teachers, assessment, methods, class development, students and documents) and 14 subcategories, asdeveloped in an undergoing research project involving the subject since the academic year 2017/2018.Thus, the open responses of the students have been analyzed alongside with the quantitative data.The results demonstrate a proper adaptation of the model, as well as the negative perception of thestudents of the online format due to the loss of face-to-face benefits of the flipped classroom.