Purpose - The purpose of the paper is to compare the aesthetic responses of three groups (architects, engineers and non-experts) to a set of non-conventional structures. Design/methodology/approach - A group of 150 respondents (divided into three equal sub-groups of architects, structural engineers, and non-experts) were selected to participate in the main study, which used 14 different non-conventional structural systems. The images of these systems were derived from an earlier pilot study. The evaluation tool included 38 semantic items, also derived from the pilot study. Two statistical analyses were applied to the collected data: factor analysis and ANOVA. Findings - Finds, first, that factor analysis revealed a set of factors identified by all participants as meaningful dimensions, by which they evaluate structural systems. Second, ANOVA revealed differences between the three groups when evaluating different structural systems using the identified factors. Differences between the groups were attributed to their different backgrounds and technical training. Practical implications - The study argues that understanding the aesthetic experience of architects, engineers and ordinary users of structures is essential. First, it helps the designers to establish the basis for selecting appropriate structural methods and materials in relation to building design. Second, it would also help the designers to better understand the relationship between the structure and architecture in terms of a trade-off between the technical and aesthetic issues. Third, it helps the designers to better understand how their designed structures are perceived by the public. Originality/value - This study introduces an alternative approach to the study of the aesthetics of structures, with a focus on non-conventional structures. [ABSTRACT FROM AUTHOR]