This study examined differences in the floor-plan preferences of architects and laypersons with no architectural education or experience (non-architects). Qualitative data on floor-plan preferences were collected using interviews and an online survey. The floor plans used in the online survey were differentiated primarily by spatial arrangements and included the original layout of a socialist prefab apartment and two contemporary redesigns of the space. The results showed significant differences in the floor-plan preferences of architects and non-architects. Topological properties of layout and a required level of privacy were identified as key factors influencing the between-group differences. Architects and non-architects disagreed in particular over how the public and private zones were defined and arranged in the apartment layouts. From the perspective of architectural practice, understanding non-architects’ preferences can decrease the uncertainty in new product development for an unknown end user and increase residential satisfaction.