Abstract: Clustering is widely used as a knowledge discovery method in scientific studies but is not often used in architectural research. This paper applies clustering to a dataset of 129 residential layouts, which were collected from contemporary architectural practices, to reveal underlying design patterns. To achieve this, this paper introduces a novel measure for the topological properties of layouts: ‘grating difference measure’. It was benchmarked against an alternative that measures geometrical properties and the advantages are explained. The grating difference measure indicates the extent of design differences, which is used in the clustering method to obtain the distance between datapoints. The results from clustering were grouped into design schematics and qualitatively assessed, showing a convincing separation of characteristics. The method demonstrated in this paper may be used to reveal topological patterns in datasets of existing designs for both academic and practical purposes.