The interwar period was particularly crucial for urban policies in Europe because it was characterized by an intense architectural and programmatic debate concerning the form of the city and the production of social housing. Of the European experiences Das rote Wien (Vienna, 1919-1934) and Das neue Frankfurt (Frankfurt am Main, 1925-1933) developed the most convincing typological solutions in answer to issues raised by housing problems in the nineteenth century. In this perspective, the Viennese Kleinwohnung (small flat) and the Frankfurt Existenzminimum (minimum dwelling) correspond to two alternative, but complementary, dwelling types. The objective of this paper is to draw a comparison of these opposite architectural types according to the following criteria: dimensions, distribution, and spatial composition. Despite their evident differences, both are the result of a modern and rational approach for designing the affordable housing as well as for promoting a new living culture (Wohnkultur). The main concern is the achieved comfort: for example, by adding the entrance hall, the equipped kitchen, the toilets, and an efficient organization of rooms. They constitute an improvement of the hygienic conditions, but also the accomplishment of a democratization program, which means to eliminate the distinction between social classes. The analysis is realized using critical re-drawings of the houses plans in order to get the highest graphic homogeneity. Therefore, the aim of this study is the critical comparison of a selection of case studies from an architectural point of view. Architectural historians and critics have often neglected or observed in an ideological perspective these examples. Today, looking at those the typological solutions means a new approach for a better comprehension and a wider viewpoint of 1920s’ social housing experiences. The comparative approach that animates this paper allows the analysis of several case studies through homogeneous tools. The systematic use of redrawing stress the key role of some architectural solutions, which are still today in the centre of housing debate.