The German architect Heinrich Leppla (1905-1980), after training at the Bauhochschule in Weimar, joined the Bureau of J.H. van den Broek in Rotterdam with a detour at the end of 1929. The influence of two of his teachers, Cornelis van Eesteren and Ernst Neufert, was evident within this bureau. With the arrival of this young German, a strong research department emerged within the firm. This allowed a more academic approach to housing to be developed. For example, one of the researches consisted of needs and necessities for residents in their homes, the proper proportions, sizes and relationships between rooms. Another example is a study of amenities and circulation / walking routes in a home. When Leppla left the firm in 1934 to start his own office in Schiedam, research into different housing typologies was in full swing, especially the development of semi-open building blocks. The major projects in Bergolder and on Vroesenlaan (De Eendracht) function as major try-outs and symbolize a major advance within this research.