The project deals with demographic transition theories, namely the diffusion of demographic change in the last three decades in the Czech Republic. The project further focuses on how demographic processes changed over space and time at the community level, and it will investigate whether the diffusion theory can be accepted in the context of recent demographic developments. The diffusion hypothesis between 1990 and 2015 is tested using a set of research questions. Attention is given to population ageing examined at the community level. The analysis is based on dynamics of age structures during this period and across the community level. The authors suggest and use the concept of the minimal household unit. The newly proposed classification of private households is based on the combinations of living arrangements, the presence or absence of children, and according to the age groups of adults and children. The top 10 living arrangements are used for spatial analysis at the community level. Finally, spatial patterns analysis of newly defined private households will be addressed.