Price movements in the residential property market are often small-scale and can lead to regional over- / undervaluations that cannot be reported on an aggregated level. However, the derivation of regionalized price developments demands for appropriate methods and sufficient big data sample sizes. Therefore, the Austrian residential property price Index, which is published quarterly by Oesterreichische Nationalbank (OeNB), has been methodically revised: Instead of the previously used time dummy approach, which only allows for an evaluation at the model region level, the new index is based on double imputation methods, which makes possible an almost arbitrary regionalization. In this study, we describe the impact of the methodical changes on the index developments on an aggregated level. Furthermore, the new models allow a more granular regional breakdown of the index series. The resulting data series can be used for a more detailed monitoring of developments in the residential property market and can serve even as an input for a more granular regionalized fundamental indicator for residential property prices.