Life Cycle Assessment (LCA) finds its application in many areas of today’s building sector. Calculations of building LCAs are based on extensive databases that deliver datasets for building materials and processes. As there is a need for high quality and validity of these datasets they have to be reviewed thoroughly. In this paper six databases are compared using the LCA calculation of three different wall constructions as a reference. The results show a trend regarding the Global Warming Potential (GWP), whereas they diverge for the Cumulative Energy Demand (CED). There are significant differences between the results for each wall assembly depending on which database is used. As one of many levers affecting the results a major difference between ecoinvent and ökobaudat in the method of allocation is identified. As a conclusion the paper underlines the importance of such comparisons and recommends an increasing effort in making the background information of each dataset publicly available.