A frequently employed tool in the product development process is topology optimization. It is applied in early phases of the development process to derive load-compliant design proposals on basis of given boundary conditions. If these design proposals are supposed to be carried out using conventional manufacturing processes, often high costs arise or, in some cases, it is not feasible at all. A remedy to this problem is additive manufacturing, which has been increasingly used in recent years and is particularly advantageous in the areas of individuality and flexibility. Such an additive manufacturing process is powder bed fusion (PBF), which builds a part layer by layer. The process often consists of two steps within each layer: First, the outer contour of the part is built. Then the inner volume gets consolidated. The division into these two steps ensures that a comparatively high degree of shape fidelity can be achieved. However, at the same time, this procedure also results in three zones of different porosity due to different cooling rates in each layer: The outer contour, the inner area and an area forming in between (interface area). These three zones are created depending on the building direction and exhibit different elastic material properties due to their porosity. This creates a direct link between product design (part geometry) and production system (PBF). Therefore, a method was developed that takes these three zones and the associated varying material properties into account in a density-based topology optimization. This method stops the topology optimization briefly after each iteration, right before the solver. During this stopping, the interim result of the current iteration, which consists of a surface mesh, is smoothed and exported. Subsequently, the developed method subdivides the exported interim result automatically into the three zones (outer contour, inner area and interface area) from the PBF. Afterwards, the corresponding elastic material properties are assigned to each of these zones and passed back to the topology optimization by means of a mapping algorithm, thus serving as input for the next iteration. Finally, the optimization is continued and the described procedure is repeated until a convergence criterion is reached. In order to avoid exceeding the maximum permissible stress, a strength restriction is employed. Since the three zones in each layer depend on the building direction, this paper investigates how different building directions affect the results of the optimization under identical model setup and boundary conditions. For this purpose, three different building directions are considered in the developed optimization method and the arising results are compared. Furthermore, a comparison of the results with those of a standard topology optimization without iterative consideration of the three zones is made. The results confirm the assumption that, due to the formation of the three zones, differences arise in the derived design proposals of the developed optimization method depending on the building direction. This also leads to varying stiffnesses between these design proposals. Furthermore, it can be deduced on basis of the results that the choice of the building direction affects the possible adherence to a maximum permissible stress. Comparing the results with those of the standard topology optimization, it becomes apparent that the developed optimization method always complies better with the maximum permissible stress and provides a lower overall stress level. Thus, it can be concluded that a careful choice of the building direction can lead to design proposals with improved stiffnesses while maintaining the same material usage.