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• Fe-rich precursor was used for alkali-activated roof tiles as a substitute for slate • Pilot production identifies production-specific technological parameters • Casting in a two-layer structure was necessary • Technical performance is comparable to commercially available benchmark solutions • Progress in sustainability can be achieved through large-scale production A new type of slate-mimicking roofing tile based on the alkali-activation of an Fe-rich slag has been developed. The main scientific contribution lies in the targeted valorisation of Fe-rich slag for thin, slate-like roofing elements that must satisfy strict roofing-specific requirements, including a limited thickness, low permeability, freeze–thaw resistance, dimensional stability, and high surface quality. Achieving the required properties and optical appearance necessitated a double-layer setup, where a fibre layer primarily provided the required mechanical properties, while a surface layer ensured the desired optical appearance. The microstructure of the produced roofing tiles was analysed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS) and Hg-porosimetry (MIP), and was compared to reference products on the market. A life cycle assessment (LCA) indicates that the current laboratory-scale production cannot yet compete with established market solutions; however, projected improvements in curing energy efficiency at industrial scale suggest strong potential for environmental competitiveness. Hence these roofing tiles could become an environmentally friendly alternative to current roofing materials. Additionally, a demonstration roof was installed to monitor the long-term performance of the roofing tiles over several years under real seasonal exposure.