The construction industry plays a key role in future sustainability strategies, as it is responsible for 39% of global carbon dioxide emissions. To counteract the impact generated by the construction sector, it is necessary to direct efforts to make more informed design choices. Although many studies have shown that dry construction systems are able to reduce emissions during the entire life cycle compared to traditional on-site construction, there are circumstances in which the latter must necessarily be used. In the present research, after having identified a gap in the literature between studies that investigate how to reduce the environmental impact of such constructions, the Life Cycle Assessment analysis of a case study is proposed. In particular, the case of a multi-stored building which uses the cast-in-situ reinforced concrete construction system as an executive choice is analyzed. For the LCA analysis the SimaPro software was used and the data obtained lead to identifying the impact categories in the respective pre-use, use and end-of-life phases, through the ReCiPe 2016 Endpoint (H) v.1.05 method, to determining which of these is more impactful and worthy of attention. The study therefore proposes strategic scenarios to mitigate polluting emissions, particularly in the phase of greatest impact, i.e. the pre-use phase.