The initial fire-fighting facility design plan may need to be changed during the construction of fire-fighting facilities because of alterations in the architectural design or the flexibility of the site situation. The difference between the 'design drawings at the stage of consenting for building approval' (Original design drawings) and the 'design drawings at the stage of consenting for use approval' (Completion drawings) ultimately leads to changes in the construction cost and in the performance of the fire-fighting facility. Therefore, to secure the fire safety of buildings and prevent human casualties, relevant case analyses and consequent institutional and systematic supplementation are necessary. In this study, six recently completed buildings were selected as target sites, the application rate of each fire-fighting facility in the initial design was analysed, and the need for institutional supplementation was suggested. As a result, owing to the design change, the construction cost and net construction cost could be reduced by up to 19% compared to those based on the original design. In particular, In particular, the sprinkler facility was found to match only 78.7% of the original design drawing in the completion drawing, showing the largest rate of design change among fire-fighting facilities.