The restoration operations carried out on the Chapel (1930’s) were based on the principle of “minimal intervention” to guarantee and respect the wall surfaces and integrations intervened over time. The operations were therefore directed to the elimination of the pathological effects of the degradation, respecting the physiological “alteration” conferred to the materials by the natural aging, while ensuring its protection against atmospheric agents and pollution. At the end of the works, which involved among other things the granite cross placed on the top of the facade, the metal frames of the windows and the staircase and the entrance floor, a polysylloxanic surface protective was applied. The restoration of the terracotta bas-relief was then carried out: given the particular exposure of the work subjected to significant thermal stresses and conditions of high humidity in view of a greater affinity with the porous terracotta matrix and a better performance in terms of durability, an inorganic protective treatment based on functional silica synthesized with sol-gel process was used. As a result of the work carried out it is desirable to carry out in the form of maintenance or “scheduled storage” a constant verification and interventions limited to specific points.