The plastered surfaces were affected by an incoherent and partially coherent, superficial deposit of atmospheric particulate also due to the redeposit of the material carried by the percolation of rainwater coming from the roof, on which it was possible to see the leakages.

Other principal deterioration morphologies are the complete detachment of one or more plaster layers or of the whole plastering layers. In addition a phenomenon of salt efflorescence was detected.

The restoration works on plaster started in June 2014 with the thermographic survey for all walls which was made to detect any hidden wall mosaic under the plaster layers. Then a comprehensive evaluation of the existing plastering layers was made to prepare the mapping and the shop drawings for the restoration works, which included the consolidation of the existing plastering layers, replacing the cement patches with a lime plastering and filling the damaged or missing parts of the plastering layers. The plastering restoration work for the whole Basilica was completed in September, 2016.