Design and construction of provisional works for the maintenance of extra-ordinary buildings in the eighteenth century: the wooden scaffolding for the main nave of St. Peter’s Basilica in the Vatican

Restoration works conducted in St. Peter's Basilica since the late seventeenth century provide evidence of the technological evolution of scaffolding systems in pre-industrial times. As recent studies have shown, the Vatican scaffoldings were considered a benchmark. Their prolonged fortune is evidenced by their citation in Northern European carpentry manuals until the early twentieth century. This paper provides an insight on geometric, structural, and functional details of maintenance scaffolding in the 18th century through the combined use of historical analysis and, both physical and digital modelling. The scaffolding designed in 1773 by Pietro Albertini for the restoration of the main nave of St. Peter’s Basilica in the Vatican is presented as a case study. The combination of historical studies and both digital and physical modelling allowed to acquire novel elements, and to correct some previously assumed hypotheses on the scaffolding, thus improving the understanding of pre-industrial building maintenance technology