THE IRON ROOF OF THE MILAN GALLERY “VITTORIO EMANUELE II”: HISTORIC IMPORTANCE AND PAST MAINTENANCE FOR ADEQUATE FUTURE INTERVENTIONS

Iva Stoyanova

Politecnico di Milano, via E. Bonardi 3 20133 MI, iva.stoyanova@polimi.it

ABSTRACT

This paper introduces into the historic importance of the glazed iron roof of the Milan Gallery as an emblematic example of 19th-century iron-glass architecture. The existing knowledge is complemented with highlights on the joint system for lateral thrust management and the cruciform glazing bars supporting the maintenance facilities as two significant examples of the structural adoption of iron. Then, the paper discusses the historical interventions in the iron roof as surface treatment from the first (1907) to the latest (1981-89) maintenance campaign commonly involving mechanical cleaning, anti-corrosion coatings and oil-based paints. Special attention is given to the post-war interventions which varied from conservation, repair works and reconstruction of primary iron elements to the substitution of the entire glazed canopy. The canopy reconstruction is discussed as an intervention which introduced improvements in the original glazing technology. The latest conservation campaign is deepened in view of the material failure and compromised static behaviour of the 19-century structures. Finally, the roof today is concluded to be a unity of ferrous materials and techniques dating back to different historical periods which efficient co-existence is menaced by the alarmingly under-maintained state. The lack of up-to-date information necessitates further onsite investigations, appropriate laboratory tests and adequate simulations of the roof structural behaviour.

Parole chiave/Key-words:

Iron-glass, Conservation, Anti-corrosion, Kruptite, Piatti-Clerici