Roofing in Vatican City

Vatican City is the world's smallest independent state, covering about 44 hectares (109 acres) in the centre of Rome. The whole state is a UNESCO World Heritage site, and its roofing story is dominated by one structure: the dome of St Peter's Basilica, one of the largest masonry domes ever built.

Climate and hazards

The Vatican shares Rome's Mediterranean climate, with hot, dry summers and mild, wet winters. Its main roof-related hazards are ageing masonry and timber in historic buildings and the cracking of the great dome, which has needed iron reinforcement since the 18th century.

Roofing history

An earlier basilica founded by Constantine in the 4th century stood over the tomb of St Peter; its remains lie beneath the present church. The new basilica was begun on 18 April 1506, and the Fabbrica di San Pietro, the body that still maintains it, was founded the same year. The church was consecrated by Pope Urban VIII on 18 November 1626. Its builders included Bramante, Raphael, Michelangelo, Della Porta, Maderno and Bernini.

The Apostolic (Vatican) Palace grew from a structure built by Nicholas III in 1277-1280 and was enlarged from the 15th to the 17th centuries. Its chapels are famous for their ceilings rather than their roofs: Michelangelo painted the Sistine Chapel ceiling frescoes and the Last Judgement.

The dome of St Peter's

• Design: Donato Bramante drew the first design in 1506; Michelangelo redesigned the dome from 1547.
• Completion: Giacomo della Porta and Domenico Fontana completed the dome in 1590, the last year of the reign of Pope Sixtus V. Fontana finished the lantern under Pope Gregory XIV.
• Structure: two shells of brick, the outer one strengthened by 16 stone ribs.
• Size: about 136.57 m (448.1 ft) from the floor to the top of the external cross, with an internal diameter of about 41.47 m (136.1 ft), slightly smaller than the Pantheon and Florence Cathedral.
• Reinforcement: after cracks appeared, four iron chains were installed between the two shells in the mid-18th century; as many as ten chains have been fitted at various times.

Traditional and vernacular roofs

As a city-state within Rome, the Vatican has no separate vernacular tradition; its older buildings follow Roman practice of timber roofs with clay tile coverings and masonry vaults.

Roofing today

Roof work in the Vatican is primarily conservation of historic fabric, carried out under the Fabbrica di San Pietro for the basilica.

Codes, standards and regulation

No source on Vatican building regulation was located.

Industry

There is no roofing industry in Vatican City.

Notable roofs

• Dome of St Peter's Basilica (1590)
• Roofs and vaults of the Apostolic Palace and Sistine Chapel

Sources and gaps

Seismic and climate data for Vatican roofs, data on materials and contractors, details of the external covering of St Peter's dome and of modern conservation methods were not found in published sources.