How old and how exposed is the European building stock

How old the European stock is

The European Commission, through its civil protection knowledge network, reports that 80 per cent of the Union's current residential stock was built before the 1990s, and 40 per cent before the 1960s.

Exposure has grown far faster than population. Between 1975 and 2015 the population potentially exposed to earthquakes increased by 7 per cent, while the exposed built environment grew by 142 per cent. In 2015 around a quarter of the Union's population and around a quarter of its built-up area were potentially exposed to seismic scenarios with a 475-year return period.

The common reference for comparison between countries is the pair of European models developed within EFEHR: the ESHM20 hazard model and the ESRM20 risk model, which combines an exposure model of around 143 million buildings and around 460 million occupants across 44 countries with more than 500 vulnerability models.

The picture by country

The relevant threshold changes from country to country, because it depends on when each introduced a mandatory seismic code. The first-code column gives the year of introduction, and it should be read together with the shift to modern codes, which in several cases arrives decades later.

Why the date of the first code says less than it appears to

One element deserves attention before the table is read as a ranking.

The date on which a seismic code was introduced indicates when a rule entered into force. Effective protection of the building stock accrues when that rule reaches a modern performance level and is applied. In Italy 1974 marks the first national classification, and modern protection arrives with the 2003 ordinance and the technical construction standards of 2008 and 2018.

The same distance between formal adoption and effective protection recurs in other countries, and it is not confined to the past: the Turkish collapses of 2023 include buildings formally subject to a seismic code. It is the reason the table reports both pieces of information.

Where age and exposure combine

The combination of the two factors concentrates risk sharply. According to the European risk model, the average annual economic loss from earthquakes in Europe stands at around €7 billion, and almost 70 per cent of it accrues in Italy, Türkiye and Greece. The average annual loss of life is estimated at around 900, with over 75 per cent concentrated in Italy and Türkiye.

A 2023 study of the four countries with the largest expected losses finds that, out of a combined population of over 170 million across Italy, Türkiye, Greece and Romania, around 130 million people live in buildings designed with no seismic code or with low-level codes.

The highest-risk cities identified by the European model are Istanbul and Izmir in Türkiye, Catania and Naples in Italy, Bucharest in Romania and Athens in Greece. Zagreb, Tirana, Sofia, Lisbon, Brussels and Basel also show above-average risk, while cities such as Berlin, London and Paris sit at low values.

The two classes contributing most to losses, both economic and human, are low-rise unreinforced masonry, predominant in historic centres, and mid-rise reinforced concrete frames designed before modern codes, predominant in the urban areas of mainland Greece, Türkiye, Romania and Italy.

Italy in detail

Italy is one of the three countries in which almost 70 per cent of the European expected loss accrues, and its census data are among the most detailed available, which is why the picture there can be described at a level of resolution the comparative table cannot carry.

Around 60 per cent of Italian dwellings predate 1971, and over 56 per cent of the residential stock located in seismic zones 1 and 2 predates 1970.

Municipalities classified as high and medium-high hazard account for 36.2 per cent of the total and hold 41.3 per cent of the population. Around 21.5 million people live in high seismic risk zones, with around 12 million dwellings affected. In zone 1, the most hazardous, around 3 million people live in over 1.6 million dwellings, and Calabria is the most exposed region with around 1.2 million residents and 635,000 dwellings in that class.

In construction terms, the 2011 census records 57.2 per cent of residential buildings in masonry and 29.5 per cent in reinforced concrete. In terms of dwellings, floor area and population the two materials are equivalent, because reinforced concrete buildings have more storeys on average. In residential buildings located in seismic zone 1, masonry rises to two thirds.

The industrial stock

Industrial buildings in Italy number almost 991,000, of which around 213,000 are in seismic zone 1 and 778,000 in zone 2.

The Emilia earthquake of May 2012, with 28 fatalities and total damage above €13 billion, made the vulnerability of precast concrete industrial buildings evident. They were built predominantly between the 1960s and the 1990s in areas that seismic classification reached only in 2003. The principal cause of the collapses was the absence of effective connections between beams, columns and roof elements, with loss of seating and overturning of cladding panels. The law adopted after the event required works on the buildings that showed those deficiencies.

This segment has a characteristic that sets it apart from residential stock: seismic classification arrived after most of the stock was built, so vulnerability depends on construction period even more markedly.

What countries require for the existing stock

The picture of vulnerability assessment requirements, distinct from that of instrumentation requirements, varies.

Italy. Ordinance of the President of the Council of Ministers 3274 of 2003 introduced a mandatory seismic vulnerability assessment for buildings and works of strategic and public interest, both public and private, in every seismic zone, excluding works built or upgraded under the codes subsequent to 1984. The assessment is mandatory, and any resulting intervention remains subject to the availability of funds. The deadlines have passed: 31 December 2018 for zones 1 and 2, 31 December 2021 for school buildings in those zones, 31 December 2023 for completion of the assessments on nationally strategic buildings.

Türkiye. The 2018 code and the 2025 implementing directive make retrofitting mandatory for structures erected before 2000.

Portugal. Since 2019, seismic assessment of existing buildings has been mandatory in rehabilitation works.

European level. Part 3 of Eurocode 8 governs the assessment and retrofitting of existing buildings and is mandatory in Bulgaria, Cyprus, France, Portugal and Slovenia.