In 2024, Tallinn's Environment and Public Works Department carried out a small-scale study to determine whether buildings in Tallinn's Old Town are subsiding and, if so, what is causing it. As the study did not produce definitive conclusions, further work is needed to identify the causes.

"We have identified more than 20 buildings where there have been signs that the structures have been damaged for one reason or another. Considering the number of buildings in the Old Town, that's quite a large number and there could actually be more. The conclusion is that they require fairly extensive reconstruction work, so it is certainly a significant expense for property owners," said Toomas Haidak, head of the department's development and planning service.

There are several possible reasons why buildings in the Old Town are subsiding. One suspected cause is spring water flowing downhill from Toompea into the lower town.

"There have historically been springs on Toompea and the water flows downhill toward the sea. Naturally, the area between Pikk and Lai streets forms something like a bowl, so the water collects there. If it cannot continue flowing, it creates significant structural problems for the buildings. Cracks and the risk of partial collapses are a reality today," said Toomas Oosalu, a member of the Old Town Society.

However, the water's path is not random but is shaped by historic drainage systems that may no longer be functioning properly.

"Historically, water from Toompea was channeled into shafts and pipes. The concern now is that we do not know what condition those shafts are in or whether they still work. They may have been damaged during the many construction projects carried out over the years," he added.

In addition to spring water, Old Town buildings and streets are also affected by possible water main leaks and rainfall.

"If a leak or stormwater gets beneath the street, it washes away the underlying layers, which can in turn lead to structural problems for buildings. We can already see sections of streets subsiding," said Kaire Tooming, Old Town development coordinator.

The subsidence issue also raises questions about building maintenance.

"A considerable number of subsidence cases are linked to deferred maintenance or inadequate upkeep of buildings," Tooming said.

Because severe subsidence requires extensive restoration work, addressing the problem is a long and time-consuming process.

According to Haidak, the length of the process is also due to another factor.

"The process may be lengthy because there is no clearly defined party responsible for this issue. Generally, the condition of a building is the responsibility of its owner. But if the damage is caused by factors beyond the owner's control, then the owner does not really have anyone they can turn to who is responsible for addressing the issue more broadly," Haidak said.

In the coming months, the Environment and Public Works Department plans to launch an additional innovation project to analyze whether changes over time can also be detected using satellite imagery.

--

Follow ERR News on Facebook and X and never miss an update!