A national rescue programme is needed to assist more than 400,000 property owners whose buildings are sinking, according to a government advice body.

At a press launch of a major report into the scale of the problem and what must be done, the RLI environment and infrastructure agency said the situation is now urgent. It criticised homeowners, mortgage lenders, government and insurers in no uncertain terms for “looking away” for 20 years.

Jantien Kriens, deputy chair of the RLI, said that a national plan is desperately needed because it is now evident that climate change – lower water tables, hot summers drying the ground, different patterns of rainfall – is making the Dutch property subsidence problem worse.

“It’s not just a financial problem, although it is certainly a financial problem because the owners of these buildings will have to find a chunky €50 billion at some point,” she said.

“It’s not just a technical problem but it is a technical problem too because we don’t yet have the capacity to work in all kinds of innovative ways on foundations problems. But it’s also a social problem because that house where you should feel safe is no longer safe.”

She said that the housing market – which has seen property prices double since 2015, based on scarcity and a period of cheap loans – is simply not functioning, partly because people have wilfully ignored the true state of many buildings. The body estimates at least 6% of Dutch buildings have a problem.

“Now we have a market that actually doesn’t function properly, because not the sellers, not the buyers, not the estate agents or the banks know what is going on under the ground and the consequences for selling your house or buying a house,” she added. “In a scarce housing market, maybe you just want to buy something and you don’t want to know what is happening underneath it.

“And so, together, we have ensured that for 20 years we kept a problem underground that we knew at some point had to come onto the table. But it didn’t because apparently nobody had an interest in factoring it into the price of the home.”

The RLI, which was asked to give advice by De Jonge last year, says although much is unknown, initial indications suggest that at least 425,000 buildings have a “reasonable to serious” current foundation problem and another 400,000 could develop in future.

The reason is that piles underpinning properties can start to rot or be attacked by bacteria, for instance if the water table drops and wooden piles dry out. Unstable foundations lead to splits in frontages, floors and ceilings, doors and windows that don’t fit, floors that fall away and characteristic zig-zag cracks in brickwork around windows. Severe problems can mean homes are can’t be lived in and a foundations restoration can typically cost €120,000.

Subsidies

The body proposes a national foundations drive by the government, so that not only property owners are responsible for the costs of repair. By 2029, it proposes, every house seller should be required to declare the state of their foundations.

In the meantime, it proposes a 90% subsidy for foundations investigations and a 30% subsidy for repair work, which may also add value to properties if it can increase the available basement space. There needs to be prevention work to monitor ground water levels, a single information point for owners and renters, a €12 billion pot for subsidies plus plan for loans, and scale-up of capacity in the foundations repair industry, the agency said.

Housing minister Hugo de Jonge said in response to the report that government needed to step up so that not only home owners were financially responsible. “Houses where the foundations damage has taken place are houses that belong to someone so the owner is responsible,” he said.

“But you can’t leave it there. So if it’s not just the current owner who needs to take action, who does? It’s not just the government, but maybe also mortgage lenders, insurers: we want to get everyone to the table.”

Infrastructure minister Mark Harbers pointed out that subsidence also affects roads and other infrastructure, and both ministers said it was an urgent task for the next government, although a start needs to be made now.

Drinks

A recent Oxford Economics report found the Dutch housing market was one of the most overpriced compared with salaries in Europe last year, despite the fact that it is not the only place with a pressing housing shortage.

The AFM financial authority has estimated 800,000 homes, one in 10 of the stock, are at risk of subsidence. Last autumn it recommended that ‘climate risks’ such as foundations problems and flooding potential – which is uninsurable in the Netherlands – should be factored into house prices to protect lenders from risky loans and owners from impossible costs, through a ‘climate label’. Property valuation company Calcasa has suggested that this could reduce the value of the total market by 10%.

After a year of falls, annual house prices have risen Netherlands over the past two months.