In a leafy neighborhood in Dusseldorf, Milena and Manuel David planned to break ground this summer on a new home, a milestone that was going to get them out of a cramped apartment where they share a bedroom with their two kids.

But during the 16-month wait for a permit, mortgage rates had tripled and their building costs rose by €85,000 ($90,000). The couple crunched the numbers again before facing the fact that their dream of building their own home had collapsed as part of Europe’s worst construction crisis in decades.