Germany is suffering an affordable-housing crisis. According to Hans-Böckler-Stiftung, a trade-union foundation, the country’s big cities lack 1.9m reasonably priced homes. Berlin tops the list with a shortfall of 310,000, followed by Hamburg and Cologne. Some 40% of households in German cities spend at least 30% of their net income on their rent. Today politicians, including Chancellor Angela Merkel, will meet with representatives from building firms, trade unions and tenant associations for a “housing summit”. One issue is social housing. Ten years ago Germany had 2m social homes, against 1.2m today. So the government will pay an extra €1.5bn ($1.8bn) a year into states’ social-housing schemes. But cities continue to swell, raw materials are getting dearer and labour is in short supply. Meeting the target of 1.5m new homes by October 2021 will take a sense of urgency. Mrs Merkel’s governments have shown little of that of late.