"Even China's population of 1.4 billion would not be enough to fill all the empty apartments littered across the country, a former official said on Saturday, in a rare public critique of the country's crisis-hit property market."

Now, housing gets old, people upgrade, so that supply will eventually be soaked up.

But the debt overhang on local governments and indivudal Chinese is the killer. They've built up several years of housing supply and now get to pay for it all while it stays empty for a few years - plus the value is dropping.

It's a massive drag on the economy as all that investment is locked up and unproductive.