A Construction bubble has fuelled the economic growth in China over the last 15 years in the same way it has in Ireland and Spain since the Euro and as it did in Japan in the eighties. When the bubble bursts, it will hurt.
The prices of houses in China have already reached a peak and have now started to go down. In response buyers will delay purchasing in the expectation that prices will go down further. This will become a self-fulfilling prophecy if sellers cannot pay the cost anymore and have to reduce prices to find buyers.
Dropping prices will be a strong incentive for construction companies to stop building, also because there already is a large reservoir of unsold houses in China. Construction is 10% of the Chinese economy (acc Mr. Wei Yao of Societe Generale). In addition, following a dip in construction all supplying industries will loose turnover (for many a substantial part of their existence). Especially the upstream companies, at the beginning of the supply chains, will see a significant dip because the whole chain will de-stock. This supplying industry is a much bigger part of the economy than the 10% mentioned by SG.
Dropping prices will also give strain on the banking system if the value of the houses drops lower than the mortgages. A Chinese banking crisis will be felt throughout the world. And dropping housing prices will reduce Chinese end market consumption, affecting all other industries as well.
The Chinese government might want to keep their trillion in the pocket to solve these problems, in stead of investing it in Greece or Italy.
The only consolation is that housing prices in China have gone so high that many ordinary people cannot afford a house. So if the prices drop 50%, a whole new market may emerge.