The past few years appreciation is mainly due to asset inflation because of US dollar, speculation by Chinese from China, and government push to increase population by a huge amount. HDB prices provide a bottom for private housing. This effect kicks in only during a recession, in a booming economy other factors as mentioned earlier is more influencing. In Singapore, home ownership is over 90%, many of us buy private housing for rentals (to foreigners) and stay in cheap subsidized HDBs. Government has begun to stop this trick because the other 10% miss the opportunity and the aspiring middle class (degree holders) are alarmed that the prices of private housing is appreciating very fast. The degree holders want to have the cake (stay in HDB) and eat the pie (rent out private housing) too, after 5 years in HDB, fast rising prices mean they are unlikely to eat it.