Housing New Zealand acknowledges it is difficult for young people to find a place to live in Christchurch following the earthquakes and says they are often given priority for state housing.
Christchurch charity St John of God Hauora Trust says the lack of housing for vulnerable young people in the city is now a serious public health issue.
Trust programme manager Paul McMahon says that before the earthquakes more than 1400 young people were identified as living in inappropriate and insecure housing, and the situation is now much worse.
He says among those affected are young sole mothers with children who are forced to either share cold, damp homes with others or live in unsafe domestic situations with relatives. Young people who have emerged from state care are also hit by the accommodation shortage.
Mr McMahon says he knows of one group living in a seriously mould-infested house since the February 2011 earthquake.
He says Housing New Zealand is beginning to recognise the problem but much more needs to be done.
Housing New Zealand manager of tenancy services Symon Leggett says it is working to increase affordable housing in the city by replenishing some of its own stock and with non-government providers.
Mr Leggett says young people and young families make up a large portion of those who are given priority for state housing in the city.
Symon Leggett says those on the waiting list are offered temporary affordable accommodation.
About 500 state houses are still uninhabitable, and the agency does not know how many of those will be repaired.
It has completed repairs to 212 earthquake-damaged homes in Christchurch within its target of six months and plans to build between 200 and 350 new houses on land it owns around Christchurch.