Housing New Zealand tenants in a complex in central Christchurch have been given 90 days to leave, because the flats meet only 12% of the building code.
Between 50 - 60 people live in the Gloucester Street flats.
Housing New Zealand staff visited the tenants as soon as they found out the building was unsafe following an engineering report last week.
The agency has been assessing all its stock to make sure none are below 67% of the code. The Gloucester Street complex was one of the last to be checked.