There is a warning it could take four decades to clear the almost 20,000 people waiting for a house in Dublin city.
Between July 2014 and December last year the number of homeless families in the capital increased by 289 %.
The Government is being urged to take radical action to prevent the situation getting any worse.
Dr Rory Hearne from Maynooth University says the homeless issue is just one part of the crisis.
"We're seeing this, what I call a kind of generational inequality between the generations who are under 40, are basically not able to buy housing.
"It's not there, they can't afford it, they can't get mortgages, and they are stuck in a private rented sector which is unsecure, which is extremely costly," he said.