The Simon Community said the crisis is spiralling out of control as the use of hostels, hotels and B&Bs to house people is becoming the long-term solution.
Chief executive Sam McGuinness said every day the most vulnerable are being hit with a complex mix of housing shortages, soaring rents, inadequate allowances and discrimination against people on welfare.
“Recent talks about green shoots are not reaching the most vulnerable in our society, the majority of whom never experienced any benefits from the Celtic Tiger,” he said. “Sadly, the less fortunate have become have become more unfortunate.”
Dublin Simon is the latest in a line of charities, including Merchants Quay Ireland and The Peter McVerry Trust, which work with people sleeping rough, drug-users, and the homeless, to warn of the extent of the problem despite promises to end homelessness by 2016 only made last year.
Mr McGuinness warned that temporary accommodation was now becoming a long-term solution, with at least 50% of people who are seeking a permanent home now stuck in emergency shelters for more than six months.
Dublin Simon said a volunteer group counted 158 people on the streets on one night last week, 24% more than the official count last April. The charity said that figure does not include people classed as hidden homeless who are sleeping on sofas, staying in squats, in hospitals, hanging out in 24-hour internet cafes, or paying for B&Bs.
Mr McGuinness said a target set this year for 1,100 tenancies in Dublin has been slashed by one third.
“It is glaringly obvious that thousands of vulnerable and frightened people are being trapped in the revolving door of inadequate and insufficient emergency accommodation, forced to remain roofless,” he said.
“The longer people are forced to remain in emergency accommodation, the more intense supports they will need when they are lucky to have the opportunity to move on.”
Dublin Simon said its volunteers are also seeing a significant increase in the number of people bedded down in doorways, lanes and shop fronts in the inner city from Jervis St to Amien St and Harcourt St. Demand for sleeping bags increased by 57% in the year to the end of June.
Dublin Simon increased its housing capacity by 54% in Dublin, Wicklow, Kildare, and Meath in 2013.
Overall last year, the charity provided services to more than 3,000 people andits rough sleeper team made 4,241 outreach contacts.
It also supported drug-users with 3,284 emergency needle exchanges, a 31% increase on figures for 2012, and recorded a 20% increase in the number of people accessing treatment services.