Rents have more than doubled in the past decade.
In 2011, the average rent nationally was around €742 per month compared to an average of €1,415 in the final quarter of last year.
New figures from the Residential Tenancies Board show rent went up in every county except Kildare, with the most expensive rates found in Dublin where tenants are paying just under €2,000 every month.
Assistant Professor of Social Policy at Maynooth University, Rory Hearne says the problem lies in supply.
"The new supply coming in the private market is really expensive, the build to rent properties which are coming in at €2,000 a month which is driving up these average rents.
"The problem does come back to the failure year after year of Government to build affordable social housing, or sufficient cost rental housing which is affordable rental."
