One in five people in Ireland is spending 40% or more of their wages on rent.
Social Justice Ireland says it is concerning given the increasing numbers of people renting.
A study by the organisation suggests one in ten people pay over 60% of disposable income on rent.
The study also found that 12.6% of the population, 611,982 people, were living in substandard conditions in 2017.
Michelle Murphy, a research and policy analyst at Social Justice Ireland, says it is unlikely a significant number of current renters will own their own homes in the future.
"It's something we should be concerned about because, obviously, more and more people are renting," she said.
"You have one-in-10 people in this country who are paying over 60% of their disposable income in housing costs. These are people who are in the private rented market."
Social Justice Ireland's report compares major issues facing Ireland and the EU as we head towards European Elections this May.
The independent think tank compares a range of policy issues from an Irish and European perspective and considers what we need to change for the future.
Director Sean Healy says we need to move away from prioritising economic growth over everything else.
"We're looking at a situation where a more integrated approach to policy is required, that in fact we need to face up to a failure we've experienced as a society and as a union over the past couple of decades where we have basically followed the idea that economic growth would lead to everything else being dealt with in due course."
Read the full report here: