Tenants are paying more than €2,000 extra a year on average in rents, putting homeownership even further out of reach for thousands of families.
The latest Daft.ie quarterly report shows rental payments have soared by 14% nationwide in the space of 12 months, the largest increase on record.
The soaring costs have been blamed on a chronic shortage of rental accommodation, with just 1,087 homes available to rent on November 1, down a quarter on the same date a year ago.
Coming in the midst of higher mortgage interest rates and more stringent lending criteria from banks, the news has been described as the "worst possible combination" for those desperately trying to get a foot on the property ladder.
Trinity College professor Ronan Lyons, the author of the property website's report, warned the country is entering "uncharted territory" in the rental sector.
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"What has happened over the last 18 months has been an extraordinary collapse in the stock available to rent," he said.
"The total number of rental homes put on the market nationally has fallen steadily over the last decade.
"In 2016, there were about 75,000 homes put up for rent over the course of the year. By early 2022, that had fallen to less than 50,000, and in the last six months, it has fallen again to about 35,000."
The average monthly rent a year ago of €1,516 has ballooned to €1,698 and is more than double the low of €765 per month in late 2011.
The annual inflation rate of 14.1% is the highest ever recorded by Daft.ie since its launch in 2006.
That includes a 4.2% increase between June and September period this year.
"That is the single largest quarterly increase ever recorded in the rental report in a series that goes back to the start of 2006," said Lyons. "Until this latest report, the largest quarterly increase had been 3.4%." d.
Housing campaigner David Hall, of the Irish Mortgage Holders Organisation, said that renters' problems have been compounded by rising interest rates and more stringent lending rules.
Finance minister Paschal Donohoe ignored warnings from his officials that the €500 rent credit introduced in the budget would push up rates for those outside rent pressure zones.
The minister said that he recognised there were risks in going ahead with the rent tax credit, but there were also risks in "not going ahead with it".
Mike Allen, of the homelessness charity Focus Ireland, said many landlords had been frightened out of the market by government measures, such as the winter eviction ban and the proposed introduction of unlimited tenancies.
Rents rose in Dublin by 14.3% while in Cork city the annual change was 12.1%, in both cases higher than three months ago.
Since the introduction of rent pressure zones in 2016, the rents of sitting tenants have increased by 17% on average, compared to an average increase in open market rents of nearly 75% over the same period.
