Under-supplying housing in a market that already is under-supplied means prices will not come down, a former chairman of the Land Development Agency has warned.
John Moran, who is also a former secretary-general at the Department of Finance, was commenting on the Government's Housing for All plan.
The €4bn per year plan pledges that 300,000 new homes will be built between now and 2030 - that includes 90,000 social homes and 54,000 affordable homes.
Mr Moran told On The Record the Government has to convince the market it can do this.
"At the beginning of the Land Development Agency when we were trying to work out how much cost-rental we needed to deliver, we reckoned there were 300,000 people renting in Ireland.
"And many of those are renting in either too expensively, or in ways that they don't really want to have a sustainable home going forward.
"So for us, the need in cost-rental may have been as much as - certainly over - 100,000 homes or people would be buying those homes, whichever.
"So it really seems from the analysis that we did... since they're coming down in somewhat the same place it just is concerning.
"If you have an under-supply going into a market that already is under-supplied, prices will not come down.
"And in order to get affordability in Ireland, it's a hard reality for most of us - who are homeowners across the country - that the reality is is that Irish prices of houses had to go down.
"And that is going to mean people's assets being worth less, and some of the banks are going to have to be sure about their mortgages and things like that.
"But if we don't get that done - and the only way to do that is to suggest convincingly to the market that the Government, if the market doesn't deliver enough houses, will do it themselves.
'A fair price'
He says the only way house prices will fall is if you have enough houses for those that want them.
"During the crisis, what was happening was banks were lending based on the value of homes - and so of course as houses kept going up they kept lending more money.
"What you saw though - if you look a couple of years later - once the crisis hit and our population started going down, actually all of a sudden the extra supply of rental income in Dublin meant that rents went down by something like 50%.
"So it does work - the trick however is that... you have to find a way to make the market able only to take a fair price.
"And the only way you will do that is to have enough homes available so that everybody has one.
"As soon as you lose that dynamic, and we are very much out of equilibrium at the moment, what happens is that the people who have the most money tend to go after the short supply of housing - driving the pries up.
"Because actually they have higher incomes than the average - and so they drive the price of housing up above what the ordinary, average person can ever afford, unless there's so many homes that they stop buying or renting".
While Sinn Féin's housing spokesperson, Eoin Ó Broin, says the majority of the housing plan is 'padding'.
He told Pat Kenny on Friday: "The vast majority of the 160 pages are padding, but when you actually scratch beneath the kind of bloated figures that have been used in the press conference yesterday and you look at the actual delivery - particularly of affordable homes over the coming years.
"This plan is deeply disappointing - next year we're only going to get, at the very top end, 2,000 genuinely affordable homes.
"We might get 3,000-3,500 the year after, and threonin it'll hit about 4,000.
"That's nowhere close to the level of need that people desperately seeking to buy their own home - or those people stuck with very high rents out there - are looking for.
"And likewise for renters, there really is nothing new.
"The claim that they're going to introduce tenancies of indefinite duration is misleading, there's nothing to stop rising rents".