The Central Statistics Office has explained the discrepancy between its figures on the number of new houses built and the Department of Housing's figures at an Oireachtas committee.
The CSO's Census figures published in recent weeks showed Ireland's housing stock increased by 8,800 units between 2011 and 2016, a rise of just 0.4%, with 33,000 householders indicating their home had been built in the previous five years.
Sinn Féin housing spokesperson Eoin Ó Broin asked senior statisticians from the CSO to explain the difference between the census figure of 33,000 new builds, compared to the Department of Housing figure of 50,000.
Director General of the CSO Pádraig Dalton said the 33,000 figure excluded vacant dwellings that would have been built during the same period.
Mr Dalton said while he could not comment specifically on the department's figures, he said there were 114,000 households in the Census who did not give information on when the house was built.
"It would be naive of us to assume that none of those houses were built between 2011 and 2016," Mr Dalton said.
The CSO figures also showed 245,460 vacant dwellings, of which 62,148 were categorised as holiday homes.
Senator Victor Boyhan said the figure of 36,000 vacant dwellings in Dublin was 'staggering'.
"In real terms that's around 10% of the housing stock," Senator Boyhan said.
Fine Gael TD Fergus O'Dowd said London had 20,000 vacant homes, or around 3%, a much lower rate than Dublin.
Mr Ó Broin also raised the numbers of overcrowded houses recorded in the latest figures.
"For me one of the most startling revelation in the figures was the overcrowding, almost 10% of the population with homes with more persons than rooms," he said.
Senior statistician Deirdre Cullen said the figures also showed cities growing faster than counties, with strong evidence of rural-urban divide.
Meanwhile, Minister for Housing Simon Coveney has said compulsory purchase orders are not going to solve the problem of a lack of supply in the housing market.
Speaking on RTÉ's Today with Sean O'Rourke, Mr Coveney said such orders are legally challenging and will spend time stuck in the courts rather than bringing more properties on to the market.
He said incentives are needed to encourage owners to make their properties available for the rental market, and that such incentives will be included in a detailed Government strategy in the next couple of weeks.
Mr Coveney said rent pressure zones are essential to ensure that pressure on families can be kept to a minimum.
He said the restrictions on landlords to increase rent by no more than 4% a year offers such certainty.
He added that the success of introducing rental pressure zones can be easily seen - the rate of rental inflation has dramatically slowed in the first quarter of the year when compared to the same period last year.
Mr Coveney said he would like further incentives offered to commercial property owners to make the top floor (over the shop) properties available for rent.
He said this will also be included in the Government vacant property strategy to be introduced in the coming weeks.
There are currently five times as many properties available to rent on AirBnB than on Daft.ie, Mr Coveney said, and if his department does not receive a satisfactory Memorandum of Understanding from AirBnB, he will introduce legislation to restrict the usage for long-term rentals.
He said the company must make it clear to their users what their ethos is, and that it is not a mechanism for renting in the long-term.
"I think AirBnB is a good addition to the market on one level. It allows lots of people to get some extra income by leasing out their properties for a couple of weeks a year.
"But I've made it very clear to AirBnB that if we don't get a satisfactory Memorandum of Understanding from AirBnB in terms of what information they provide to their clients that we will introduce legislation to make that happen."
