The initial pipeline of development under the Government's new housing plan will provide just 10,000 homes - and the first won't be delivered until 2020.
It promised that the new €1.25bn Land Development Agency (LDA) will deliver 150,000 homes in the next two decades.
Current estimates on the number of new homes needed to meet demand stands at as much as 35,000 per year.
Taoiseach Leo Varadkar defended the plan and its timescale, saying: "If this was the only thing we were doing, it would be legitimate criticism, but it's not."
He pointed to other measures being taken under the Rebuilding Ireland initiative and how up to 20,000 homes will be built this year.
He said the LDA would accelerate new home building "so that we reach that magic figure of somewhere between 30,000 and 35,000".
Mr Varadkar was joined by a host of ministers to launch the new agency, which he said would come to be seen to be as significant as the ESB, Aer Lingus or the IDA.
The plan has already faced criticism. Labour TD Jan O'Sullivan and People Before Profit TD Richard Boyd Barrett criticised the scheme, claiming it amounted to privatisation of public land.
Mr Varadkar dismissed such criticisms as "ideological" rather than being "concerned about the interests of real people".
Fianna Fáil TD Darragh O'Brien claimed that the Government's repeated announcement of housing plans were causing "fatigue" among people seeking homes.
The LDA has been tasked with managing State-owned land to facilitate developments in which at least 40pc of the units are social and affordable housing.
It has start-up funding of €20m, an interim chief executive in former Nama chief financial officer John Coleman, and an initial site list to provide more than 3,000 homes. The LDA is in discussions with State agencies for land that could yield another 7,000.
The agency is a commercial organisation and will provide land for residential development either by the State or in joint ventures with developers. There will be a requirement that at least 30pc of developments are affordable homes and 10pc are social housing.
As part of her criticism, Ms O'Sullivan said there was "no clarity on what they mean by affordable".
Housing Minister Eoghan Murphy said affordability was defined as someone paying no more than a third of their income on mortgage repayments.
He said that existing schemes cater for individuals earning up to €50,000 and couples on a combined €75,000 with house price caps of €320,000 in the Greater Dublin Area and €250,000 elsewhere.
He said: "We'll be working on those types of affordability requirements".