In regard to internal migration, the trends on which the need for about 1,000 dwellings a year on account of internal migration are based are derived from censuses and returns by local authorities, who were asked to take into account information derived from local inspections, trends in applications for houses, needs arising from industrialisation, etc. An allowance is made in the White Paper estimate for duplication with needs arising from other causes.
The estimate of the increase in the number of married couples living in the country—which is not the same as the increase in the number of marriages to which the Deputy refers—is based on a series of population projections by the Central Statistics Office described in appendix D of the Third Programme for Economic Expansion.
The estimate of an effective need of about 10,000 dwellings for persons in the 24,600 households approximately comprising more than one family unit is based on the assumption, supported by the rate of application for dower house grants, that the effective need for separate accommodation for households engaged in agriculture is small and that more than one out of every two of the families in the remaining households would require separate accommodation.
The basic data for the estimate of about 15,000 families living in severely overcrowded dwellings with not more than four rooms are local authority returns, the interim results of the census of population 1966, as published in the June, 1968, issue of the Irish Statistical Bulletin, with an allowance for duplication as between needs included under other heads and for houses provided since the census was taken for persons living in overcrowded conditions.
Most of the overcrowded dwellings with four or more rooms are privately owned. A decision to extend is, therefore, a matter for the individual occupier or owner. In view of this no separate estimate was made of the period within which extensions would be carried out or of the cost. In recent years about 10,000 dwellings a year have been substantially reconstructed with State aid.
In conclusion, I may say that the aggregate forecasts of housing output arrived at in the White Paper are supported by a number of other independent and expert assessments of which I am aware, including that at paragraph 518 of the Buchanan Report.