Census 2016 highlights extent of Ireland's housing shortage
The CSO figures also show a quarter of sales past year were to first time buyers.
Among larger towns (population of 10,000 or more) Letterkenny (14.9pc), Longford (14.6pc) and Ballina (14.3pc) ranked highest in terms of vacancy.
Nationally, by the age of 35, more people own their own home than rent, compared with age 32 in 2011.
This age has steadily crept up over the past quarter of a century, with an equivalent age of 26 in 1991.
The figures from the CSO also show that Offaly's housing stock fell to 30,740 in April 2016 from 30,750 in April 2011, a decrease of 0.03%. The Central Statistics Office (CSO) also counted 62,148 vacant holiday homes.
The highest growth in rent was in Dublin city, which increased by nearly 30% while rises in excess of 20% were also recorded in Dún Laoghaire-Rathdown, Fingal, South Dublin and Kildare.
Nearly 10% of the population in accommodation with less than one room per person: There were 95,013 permanent households with more persons than rooms, at an average of 4.7 persons per household.
Within the Dublin City local authority area, apartments (74,537) were the main dwelling type for the first time replacing terraced houses (74,446).
It recorded that 14,932 homes were finished for the market last year but experts warned that might include homes that have been empty for two years and require a reconnection to the electricity network.
"We need action to get the vacant homes that are suitable back into the active housing stock as urgently as possible". Many of these people are the "hidden homeless"; those thousands of families in Ireland who are living in substandard, overcrowded or unsafe accommodation, unable to move or demand better accommodation because they have no other options.
Roughan Mac Namara of Focus Ireland criticised what he called a "series of halfway-house policies" by successive governments.
The "devastating" scale of the State's housing crisis has been exposed by new figures, charities in the homelessness sector said on Thursday.