Donegal has the highest number of holiday homes in the country, with over 11,300, 13% of the national total.
That's followed by Kerry with 11% and Wexford at 10%.
The latest GeoView report from Geodirectory shows Leitrim had the highest proportion of vacant dwellings, at 21%, followed by Roscommon at 18% and Mayo 17%. Donegal, Sligo and Cavan all have vacancy rates of 15%.
According to the report, 285 new addresses were added in Donegal in 2016, representing 2.8% of the national total.
There were 188 buildings under construction in the county during the third quarter of last year, 3.8% of the national total, while 282 residential units commenced between January and October, 2.8% of the national total.