Mayo tops national list as Ireland’s most derelict county

Mayo has been officially ranked as Ireland’s most derelict county, according to the latest figures published this week by GeoDirectory.

The data, which tracks residential dereliction nationwide, shows that as of the second quarter of 2025, there were 19,821 derelict units across the country – a 2.9% decrease on the same period last year.

Despite the overall decline, Mayo continues to record the highest concentration of derelict properties in the State, accounting for 14.1% of the national total.

Donegal (11.5%) and Galway (8.9%) were next on the list, underlining the ongoing issue of vacant and deteriorating housing stock along the western seaboard.

Connaught had the highest share of dereliction of any province, with 7,567 units, representing 38.2% of the national total.

By contrast, Ulster recorded the lowest share, at 3,159 units (15.9%).

A property is deemed derelict when significant structural work or reconstruction is required before it can be re-occupied.

In many cases, such buildings have remained unused for years.