A draft report has found that 85% of flats in Dublin involved in a crackdown on poor housing do not meet minimum housing standards.
The report was carried out by Dublin City Council and the Royal Institute of Architects of Ireland.
It found the majority of flats in homes built before 1963 did not meet basic housing standards, and that a two-tier system has developed between new apartments and older flats.
One of the authors of the report, Paul Kelly from the Royal Institute of Architects of Ireland, says the results are shocking.
"There roughly 94, 95 standards that apply to general housing - and there are 14 that apply to general housing that I'm talking about, pre '63 flats," he said.
"And then Dublin City Council's inspection would have found that 84, 85% of flats did not even comply with the 14 or 15 standards applicable to them.
"So, you're looking at a pretty low standard not even bring met by an awful lot of this type of housing."