Sinn Féin's housing spokesperson has called for "mandatory inspection and certification of all private rental properties".
The latest figures from the Department of Housing show that more than half of all private rental properties inspected last year did not initially meet legally enforced standards.
Overall a total of 37,800 did not meet the necessary standards, out of 62,085 properties inspected by local authorities last year.
Reacting to the figures, Eoin Ó Broin said that "not only did 60% of inspected properties fail to meet legally required minimum standards, but the level of inspection is low.
"There are 240,964 private rental tenancies registered with the RTB [Residential Tenancies Board], however we know many more tenancies are not registered," he said in a statement.
"While some council inspection levels are high, others are abysmally and unacceptable low.
"Today's figures demonstrate that the introduction of a mandatory inspection and certification regime for all private rental properties is now urgent.
Mr Ó Broin said the Government should ensure that 25% of all private rental stock is inspected and certified every year.
Landlords should also be required to display their certificate of compliance when advertising rental properties, he added.
Under the Housing Regulations Act of 2019, all private rental properties on the market in Ireland must meet strict standards for heating, ventilation, natural light, fire safety, electricity and sanitary facilities.
Among the worst affected areas were the four Dublin local authorities of Fingal County Council (3,768), South Dublin County Council (3,594), Dublin City Council (3,209) and Dún Laoghaire-Rathdown County Council (2,961).
They were followed by Meath County Council (2,692), Cork City Council (2,669), Cork County Council (2,208), Waterford City and County Council (1,735), Louth County Council (1,582), Kildare County Council (1,421), Limerick City and County Council (1,365) and Mayo County Council (1,241).
The figures also show that 2,330 formal improvement notices against landlords to order them to make changes to the properties were also served, more than half of which (1,274) were for properties based in Dublin City Council, with Sligo County Council the next highest at 554 properties.
A total of 210 "prohibition notices", which legally bar someone from renting out a property to renters, were also issued last year including 148 in Dublin City Council, 13 in Kildare County Council and 11 in Wicklow County Council.
In addition, ten legal cases were initiated by local authorities, including cases relating to properties in Donegal County Council, Dublin City Council, Wicklow County Council and Dún Laoghaire-Rathdown County Council.
The figures follow a similar trend in recent years, with figures released by the Department of Housing showing more than half of properties have failed to meet necessary standards on first inspection every year since 2012.
However, last year did see the most inspections ever conducted, with the 62,085 properties inspected a total of 80,151 times as some were inspected on more than one occasion.
This figure compares to 63,567 inspections in 2023; 40,308 in 2019 and an average of 20,000 a year between 2005 and 2017.
In a statement, Minister for Housing and Fianna Fáil TD James Browne said: "Ensuring that private rented accommodation regardless of what town, city or rural area you're renting meets required standards is incredibly important.
"We want to ensure that rental tenants are afforded standards which ensure requirements such as adequate heating, ventilation, sanitation, and fire safety measures are met.
"It's the basics, and it is what renters should be able to expect from every landlord," the minister added.
The full annual figures breakdown can be read here.
