Former Minister Pat Rabbitte has criticised those responsible for letting the sub-standard accommodation.
Dublin City Council says it will be reviewing reports of fire risks and overcrowding in rental properties when it meets on Monday.
Pat Rabbitte said that the uncovering of slum-like properties is astonishing.
“If there are companies or whatever behind those terrible conditions, I think they’re guilty, potentially, of corporate manslaughter,” he said.
“There ought to be an improvement in the law. This is no common-or-garden breach in regulations.”
Dublin Fire Brigade is investigating 25 private rental properties specifically reported to the service,.
Confirmation came after three rental properties in the capital were exposed by RTÉ Investigates for health and safety risks and overcrowding.
"It actually felt like living in a submarine" - RTÉ Investigates: Nightmare to Let | RTÉ One tonight 9.35pm | pic.twitter.com/9F0GNw3HR9— RTÉ News (@rtenews) November 2, 2017
The fire brigade’s convenor Shane McGill, said: “It is clear that the fire risks in cities, in particular, have changed substantially and the fire service needs to respond accordingly.
“We are now dealing with multi-occupancy dwellings the likes of which have not been seen since the time of the tenements. As shown in the programme, there are many people living in these overcrowded and clearly unsafe units.”
Mr McGill said: “Adding to the problem is a large amount of combustible material evident in these dwellings. In addition, height restrictions have also been lifted on building in the city, which will lead to more high rise.”
Meanwhile, Siptu’s national full-time firefighters chair Noel Heaney said operational fire prevention staffing numbers had not increased since the outcome of the Stardust fire enquiry.
“They urgently need to be increased in order to conduct fire safety inspections of buildings,” he said, urging Housing MinisterEoghan Murphy to intervene.
Brendan Kenny, deputy CEO of Dublin City Council, said the fire service was dealing with 25 locations. “There was a very serious case in Mountjoy Square that was dealt with and closed down. There are other cases out there,” he said.
“We need to get a clear, clear message out to these unscrupulous landlords that we won’t tolerate this in the future,” he said yesterday.
Mr Kenny said gross overcrowding is a new trend: “This is a new situation that we have faced in about the last 12 months, an increasing level of gross overcrowding in the private rented sector.
“Initially, we were trying to deal with it through environmental health and planning enforcement. It has become clear the only way to deal with these issues is through the fire brigade and fire safety and that’s what we have been doing,” he said.
In one case highlighted in the broadcast, a private rented property occupied by 64 people had been reported four times to the city council but it took eight weeks for an inspection to be carried out.
“In that particular case, we absolutely put our hands up,” he said. “That situation should have been referred to Dublin Fire Brigade much earlier. It didn’t happen.
“We’re very much reliant on the members of the public and tenants and everybody else to make contact with us,” he stated.
“We want to encourage people to make contact with us rather than making it awkward for people.”