Homeowners in parts of the Dublin commuter belt are now at risk of negative equity, according to the authors of a new report.
Houses on the periphery of the greater Dublin area or away from public transport routes are said to be in danger of losing value.
The study, commissioned by the Society of Chartered Surveyors, found that Dublin's functional area now extends 100km into neighbouring counties.
It says there is now a demand from people who bought homes outside Dublin to move back towards the centre.
It shows that areas like Dundrum which are closer to the city centre and on a public transport route are seeing significant population increases.
But Templeogue, Ballinteer, Tallaght and Blanchardstown are seeing decreases in population.
Conor Hogan of the Society of Chartered Surveyors said there is an element of selection in the Dublin housing market.
He said those at greatest risk of negative equity would be those taking out a 100% mortgage on houses requiring a two-and-a-half hour drive from Dublin.
Dr Brendan William of UCD, who carried out the study, said Dublin needs suburban renewal with public transport projects completed as quickly as possible.
