Profitable apartments in Dublin city centre require a joint income of €87,000.
This makes affordable flats next to impossible to build, according to a report from the Society of Chartered Surveyors.
The research also shows that it's cheaper to build a three-bed semi-detached house in Dublin, than a two-bed apartment.
One of the authors of the report, Paul Mitchell, says it is no surprise.
"Apartments are always more expensive than housing," said Mr Mitchell.
"It's come as a little bit of surprise to us that it's a surprise to the general public.
"Apartments are more complex, they are a bigger structure, they are a different product altogether than a domestic house built with blocks and timber."