High property prices cause high rents, high rents in turn can result in more people sharing a rent so they can afford it. For some people the thought of paying £90 for a nice room in a nice house is unthinkable, as is the thought of paying £45 for a nasty room in a nasty house. The solution, of course, is not just to share, but to share with as many people as are needed to bring the rent down to an affordable price.

Across Dublin there are average-sized houses and apartments, which have a lot of people, mainly in their early twenties, traipsing in and out each day. Neighbours may worry that they are brothels or drug dispensing centres - in fact, it is more likely that a lot of people are simply living there in cramped conditions.

There are no official statistics of course of how many people are opting for cramped living conditions over an empty wallet, but there is some anecdotal evidence.

Mr Ciaran Murphy, director of Threshold says that although they have not come across a significant volume of overcrowding, a few specific cases have been brought to their attention.

Because Threshold wouldn't always be made aware of the fact, he says it is very hard to establish if it is a growing trend. But there is increasing evidence of people willing to share accommodation.

Sharing accommodation is one thing, sharing floorspace is another matter entirely, and having any more people living in the house than are on the lease is a breach of the lease. He says that if a lease has been signed "Only those who sign a lease have a right to live there." A breach of the lease means the landlord can ask them to leave.

"The issue of overcrowding," Mr Murphy says, "is a direct consequence of increases in rent." People overcrowd to bring their rent down. But, he said, there is also the issue of finding accommodation - there is a lot of competition.

The competition for accommodation means househunters will opt for what they believe to be the best of a bad lot; and if more bodies means keeping a roof over their heads, that is what they will do.

"It'd worry me that people have substandard accommodation," Mr Murphy says, "but overcrowding is just a symptom of a bigger problem."

Rents are on the increase - but houses are still the same size.