Invading another person's space could cost you your wheels - at least until you pay to get the clamps removed. With city centre car-parking spaces selling for between £20,000 and £50,000, and suburban ones fetching £10,000 to £20,000, many management companies are resorting to drastic measures to halt unauthorised parking in apartment block car-parks.

While the parking problem is more acute in the city centre, it can affect suburban apartment schemes close to office blocks, shopping areas or scenic spots. Some may have to deal with sporadic invasions if they are near exhibition or music venues such as the RDS and the Point, or sports arenas such as Croke Park and Lansdowne Road.

But it's not always strangers who are the culprits - spaces can also be nabbed by other residents or their visitors. With parking spaces at a premium, often little or no extra provision is made for visitors, particularly in city centre developments.

Some apartment blocks, particularly those built in the suburbs in the 1970s and 1980s, are finding that communal parking systems are now feeling the strain. "I've heard of people resorting to fisticuffs over parking," says Tony Macken, of Foremost Property Management.

"Take, for example, a block where there may have been 60 apartments built and 60 non-designated parking spaces provided. There weren't as many cars around when some of these schemes were built and this system would have operated in a very civilised manner for years. But with the increased pressure on parking, outsiders coming in and taking spaces, residents encouraging their friends to park there and the fact that many apartments are now two-car homes has led to bad feeling."

"It can be annoying if your space is taken," says David Lewis of Sherry FitzGerald. "Not to mention if you find yourself blocked in by another car. You can't ring 50 to 100 doorbells to see whose car it is. Some developments put a big sticker on car windows if they park in someone's spot, which is horrible because it's hard to get it off. A clamping company is paid a retainer, which can be expensive and people can get emotional and upset if they are clamped. I would be on for clamping people who park on grass verges but if it's someone else's space, it's not the end of the world and it can cause a lot of resentment."

The type of parking system employed depends largely on the likelihood of invasion.

Usually clamping is brought in as a last, desperate measure. Some management companies retain a clamping company to respond if a resident telephones about unauthorised parking. Others employ a clamper to patrol the car-park.

The problem with clamping, says Tony Macken, is that some residents can be over-vigilant. "Often the sign informing people that clamping is in operation is enough of a deterrent, but when people who live in the block and their visitors start getting clamped, this can lead to dissension."

"It's a delicate area," says Ben Gough of Wyse Property Management. "But it is coming in more. We do it in a minority of the developments we manage, with the full co-operation of the management company. Guidelines have to be clearly set out to meet legal obligations. The proper signage has to be put up and residents have to be informed that clamping is in force."

Some developments opt for electronic key and remote control parking systems.

"I'm not that much in favour of clamping," says Maria Mason of Petra Management. "It makes people very irate. Quite a few of the schemes we manage in the city centre have car-parks with remote control security gates. We issue one remote control per space, which is numbered. They are a sophisticated type of remote control that cannot be copied and the supplier we use will not issue new ones without our authorisation.

"Many residents plead with us for another remote control but we don't oblige because that's when problems start and people take advantage. You get all kinds of stories like the dog ate it or it fell in the bath but we usually say if they want another one they'll have to pay for it and their old one will be obsolete. We usually recommend the key in/key out remote control system which is more sophisticated and doesn't cost that much more than the standard remote control system.

"It would be easier to bring in clamping because the system we use requires a lot of diligence because you have to rigidly adhere to the rules or it doesn't work. I would hate to be responsible for grounding someone by having them clamped, particularly in a private development where someone might need to go to the airport or the hospital."

Security cameras, security huts, swipe cards, registration monitoring and barrier systems are other deterrents. Some developments, such as Custom House Square, have a security hut with cameras keeping an eye on the car-park.

While some spaces are designated - in other words, numbered according to apartment owner - others are unnumbered and communal and can be harder to regulate.

A car-park with a difference is the one attached to Alexander Court, on Fenian Street, Dublin 2, which brings the resident on a lift to the parking bay on the first floor - in their car.

According to a resident of Alexander Court, the lift system doesn't cause the delays you might expect. "The residents are in and out at different times, although occasionally there might be two or three cars at a time waiting to go on the lift. You drive on and turn the engine off. It is a bit odd at first but you get used to it very quickly."

Aidan Gavin of DTZ Sherry FitzGerald says there is a trend towards underground car-parking. "It's space the developers cannot build apartments on because there is no light so it means they are not wasting valuable space." Not everyone who buys a space uses it themselves. Renting spaces can be a big money spinner, with city centre rents ranging from £60 to £300 a month, the average being about £100 to £150.