When engineer Paul Bates wanted to convert his garage into a spare room he realised that he'd need more space in his driveway to park his two cars. So he invented a contraption that would enable both cars fit into a driveway or space big enough for only one car.
This first design involved digging a 10-foot deep pit in the driveway, camouflaged with a choice of surfaces but used to house the two cars; one on top and one underground.
Alternatively, if you don't want to go to the trouble of digging up your driveway you can use the freestanding unit. It works like this: car one is driven into the street-level unit, which then lifts up the hydraulic stilts; car two then drives under the stilts. Because they are moveable units they do not require planning permission.
Four years on Bates has set up Intergarage 3000 which manufacture the doubling up units. "They have increased the value of houses fitted with them, in London property prices have gone up by 12 per cent," he said.
Tom McCormack, managing director of Double Parking Limited, the company which distributes the units in Ireland, said: "It took a while for the stackers to sell here but sales have taken off now. They are mainly bought by businesses and mostly in Dublin, although we are selling in Galway and Cork. They are also very popular with apartment owners."
Pa Nolan, Director of Fexco Stockbrokers in Dublin's Ely Place bought six units for the company's car park, he said: "We were faced with a typical Dublin 2 scenario where space is at a premium. We initially bought two as a test then purchased another four."
One of the difficulties with the units though is that the car on top can't move out without co-operation from the car driver below. "They are simple mechanically, the car on top can't move out unless the car below moves so you have to make sure the driver of the top car doesn't go missing," adds Mr Nolan.
If you're worried that the car above will come crashing down on your car, fear not, unless you drive a Rolls-Royce. The upper unit can take vehicles weighing up to 3,000 kilograms. McCormack says: "The only car that weighs over 3,000kg is a Rolls-Royce, so if you drive a Roller you wouldn't be able to use the stacker."