Hey Pavan, the main reason for this shortage in North Chennai is because of small piece land. Most of the developers require for building apartment projects, since small land pieces belong to individuals, they prefer developing those into individual houses with single floor units.
@Jackie: the average price of land in the North ranges from Rs 4,000-4,500 per sq ft. The residential development in Chennai has been concentrated more in the South due to the presence of IT Industry. The localities which record highest demand for multi-storey apartments include Anna Nagar, Poonamallee, Kolathur, Ambattur and Perambur.