The Gujarat government has initiated plans to allow buildings 100 metre high or more in five cities: Ahmedabad, Gandhinagar, Surat, Rajkot and Vadodara. This week, the Urban Development and Urban Housing Department issued a notification incorporating a new chapter in the Comprehensive General Development Control Regulations (CGDCR)-2017 and invited public suggestions and objections within 60 days.
What are the reasons behind the move?
“The government does not intend to change the entire skyline in these cities. The main intent is to attract some iconic buildings in these cities. We are not incentivising developers in any way. However, we are sure this move will help attract FDI in real-estate,” said Prakash Datta, Deputy Secretary and Officer on Special Duty in the department.
Jaxay Shah, chairman, Confederation of Real Estate Developers’ Associations of India, also believes this move “pending for the last eight years” will attract FDI.
Another reason cited by officials is that urban land is getting scarce and that “horizontal development of cities need more land, which is getting expensive by the day”.
What is the current height restriction?
The limit was 45 m during 2001 (Kutch earthquake) and then raised to 70 m (22-23 floors) in 2017. The new policy allows builders to go as high they wish, provided a road at least 30 m wide adjoins the plot and they have an airport no-objection certificate.
If a builder has a 2,500 sq.m. plot, the maximum height can be 150 m. If the plot is 3,500 sq. m, he or she can build to any height. Skyscrapers can come up in zones that have an FSI (Floor Space Index) more than 1.2. The changes permit a total FSI up to 5.4, but the additional FSI over 1.2 will be chargeable at 50% of the jantri value (ready reckoner rates) of the non-agricultural land.
Will the move bring down housing cost?
While the government has said tall buildings will help bring down the cost of housing, builders say construction will be costlier. “Skyscrapers are usually meant for luxurious residences and commercial structures. Even maintenance costs are high,” said Shah, who also heads Ahmedabad-based construction firm Savvy Infrastructure Pvt Ltd.
Ahmedabad-based structural engineer Vatsal Patel said the primary costs in constructing a tall building are foundation and labour. The higher the floors, the more the cost. For instance, as the structure rises, windows will need thicker and thicker glass. Again, labour costs increase after every fifth or sixth floor by 5-7%.
Market demand is crucial. “In most cities, where land rates are very high, skyscrapers are in demand. Other factors like scenic views and pollution play a role,” Patel said.
How are earthquake-related concerns being addressed?
Ahmedabad and Gandhinagar are not far from the Cambay fault, and buildings in seismically active Kutch are not allowed more than one floor. The CGDCR mandates that proposed tall buildings will have to follow the National Building Code which lays down design guidelines for construction in seismically active zones. A Special Technical Committee will be formed with experts in structural engineering and soil mechanics who will examine each project proposal.
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What does a builder need to do?
“Skyscrapers will require extraordinary due diligence as far as structural safety, fire services and third party assessments are concerned. So permissions will take longer than conventional projects or buildings,” said Shah. However, government officials said the number of permissions will remain the same.
What does it take to build a tall building?
The Bureau of Indian Standards has special clauses for tall structures, including details like wind load and earthquake resistance. Foundation and structural requirements too are crucial. Tall structures have to consider the horizontal load — how it will behave in an earthquake and the wind load — and the static load, which is the building’s own weight and occupancy load.
Foundation: Foundations can go between 30 ft and 300 ft deep depending on soil conditions. “A geotechnical consultant is always called in to advice the type of foundation that is relevant for the soil type. Once the structural engineer has the data on the load of the building, the consultant will suggest the foundation type,” Patel said.
Structure: Once wind tunnel tests are cleared, the structural framework is decided. To combat wind load, the building is made vertically strong through sheer walls. These reinforced cement concrete walls go all the way from the foundation up to ensure the building holds even at 250 metres. Many tall buildings in cities such as Hyderabad and Bengaluru now have steel rather than concrete in their superstructure, which makes construction quicker.