Bengaluru floods: Karnataka may ban basement parking in flood-prone areas; Experts flag higher costs, design challenges

Hindustan Times

23-05-2025

Karnataka is considering a ban on basement parking in flood-prone zones of Bengaluru to improve resilience against urban flooding. While real estate experts agree the move could help mitigate waterlogging risks, they caution it may lead to higher construction costs and design limitations for developers.
'While the idea of banning basements is sound from a flood-resilience standpoint, it's unclear whether it will be viable in the long run,' said an urban expert.
Basements typically cost twice as much to construct as ground floors. However, replacing basement parking with additional floors above ground may drive up costs even further, due to the need for extended plumbing, elevator systems, and electrical infrastructure. Additionally, such changes could reduce the efficient use of Floor Space Index (FSI), affecting project feasibility, they say.
After the recent flooding in Bengaluru, which claimed the lives of two men while they were pumping water out of a basement in BTM Layout, Karnataka deputy chief minister D.K. Shivakumar announced that the state government is considering a ban on basement parking in low-lying and flood-prone areas.
"I am taking a policy decision that wherever there is a low-lying area, we will not allow underground parking facilities in future. We will allow them to build parking spaces at a higher level," he told reporters while on his visit to assess the flood situation across the city.
"There is an idea to plan a way to park vehicles on the ground floor, instead of underground. Let people build houses on top of that," he said.
This comes amid relentless rainfall that has crippled Bengaluru in recent days, with heavy downpours triggering widespread waterlogging and flooding across the city. From upscale residential areas to major tech corridors, the rains have laid bare the city's fragile infrastructure and poor drainage systems, sparking serious concerns over urban planning and real estate development in flood-prone zones.
Also Read: Bengaluru floods: Was the city's Maharaja-era drainage system more effective and in sync with nature?
Experts say that eliminating basements may not significantly reduce construction depth. In many cases, foundations still need to be dug to around 6 metres, depending on soil conditions and structural requirements, potentially increasing overall construction costs.
'When a basement is part of the plan, excavation is already accounted for, and since the space is used for parking, there's no need for soil refilling—this offsets some of the construction cost,' said Abhay Gupta, structural consultant. 'Without a basement, however, the excavated area must be refilled entirely, which adds to expenses,' he explained.
Experts also noted that basements often cover more area than the actual building footprint, as Bengaluru permits construction up to 2 metres from the boundary wall.
"In contrast, ground-level or stilt parking is limited to the building footprint, which restricts capacity. In many cases, a single basement with that extra width can offer the equivalent parking capacity of 2.5 to 3 floor levels," Sarang Kulkarni, managing director, Descon Ventures, said.
While basements are typically more expensive to construct, often costing twice as much as a ground floor, adding extra floors to compensate for lost parking can further drive up construction costs due to additional plumbing, elevator, and electrical requirements.
'From a cost standpoint, avoiding basement excavation may seem beneficial,' said Sarang Kulkarni. 'However, this is offset by the reduced ability to fully utilize the Floor Space Index (FSI), which directly affects land value.'
FSI, or Floor Space Index, is a key urban planning metric that defines the maximum permissible built-up area on a given plot, effectively determining how many floors can be constructed.
Banning basement parking in commercial or retail developments could create significant challenges, experts say.
'Ground-floor space is prime real estate for retail. Without basement parking, that space must be repurposed for vehicles, leaving developers with two choices: build a multi-level car park with retail on the ground floor or position retail between parking levels and office floors above,' said Sarang Kulkarni, Managing Director of Descon Ventures. 'Both options increase the building's overall height.'
However, height restrictions—especially in areas near airspace and defence zones like Koramangala, Indiranagar, and North Bengaluru—limit vertical expansion. 'If developers can't utilise the full permissible Floor Space Index (FSI) due to these restrictions, it leads to suboptimal land use. While the basement ban may boost flood resilience, its long-term viability remains uncertain,' Kulkarni said.
In contrast, cities like Hyderabad, where FSI limits are more relaxed, allow greater design flexibility. Developers there often allocate the ground and first floors for retail, the second for parking, and the upper floors for office use, creating more efficient mixed-use developments.
Also Read: 'Does the area flood?' Bengaluru homebuyers and investors now have fresh real estate worry
Experts believe aesthetic concerns about visible parking on lower levels can be addressed, especially in residential projects, by drawing inspiration from global cities. In places like New York, buildings often feature grand ground-floor lobbies and use façade elements such as vertical gardens to screen parking areas.
However, construction methods significantly impact feasibility.
'In high-rise residential projects, the Mivan formwork system—known for its speed, monolithic concrete walls, and reduced labour—is commonly used above ground,' said Sarang Kulkarni. 'Basements, however, typically require traditional beam-and-column structures to facilitate vehicle movement, which Mivan isn't suited for due to its continuous wall design.'
If parking shifts above ground, developers must blend traditional construction with Mivan formwork, potentially increasing timelines and costs.
Another key concern is building height. 'If a project has a 60-metre height cap and 15 metres are used for above-ground parking, only 45 metres remain for residential units. This could reduce the number of floors, affect developer revenues and pushing up apartment prices,' Kulkarni noted.
While multi-level parking structures are a possible workaround, they often sacrifice green or open spaces.
Experts also warn that property values in low-lying or flood-prone areas could decline, as developers may avoid these zones due to the added challenges of parking and drainage constraints.
Experts suggest podium-level construction as a potential solution. Developers can build a raised concrete podium with a sealed, box-like structure beneath it for parking. Ramps can connect this podium to the basement, preventing groundwater seepage while preserving the advantages of underground parking.
'In cities like Mumbai, developers are sometimes granted additional height allowances when basements are used for parking,' said Gupta. 'On larger plots, basement areas can extend beyond the building's footprint, offering more flexibility and capacity—something that's difficult to achieve with stilt or above-ground parking due to zoning restrictions.'