Green Roofing with Superior Water Proofing for Sustainable Cities : Mehul Parikh

A candid exchange with Mehul Parikh, President- Customer Service Group, Construction Chemicals, Pidilite, on Integrating Nature and Technology, and how Waterproofing enables the Rise of Resilient, Eco- friendly and Sustainable Rooftops.

As cities continue to grow vertically, the concept of green roofs is taking root—literally and figuratively—across the world. Green roofs—also known as vegetative or living roofs—are roof surfaces that are partially or completely covered with vegetation, planted over a waterproofing membrane. Far from being just decorative, green roofs play a vital role in sustainable urban development.
With the 2024 update to the Energy Conservation and Sustainable Building Code (ECSBC) in India, green roofs are no longer just a sustainability buzzword but a strategic mandate for future-ready buildings. The new ECSBC code highlights the role of green roofs in reducing the Urban Heat Island (UHI) effect, improving thermal performance, and enhancing liveability in dense urban settings.
The new ECSBC is applicable to commercial and office buildings either single or for building complexes that have a connected load of 100 kW or greater or a contract demand of 120 kVA or greater and are intended to be used for commercial or office building. For reduction in urban heat island effect minimization the ECSBC clearly mandates that all roofs that are not covered by solar photovoltaics, or solar hot water, or any other renewable energy system, or utilities and services that render it unsuitable for the purpose, shall be either cool roofs or vegetated roofs. For qualifying as a vegetated roof, the roof areas shall be covered by living vegetation of >50 mm high.
One of the primary benefits of green roofs is their ability to mitigate the UHI effect. Conventional rooftops, made of concrete and asphalt, absorb and radiate heat, causing cities to become significantly warmer than surrounding rural areas. Green roofs, with their vegetation layers, act as natural insulators—absorbing less heat, reducing surface temperatures, and lowering ambient heat levels. This has a cascading impact on reducing energy consumption for cooling, thereby improving a building’s energy efficiency.
Some of the known and proven benefits of Green Roofs in Urban high population density areas are:

Evapotranspiration

• Vegetation on green roofs releases water vapor through transpiration and evaporation.
• This process cools the surrounding air, lowering ambient temperatures, especially during hot days.

Albedo Effect & Surface Temperature

• Conventional roofs (e.g., concrete, bitumen) absorb and retain heat due to low reflectivity.
• Green roofs have a higher albedo and lower thermal mass, meaning they absorb less heat and radiate less back into the environment.
• While green roofs may not have the highest albedo, they compensate by cooling through evapotranspiration, providing similar thermal comfort benefits.

Thermal Insulation

• The vegetation and growing medium provide insulation, reducing heat transfer to the building and limiting heat emissions from the roof to the outside air.
• Studies show that extensive green roofs can reduce roof surface temperatures from 60–80°C to 30–35°C on sunny summer days.
• Urban areas with high green roof coverage experience significantly lower localized air temperatures—often 1–3°C cooler than comparable areas without green roofs.

Heat Storage Reduction

• Traditional roofing materials store heat and release it at night, keeping cities warm after sunset.
• Green roofs reduce this nighttime heat release by limiting daytime heat absorption.

Enhancing Thermal Comfort

• Indoor Temperature Regulation.
• Green roofs can potentially reduce indoor temperatures by up to 2–5°C in summer.
• This leads to more stable indoor climates, especially in upper-floor rooms directly beneath the roof.

Reduction in HVAC Load

• Cooler indoor spaces reduce the need for air conditioning, cutting energy consumption and improving comfort.
• Outdoor Microclimate Improvement.

Noise and Air Quality Benefits
Vegetation also improves acoustic insulation and traps airborne pollutants, contributing to a more comfortable, and healthier indoor and rooftop environment.
Global best practices offer valuable lessons. Singapore’s government-led Green Roof policy mandates rooftop greenery for new buildings through its Landscaping for Urban Spaces and High-Rises (LUSH) initiative. It integrates greenery into urban planning to tackle climate challenges while making the city more liveable. Cities like Toronto and Copenhagen have also incorporated mandatory green roofing into building codes, encouraging biodiversity and better stormwater management. In Toronto, studies suggest that greening just 25% of city rooftops could reduce the UHI effect by 1 °C, while 50% coverage could achieve a 2 °C drop. Similarly, modelling in Seoul showed that greening 90% of rooftops could cool city air by up to 0.54 °C, reduce surface temperatures by 2.17 °C, and cut energy consumption by 7.7%.
From a human-centric perspective, green roofs improve the quality of life for occupants. Access to rooftop gardens has been linked to reduced stress levels, better mental well-being, and opportunities for urban farming and community interaction. For commercial spaces, green roofs create breakout zones, recreational spaces, and even co-working terraces—fostering healthier and happier environments.
However, the success of green roofs lies beneath the surface: in the robustness of their waterproofing systems. Unlike standard roofs, green roofs demand a robust, high-performance waterproofing layer that can withstand root penetration, resist constant moisture exposure and water immersion conditions, have high chemical resistance, and sustain temperature variations. A failure in waterproofing not only jeopardises the roof structure but also undermines the environmental benefits.
A comprehensive and effective Green Roof system necessarily includes multiple functional layers starting with a properly designed structural roof slab/side walls , a robust waterproofing that resists permanent water immersion conditions, soil filter and drainage systems , root barriers in large planter/tree pit zones, and irrigation, followed by the horticultural layers and plantation depending on their complexity.
At Pidilite, with a vast experience of several decades and several successful Green Roofs done in India , we recommend a multi-layered waterproofing approach including a root-resistant liquid spray applied waterproofing membrane, a geotextile protective layer followed by slope making screed with a soil filter cum drainage layer as a minimum . Incorporating a spray applied PUF thermal insulation sandwiched between the primary waterproofing layer and with a waterproof sealer coat on the top, below the screed further enhances the overall system with heat insulation benefits and makes it compliant to new ECSBC guidelines. This ensures long term durability and leak-proof performance across all weather cycles.
At Pidilite Industries we understand the challenges posed by the demanding conditions that a Green roof entails. With our extensive portfolio of high-performance waterproofing products under brands like Dr. Fixit, we offer tailored solutions for Green Roof systems—including root-barrier coatings, breathable membranes, and systems tested for durability and longevity.
Our Pidilite Professional Solutions team backed by our technical Product Specialist experts work closely with architects, structural engineers, developers and contractors, and project management consultants to recommend system-based waterproofing solutions that are compliant with relevant codes and best practices.
Few current promising Initiatives in India for Green Roofs

• Delhi Development Authority (DDA) has explored green roof pilots.
• IGBC & GRIHA Rating Systems award points for rooftop greening.

Private Sector Adoption: Some IT campuses, malls, and institutions have implemented extensive green roofs for energy savings and aesthetics.

Few Recommendations for India to consider for promoting Green Roofs are

• Policy Mandates: Consider introducing city-level requirements for large or government buildings.
• Incentives: FSI bonuses, stormwater credits, or property tax incentives to encourage adoption.
• Building Codes: Integrate green roof provisions in National Building Code (NBC) or state bye-laws and develop relevant IS standards for green roof construction.
• Demonstration Projects: Showcase pilot projects in smart cities or government constructed office buildings and mass housing projects to build confidence.

Public-Private Partnerships: Encourage corporate campuses and real estate developers to adopt green roofs via CSR or ESG incentives.
As GREEN buildings become the norm, green roofs are more than an aesthetic choice—they are a climate action tool, a wellness enabler, and a technical challenge worth mastering. With the right approach and solutions, India’s rooftops can transform from barren slabs into thriving ecosystems.