Green Roofing
A green roof, also known as a living roof system, is a layered assembly that includes vegetation installed over a waterproofing membrane. These systems are designed to support plant growth while protecting the underlying roof structure. Green roofs may contribute to planning and environmental objectives when specified in accordance with local authority guidance and relevant standards.
Sika® NatureRoof Green Roof systems
Sika® NatureRoof Green Roof Systems form one pillar of the Sika® Sustainable Roofing System package which has been developed to support the delivery of Government led climate change mitigation initiatives aimed at:
- Enhancing nationwide biodiversity
- Reducing flood risk through better rainfall management
- Enhancing energy security through renewable energy production
- Reducing carbon emissions on the journey to Net Zero
To a greater or lesser extent Green Roofs can contribute to each of these key Government activities.
Sika Project Examples
Sika® NatureRoof Green Roof Systems can replace, recreate or enhance flora and fauna biodiversity and they can absorb and/or attenuate rainfall, including summer storm events. Renewable energy can be generated through the incorporation of Solar PV, with improved energy performance versus a traditional roof. Building operation carbon emissions can be reduced through the cooling and insulating contribution of the green roof; and in Cities, the Urban Heat Island affect can be reduced as recognised by the House of Commons Environmental Audit Committee, Heat resilience and sustainable cooling Fifth Report of Session 2023-24.
All Sika® NatureRoof Green Roof Systems comply with the Building Regulations fire performance requirements and the GRO Green Roof Code of Best Practice.
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Green Roof Solutions
Green Roof Environmental Benefits
Green Roofs provide many sustainable and environmental benefits, and it is important to consider the requirements that need to be met when designing and specifying a project. Considerations will include any planning condition restrictions, limited discharge consents, biodiversity requirements, PV power outputs, load limits and many other factors. Your Sika Regional Sustainability Lead and Area Technical Manager are on hand to help you consider how you achieve these demands whilst ensuring the priorities of keeping the building dry and thermally insulated are met.
Biodiversity Enhancement
Biodiversity Net Gain (BNG) became law in February 2024, applying to most new major developments immediately and to small sites from April 2024.
Green Roofs can contribute to BNG and the Urban Greening Factor (UGF).
Rainwater Management
Green Roofs attenuate rainwater up to the point of saturation and evapotranspiration the moisture back into the atmosphere.
Creating a Blue Roof beneath the Green Roof can further enhance the Sustainable Urban Drainage (SuDS) contribution, elongating the drainage curve and helping reduce flood risk.
Renewable Energy
Solar Photovoltaic (PV) panels can be added to the Green Roof (and Blue Roof) construction to generate renewable energy.
The combination of the PV and the Green Roof produces an enhanced power output thanks to the cooling effect of the natural evapo-transpiration of the Green Roof.
Amenity and Aesthetics
Whether part of a Biophilic Design for enhanced health and wellbeing, an amenity function as a podium or terrace, or purely for the eye to behold, a Green Roof brings green space to the roof space.
Policy/Planning Consent
Whilst Green Roofs are a requirement within the London Plan and many other City Planning documents, the introduction of a Green Roof to a building is generally looked on as a positive contribution to the local environment by planning authorities.
BREEAM & LEED
Green Roofs can directly assist in obtaining credits within BREEAM and LEEDS assessment, including in flood risk, mitigating ecological impact, enhancing site ecology and long-term impact on biodiversity amongst other assessments.
Energy Savings
Plants absorb solar energy, as does the thermal mass of the growing medium, reducing the heat gain of the building. The growing medium also contributes to the thermal insulation of the building (to varying degrees), contributing to keeping heat within the building. These two factors contribute to reduced heating and cooling costs.
Improved Whole Life Costs
Ultraviolet radiation and thermal shock (the daily heating and cooling process) are the main causes of waterproofing material failure. The addition of a Green Roof shields the waterproofing membrane from these impacts, increasing the life expectancy of the roof system significantly.
Urban Cooling
Green roofs help reduce the Urban Heat Island effect by shielding waterproofing from solar heat and cooling through soil mass, plant absorption, and evapotranspiration. This impact is acknowledged by the House of Commons Environmental Audit Committee.
Water Quality
The vegetation naturally filters out
airborne particulates as the air passes. The particles are washed out into the growing substrate via natural rainfall or irrigation.
Air Quality
Plants naturally absorb oxygen during the day, cleaning the air as they do so. The function of the air travelling across a Green Roof can also filter out particulates into the growing medium.
Quieter Buildings
Green Roofs absorb sound through the thermal mass of the growing medium and vegetation layers.
Health
COVID-19 revealed mental and physical health risks in dense cities. Access to nature helps reduce these issues. Green roofs add urban green space, supporting wellbeing for building occupants.
Environmental Masking
Supports the integration of the building into the landscape and reducing its aesthetic impact within the environment. Habitat can be created to support local biodiversity including flora and fauna.
Food Production
Green roofs can provide new opportunities for urban agriculture, supporting locally grown food schemes and reducing food miles.