Green roofs, also known as living roofs or rooftop gardens, are roofing systems designed to support vegetation and enhance urban environments. By combining waterproofing, drainage and planted layers, green roofs help improve building insulation, reduce stormwater runoff, enhance biodiversity and combat the urban heat island effect. Suitable for residential, commercial and public buildings, green roof systems create greener, more energy-efficient spaces while helping protect roofing membranes and improve long-term building performance. Green roofs offer an effective solution for creating environmentally responsible and visually appealing buildings.
Benefits of Green Roofs
- Helps protect and extend the lifespan of roofing waterproofing membranes by shielding them from UV exposure and freeze-thaw cycles
- Improves thermal insulation and energy efficiency, helping reduce building cooling costs during warmer months
- Reduces the urban heat island effect by increasing green space in built-up areas
- Retains up to 75% of rainwater, helping slow stormwater runoff and reduce pressure on drainage systems
- Improves air quality through natural CO₂ absorption and air filtration from vegetation
- Reduces energy consumption by protecting buildings from heat gain in hot weather and retaining warmth during colder months
- Creates attractive rooftop green spaces with a natural, park-like appearance
- Enhances biodiversity by creating habitats for plants, insects and wildlife
- Can contribute towards sustainable building certifications and environmental targets
- Supports more sustainable urban development with environmental, social and aesthetic benefits
Types of Green Roof Systems
There are four main types of green roofs: extensive (sedum), intensive (brown), biodiverse and biosolar green roofs. Each type offers different benefits and can be designed to meet the specific requirements of a project, from low-maintenance planting and enhanced biodiversity to combining green roof systems with renewable energy generation. The most suitable system will depend on factors such as the building, roof design, intended use and desired environmental benefits.
Extensive green roofs, often called sedum roofs, are lightweight and require less plant maintenance. With only a few centimetres of soil, extensive green roofs typically support plants that drought-tolerant such as grasses and windflowers since they are shallow-rooted and use little water. Extensive roofs are often used in areas that will not be subject to regular traffic.
Intensive green roofs are heavier, and hense require far more maintenance. They are designed to include a deeper soil that can accommodate trees, shrubs, bushes and vegetable gardens.
Biodiverse green roofs are designed to create a natural habitat that replicates the ecological environment of the site and thus supports local plants, birds, insects and other wildlife. Biodiverse roofs can require a deeper or more varied growing medium and therefore have structural requirements similar to those of intensive green roofs.
Biosolar green roofs combine green roof planting with solar photovoltaic (PV) systems to make efficient use of available roof space. Biosolar roofs can be designed to suit both extensive, intensive and biodiverse green roof systems, depending on the requirements of the project.
Sika Green Roof System Build-Up
- Sika drainage composite board
- Sika waterproofing membranes (single ply membranes e.g. Sarnafil®/Sikaplan®, liquid applied membranes e.g. Sikalastic®, bitumen membranes e.g. SikaShield®)
- Sika protection or separation layer (e.g. S-Felt)
- Sika thermal insulation (e.g. Sikatherm®)
- Sika vapor control layer (e.g. Sarnavap®)
- Sika roof accessories (e.g. Sarnafil® walkway pads, prefabricated accessories, etc.)
- Sika scuppers, drains and more, depending on project requirements
Please note: refer to Sika specification for product names as they may vary depending on the build-up
Sika Waterproofing Membranes for Green Roofs
Single Ply Membranes
Sarnafil® and Sikaplan® single ply membranes provide durable, root-resistant protection for green roofs with over 30 years of proven performance. They can be installed in most weather conditions, including low temperatures, offering greater flexibility on site. Soil with a minimum weight of 80 kg/m2 provides the necessary wind uplift resistance, eliminating the need for any additional mechanical fastening.
Liquid Applied Membranes
Sikalastic® liquid applied membranes provide fully bonded waterproofing that eliminates the risk of lateral water underflow, making any potential leaks from future damage easy to identify and repair. They offer excellent resistance to roots and micro-organisms, fast application and curing, and can be applied directly onto prepared concrete decks, making them ideal for inverted green roof systems.
Bitumen Membranes
SikaShield® P55 PE RT 4 mm bitumen membrane provides durable waterproofing for green roofs. Designed with anti-root additives, it helps protect roof gardens and planted areas from root penetration, while also resisting humid acids and fertilisers for long-term performance in direct contact with soil.
How Do Green Roofs Work?
Green roofs work by combining layers of waterproofing, drainage, growing medium and vegetation to create a planted roofing system. The waterproofing layer protects the building, while drainage layers manage excess rainwater and the growing medium supports plant growth. Together, these layers help absorb rainfall, improve insulation, reduce heat build-up and enhance biodiversity, making green roofs both environmentally and structurally beneficial.
Which Type of Green Roof is Right for Your Project?
There are several types of green roofs, each designed for different building requirements and uses. Extensive green roofs are lightweight, low maintenance systems that typically use sedum or low-growing plants, while intensive green roofs support larger plants, gardens and recreational spaces but require deeper soil and more maintenance. Biodiverse and brown roofs are designed to encourage wildlife and recreate natural habitats.
FAQ
Green roofs offer a wide range of benefits, including enhanced thermal insulation, reduced rainwater runoff, improved air quality, extended roof membrane lifespan and increased biodiversity in urban areas.
Sika provides solutions for four types of green roofs: extensive (sedum), intensive (brown), biodiverse and biosolar green roofs. Extensive systems are lightweight and low maintenance, while intensive systems have deeper growing mediums that can support a wider variety of plants and landscape features. Biodiverse green roofs are designed to create habitats that support a variety of local plants and wildlife, while biosolar green roofs combine green roof vegetation with solar PV systems to maximise the use of available roof space.
Yes, Sika’s roofing membranes, including Sarnafil® and Sikaplan®, are resistant to root penetration and specifically engineered for green roof applications, ensuring long-term waterproofing and protection.
Yes, green roofs can be retrofitted onto existing structures, provided the roof can support the additional load. A structural assessment should be carried out before installation.
Maintenance depends on the type of green roof. Extensive roofs require minimal upkeep, while intensive systems need regular care similar to a traditional garden.
