Types of green roofs: extensive, semi-intensive and intensive
When we talk about sustainability within construction or sustainable buildings, green roofs – considered the “fingerprints” of growing and evolving cities – play an important role.
Contributing to the development of more sustainable and climate change resilient cities, green roofs fall into three main categories: extensive, semi-intensive and intensive.
Read on to find out the differences between these three categories and their advantages.
The importance of green roofs
Green roofs, increasingly essential in the construction industry, consist of a layer of vegetation planted on top of a waterproofing system that is, in turn, installed on top of a flat or slightly sloped roof.
Green roofs contribute to the identity of a given location as they bring life to individual buildings and entire urban areas, supporting sustainable construction.
Their oxygen-regenerating capacity, heat island effect mitigation and contribution to thermal coating make green roofs a priority for architects and planners when designing a building.
Reasons why you should invest in green roofs
In addition to their visually pleasing and appealing impact, green roofs offer unparalleled ecological and economic benefits.
Thus, we can list some ecological advantages:
- Increased water retention;
- Improvement of the urban microclimate;
- Retention of toxic dust particles;
- Improved acoustic insulation;
- Increased life expectancy.
Similarly, we can list economic benefits of green roofs:
- Greater water savings and reduction of rainwater waste;
- Reduction of building maintenance costs;
- Reduction of energy costs;
- Increase of useful space.
Now that we know more about some of the main advantages of green roofing, let’s learn more about its characteristics.
Extensive, semi-intensive and intensive roofing: What distinguishes them?
The first rooftop gardens appeared in the ancient civilizations of the Tigris and Euphrates River, such as the hanging gardens of Babylon in the 7th and 8th century before Christ. Romans also applied this system to some of their buildings.
The emergence of new construction techniques that generalized the use of flat roofs with the capacity to support greater loads allowed the expansion of garden roofs.
In general, three categories of green roofs are recognized.
Extensive Green Roofs
Extensive green roofs present themselves as an ecological alternative to conventional surface protection, such as gravel, slurry or screed. Besides being lighter, they have a reduced construction height, with a maximum substrate thickness of 15 cm and the weight of the substrate/vegetation set is usually less than 120kg/m2.
This cover is considered the simplest. It predominates plants that grow as naturally as possible and need little water, such as succulents and herbaceous perennials, and frequent watering and pruning can be dispensed with. So, the need for maintenance is also reduced.
Semi-Intensive Green Roofs
A semi-intensive green roof consists mainly of herbaceous plants, small shrubs and aromatic plants. Unlike extensive green roofs, in which the vegetation follows its natural growth process, this type of green roof allows the landscape architect and the client to choose the planting according to their needs and wishes.
The thickness of the substrate varies between 15 and 30 cm, and the drainage elements should have a greater capacity to retain water. As far as maintenance is concerned, this is moderate and should ensure a correct evolution of the vegetation, as well as an efficient performance of the drainage and irrigation systems.
Intensive Green Roofs
Intensive green roofs are the most comparable to a conventional garden. Accessible and with multiple functions, these roofs need a deeper system configuration, with greater water retention capacity.
In addition, since it can include shrubs, trees, ponds and a wide variety of ecosystems, maintenance must be regular.
In short, extensive green covers are the most common, featuring a shallower substrate layer. Consequently, they represent a lower load for the building.
We can also conclude that a healthy growth and development of vegetation in green roofs is related to the proper selection of different plant species, as well as the irrigation and monitoring needs of the vegetation.
High performance roofs with guaranteed longevity
Are you looking for professional advice for your project, but don’t know where to start? Prudêncio helps you throughout the entire process – from the waterproofing system, insulation and drainage to the design and implementation of the garden or green space –, focusing on environmentally friendly materials and processes.
This way, and whenever possible, we advise our customers to adopt green roofs in the renovation of the building or to integrate them in new projects.
Contact us to find out more about our solutions!