Types of Green Flat Roofs

Extensive Green Roofs

Extensive Green Roofing systems consist of lightweight, naturalistic planting that provides extensive plant cover with minimal maintenance and a wide range of benefits, including:

  • Little modification of the roof environment, ensuring suitability for new or refurbishment applications.
  • Naturalistic style planting systems, that require minimal care, irrigation and maintenance.
  • A thin layer of lightweight growing mediums, typically between 65mm and 150mm.
  • A wide range of grass, herbaceous, succulent and moss species, that establish self-sustaining plant communities.
  • Suitability for use on roof slopes (from 0 to 35° slope), with measures possibly needed above 5° Pitches greater than 35° may be accommodated subject to design.
Typically weighing 80 to 90 kg m². (saturated system weight) lighter variations can be specified, but the membrane will require independent attachment.

Intensive Green Roofs

Intensive Green Roofing Systems are planted areas generally consisting of perennials, shrubs, trees and/or turf, effectively creating a traditional English garden at roof level.

Generally laid out in sections to include usable areas of terraces and paths, alternating with intensively planted areas and planters, these systems require the consideration of many different criteria, including: 

  • Frost hardiness of plants
  • Resistance to damage by wind
  • Growth rate
  • Compatibility/competition with other plants
  • Resistance to extreme climatic conditions
  • Resistance to pests and diseases, which may be prevalent under these extreme conditions
Similarly, an Intensive system will require intensive care, irrigation and long term maintenance. This will include weeding and removal of unwanted vegetation, cutting and trimming of plants and preventative measures to protect plants against pests and diseases.

Biodiverse Green Roofs

A Biodiverse Green Roofing system is designed to enhance the specific requirements of local flora and fauna. As such, its construction above the Sarnafil membrane level is dependent on the client’s environmental objectives and any local planning constraints.

The benefits of a biodiverse green roof include:

  • Little modification of the roof environment, ensuring the suitability for new or refurbishment applications.
  • Natural self-sustaining plant communities that require minimal care, irrigation and maintenance.
  • A thin layer of lightweight growing mediums, typically between 65mm and 150mm.
  • Suitability for use on roof slopes (from 0 to 35° slope), with measures possibly needed above 5°, pitches greater than 35° may be accommodated subject to design.