Green Roof
/green roof/
Also known as: living roof, sedum roof, vegetated roof, planted roof, biodiverse roof
Definition
A roof system that incorporates a growing medium and vegetation layer above a waterproof membrane. Green roofs reduce surface water runoff, improve insulation, extend membrane life, support biodiversity, and can help meet planning requirements for biodiversity net gain.
In Practice
Green roofs are classed as extensive (shallow substrate 60-150mm, low-maintenance sedum or wildflower planting) or intensive (deep substrate 150mm+, capable of supporting shrubs or trees). Extensive green roofs are most common on flat and low-pitch roofs. The roof structure must be designed to carry the additional dead load - typically 80-150 kg/m2 for extensive systems when saturated. Planning authorities increasingly require green roofs on flat-roofed extensions and new buildings.
UK Building Regulations
Approved Document H - Drainage and Waste Disposal
Green roofs can contribute to SuDS requirements under Approved Document H. Biodiversity net gain requirements in planning may specify green roof provision on new developments.