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The following is a short summary of the habitat type and how to create/enhance it to a "good" condition. For an informed position, please refer to official up-to-date Government guidance or the UK Government's Condition Assessment Sheet.
🔺 IMPORTANT
This habitat type should only be selected if the green roof meets the very specific criteria set out below. If it doesn't, or you are not sure, you should consider instead Urban - Other green roof.
Synonyms: Biodiversity Green Roof, Extensive Green Roof
Description: A Green Roof that has been designed to promote and boost biodiversity. It should have a depth of substrate (not including a blanket or turf) that varies between 80 and 150 mm, with at least 30% of the roof at 150 mm deep. It should be planted and seeded with a wide range of dry grassland wildflowers and Sedum species and have at least a 60:40 ratio of other wildflowers to Sedum. It should also have other habitat features like bricks for nesting bees and logs.
If you wish to select this habitat on a habitat selection screen, it can be found under Urban (see guide).
Note that this is defined as an ‘extensive’ Green Rood by The German Landscape Research, Development and Construction Society (FLL), and the Green Roof Organisation (GRO) Code of Practice 2021. It should feature many more wildflowers other than Sedum species, with the other species chosen to promote biodiversity. There should be over 25 different types of wildflower species.
Key Species
Sedum acre
Sedum anglicum
Sedum forsterianum
Sedum rosea
Sedum villosum
Note: It’s important that no more than 40% of the species are Sedum.
Assessment Questions
Are there at least 25 different wildlfower species?
Does it have a depth of substrate (not including a blanket or turf) that varies between 80 and 150 mm?
Has it been planted with a range of species, such that Sedum only accounts for less than 40% of the species.
Does it include features to promote biodiversity like logs or bee bricks?
If YES, then it is likely 'Urban - Biodiverse green roof'
How to Create / Enhance to a "Good" condition
How to create
This habitat requires certain criteria to be met:
No more than 40% of the species in the plant mix can be sedum
There must be at least 25 different wildflower species
The substrate depth must vary between 80mm and 150mm (with, ideally, 50% being 150mm)
Incorporate other features to promote biodiversity (such as logs, bee bricks or other habitats).
For more specific creation advice, please refer to the Green Infrastructure Standards. Pricing information can be found here.
How to get a "moderate" rating
At least two of the following will be met:
Vegetation structure will be varied, providing opportunities for vertebrates and invertebrates to live, eat and breed. A single structural habitat component or vegetation type will not account for more than 80% of the total habitat area.
The habitat parcel will contain different plant species that are beneficial for wildlife; for example, flowering species will provide nectar sources for a range of invertebrates at different times of year.
Invasive non-native plant species (as listed on Schedule 9 of WCA1) and others which are to the detriment of native wildlife cover less than 5% of the total vegetated area.
The roof has a varied depth of 80-100 mm, with at least 50% at 150mm, planted and seeded with wildflowers and sedums (or pre-prepared with such plants)
How to get a "good rating"
All of the following will be true
invertebrates to live, eat and breed. A single structural habitat component or vegetation type will not account for more than 80% of the total habitat area.
The habitat parcel will contain different plant species that are beneficial for wildlife; for example, flowering species will provide nectar sources for a range of invertebrates at different times of year.
Invasive non-native plant species (as listed on Schedule 9 of WCA1) and others which are to the detriment of native wildlife cover less than 5% of the total vegetated area.
The roof has a varied depth of 80-100 mm, with at least 50% at 150mm, planted and seeded with wildflowers and sedums (or pre-prepared with such plants)
There will be additional habitats, such as sand piles, stones or logs.
How to Create / Enhance to a "Good" condition
Guide 1 - Green Infrastructure Planning and Design Guide
Guide 2 - Green Infrastructure Standards
Guide 3 - Creating Green Roofs for Invertebrates
Please note that this is a simple guide to help identify the habitat. For a definitive description, please refer to UKHab documentation. Joe's Blooms takes no responsibility for the content of external links.