© Justin Bere (Licensed under CC BY-SA 4.0). Note that this is a high-maintenance green roof, designed as a garden.
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.
Synonyms: Roof Garden, Roof Park
A high-maintenance green roof that is designed as a park or garden and includes shrubs, trees, perennials and grasses. Can include water features.
These are usually formal landscapes and are usually irrigated. They require frequent maintenance. Soils on roofs (known as substrates) are normally artificial, lightweight blends of material. Intensive green roof substrates are relatively deep (typically greater than 200mm). With intensive green roofs, the primary consideration in the conventional approach is amenity, which means that the planted area may not be as biodiverse as it could be. More attention can be made towards adopting a wildlife gardening approach, with native species and non-native species with a documented value for wildlife. Also, the balance between areas of paving and planting, with paving often the dominant surface, can result in the loss of ecosystem services and a reduction in the Urban Greening Factor. Where feasible, increasing substrate depth is good for absorbing rainfall and providing evaporative cooling.
⚠️ Important Note
To be classed as an "intensive green roof" the habitat must meet all three of the following criteria:
- ≥50% native and ≥30% non-native species of pollinator interest (≥80% overall)
- ≥70% of the surface is soil and vegetation (including water features); and
- ≤30% is hard standing (such as paving or firebreaks).
Assessment Questions:
- Is the feature a high-maintenance green roof designed as a park or garden?
- Are over half the plants native, and over a third species of pollinator interest?
- Is at least 70% of the habitat soil / vegetation / water features?
If YES, then it is likely 'Urban - Intensive green roof'
How to Create / Enhance to a "Good" condition
For creation advice, please refer to the Green Infrastructure Standards. Pricing information can be found here.
How to get a "moderate" rating
In a management plan aiming to achieve ‘moderate’ condition the plan will show the following:
A variety of flower species will be planted, with a focus on attracting insects like bees and butterflies along with other wildlife. Plants will be selected based on how appropriate they are to the size and design of the green roof. The species mix will ensure that there are flowers at all different times of year, providing nectar through the seasons.
The seed mix will be mostly native species. Where non-native plant species are present, they will not be harmful to wildlife. The planting mix will exclude invasive non-native species (INNS).
How to get a "good rating"
In addition to the characteristics for moderate condition, to get a ‘good’ condition the plan will show the following:
Management will seek to ensure a varied vegetation structure, with at least two physically different habitat elements or vegetation types or heights. The variety will mean that no single vegetation type covers more than 80% of the habitat area.
The management regime will ensure that bare ground will not be the most common habitat type.
Soil and vegetation will cover at least 70% of the roof area, rather than hard standing or built garden features.
Useful Resources
Guide 2 - Green Infrastructure Standards
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.