Intensive green roofs maximize the value from a building's footprint, offering space for recreation and relaxation; much like a garden or park. Ranging from outdoor roof space to ground-level landscapes above subterranean car parks, intensive roofs often comprise a mix of hard and soft landscaping.
Intensive green roofs typically require regular maintenance, but provide significant benefit to the building's performance (e.g. stormwater, thermal, acoustic etc) in addition to the amenity features.
Specifying an Intensive roof
The design of an intensive roof is highly dependent upon the intended use of the roof area. Intensive green roofs include, at one end of the scale, roof gardens that combine pedestrian walkways with lawns and/or plants; to vehicular-trafficked landscapes at the other extreme.
The configuration of the roof must encompass a drainage layer, substrate and irrigation system that is appropriate for the application, accounting for structural and horticultural requirements.
Blackdown Roof Garden planting schemes can include a near-limitless diversity of plant types, with trees, shrubs, and herbaceous perennials; often combined with areas of lawn, paving and even water features:
Diverse mixes of plants and shrubs create a varied appearance, with different shapes, colours, heights, flowering times etc maximising all-year round aesthetics. However, it is imperative that the mix of plants is carefully considered to ensure that co-habitable species are selected.
More demanding plants, including trees, can be accommodated by increasing the depth of substrate included in the roof to ensure that the plants' needs are fully met.
Kerb upstands can create aesthetically-pleasing methods of retaining deeper substrates in localised areas of the roof through the use of recycled timber etc.
Containerised and root balled plants with different requirements can be included in the same roof area as bedded plants. By locally varying the type and depth of substrate, a more diverse range of plants can be included in the design.
Offers the opportunity to accommodate diverse ranges of plants within the design.
Lawned areas can be designed into roof applications.
Requiring a substrate that is enriched with a greater amount of organic matter (relative to other roof types), lawns typically also require some form of irrigation to prevent the vegetation from dying during prolonged, dry summer periods.
A variety of hard landscaping options - from pedestrian to vehicular traffic loadings - can be designed into an intensive green roof:
Stepping stones can be used to provide pedestrian access, whilst allowing the area to be permeable to the passage of storm water.
Where the roof structure allows, hard landscapes can be designed to withstand the higher design loads associated with vehicular traffic.
The dynamic and static loads imposed by such traffic should be reflected in the choice of waterproofing, drainage layer, substrate and surface.
Attractive paving stones can be laid onto a substrate or supported by non-penetrative stools to provide pedestrian access around the roof.
The use of a drainage layer, capable of storing this excess stormwater, below this type of landscape can be useful in the provision of water to the irrigation system.
Substrates & Drainage Layers
Intensive, planted roofs will need to include substrates with increased organic matter and nutrients and drainage layers with storage capacity to ensure that the required amount of water and air are supplied to the more demanding plants.
Pedestrian walkways can often be designed to be installed over the same drainage layer, providing cost-efficient installations that provide effective stormwater management.
Vehicular traffic will typically require the use of a reinforced concrete substrate, however with the appropriate specification, a single drainage layer can often be used beneath both planted and landscaped areas, providing stormwater management benefits.
Issues as diverse as lighting and equipment layout are important considerations when designing a roof for amenity benefits. Lighting should be designed to be appropriate to the application, whilst preventing glow or glare in accordance with BS5489-1:2003. Static equipment, such as benches or plant pot, should be positioned to allow safe circulation on the roof space.
Intensively Designed by Blackdown
Our Design Support Team will be happy to work with you to help deliver complex solutions that fulfill your project's requirements. For further information as to how we can help, please contact us.