Green roof types

Green roofs or, as commonly referred to as living roofs, are intentionally vegetated roofs.  Living roofs includes ornamental roof gardens, naturally vegetated roofs and also biodiversity roofs.  The types of roofs range from the commonly seen extensively vegetated to intensively vegetated roofs.

Within New Zealand, Maori used sod to build whare paruparu (dirt houses) and European settlers commonly constructed sod dwellings.


Zinco Headquarters, near Stuttgart, photograph courtesy of livingroofs.org

Zinco Headquarters, near Stuttgart, photograph courtesy of livingroofs.org

 Moorgate Crofts Rotherham, United Kingdom

 Moorgate Crofts Rotherham, United Kingdom

 School of Engineering, University of Auckland, NZ

 School of Engineering, University of Auckland, NZ

 Quai Branley, Paris green wall photograph courtesy of Zoë Cooper

 Quai Branley, Paris green wall photograph courtesy of Zoë Cooper

Intensive Living Roofs

Intensive roofs are essentially roof gardens.  They are generally designed for public access, high visual and recreational amenity.  These roofs create public or private open spaces for residents or workers.  The vegetation options are limitless, but as such, the cost of these roofs is high.  

Structural loading can also be an issue, as these roofs require a higher substrate depth, which in turn requires careful design considerations.  Irrigation of intensive green roofs needs to be designed for and maintenance of these roofs requires careful consideration and planning. 

The key features of an intensive green roof are...

Substrate                150mm-1500mm
Vegetation              trees, shrubs, grasses
Cost                        high
Structural loading    high
Maintenance           high


Semi-intensive

Semi-intensive green roofs can have varying depths of substrate and generally have elements of both intensive and extensive roof design.  Vegetation can comprise shrubs, grasses, sedums or mosses.

The key features of a semi-intensive green roof are...

Substrate                150mm-500mm
Vegetation              shrubs, grasses
Cost                        moderate
Structural loading    moderate
Maintenance           moderate


Extensive

Extensive green roofs have a shallow substrate and are generally cheapest to install. They have the lightest weight and as such are generally the most favoured option for retrofitting a living roof onto an existing building.

Extensive green roofs are commonly planted with sedums, mosses and grasses that are able to thrive in a shallow substrate and require minimal maintenance and irrigation.

The key features of an extensive green roof are...

Substrate                20mm-150mm
Vegetation              grasses, succulents, mosses
Cost                        low
Structural loading    light, generally suitable for retrofit
Maintenance           low


Living wall

Green walls are intentionally vegetated facades that can be internal or external to a building.  Living walls can simply be walls that have climbing plants growing on them or structures attached to the walls specifically designed to foster species able to thrive in such a condition.

We are now creating living walls deliberately as a habitat for plants, which can sustain an array of species for a variety of benefits.  Some designed systems have an irrigation system that provides water and nutrients with dramatic visual effect.