Green Roof Basics
Whilst green roofs have been around since biblical times, the development over recent years of the lightweight systems which are now most commonly used in the United Kingdom has led to a substantial increase in the number of buildings where it is practical to consider their use.
From originally being specified for their amenity and appearance benefits, green roofs are now increasingly being demanded to help meet planning objectives for sustainability, ecology and storm water management on both new and refurbishment developments. Arising from the dramatic increase in demand, and to meet a wider range of performance criteria, Bauder has substantially expanded its product offer over time to enable us to deliver a complete range of system solutions and meet any foreseeable future requirements.
Whilst there are many different terms for the types of green roof currently being specified, they all fall into the general classification of either an “intensive” or “extensive” installation.
Intensive Green Roofs
A traditional intensive green roof installation can best be described as one which is intended to mimic the appearance of a traditional amenity landscape, such as a park, terrace or garden. It is often constructed over the roof of a “buried” structure and can be blended into the surrounding landscape. Whilst the hard landscaping and vegetation can be whatever the client wishes, the height to which the plants and trees are required to grow will determine the depth of growing medium, the level of irrigation required and the planned maintenance needed to keep it looking in good order.
Extensive Green Roofs, including Brown and Biodiversity Roofs
The term “extensive” is applied to lightweight, low maintenance installations where access is generally required for maintenance purposes only. The mix of vegetation will vary from sedum through to drought tolerant wild flowers, herbs, alpines and grasses and may also include some hardy shrubs and perennials. The substrate depth, irrigation and maintenance requirements will vary significantly, dependent upon the type of vegetation specified and its purpose, but will be significantly less than those for intensive green roofs.
When planning to specify a green roof the key considerations should be:
- How is the green roof system to drain
- What purpose is the green roof to serve
- What is the visual requirement
- What level of access will be required
- What load will the structure support
- What is the budget for the installation
- What is the budget for maintenance
Once the answers to the above have been decided upon it is a relatively simple process to consider the range of suitable options and determine which is best suited to the project requirement.