Norlite lightweight aggregate has become an established component in growing media on numerous rooftop gardens. The use of this environmentally friendly ceramic material, which weighs about 50% as much as natural planting media, in greenroof design helps address important issues such as managing storm water runoff, improving water quality, reducing urban heat, conserving energy, lowering dead load and increasing green space.
One of the most important components to both extensive and intensive greenroof systems is a quality planting medium. Because of the complex nature of greenroof construction and the difficulties of access after completion, the planting media must be able to support and sustain plants for the duration of the intended life span of the roof.
A well-designed planting medium will have the following physical characteristics:
- Is free of silts and clays that could clog the filter fabric;
- Has permanent internal aeration even after several years of consolidation;
- Ensures adequate drainage;
- Ensures stable root support;
- Does not degrade, breakdown or shrink in volume over time.
The Norlite Solution
Norlite provides a long-term solution to the above complex design requirements:
- Its reduced weight can often accommodate structural design requirements, yet it is heavy enough to avoid loss caused by excessive wind or water.
- Its angular, inert, stable and porous ceramic nature ensures an adequate supply of air to enable plants to be established quickly and develop healthy root systems.
- Ample aeration increases the insulating properties of the planting media and helps reduce energy consumption as well as lessen the urban heat island effect.
- Overall project costs are often reduced because Norlite can also serve as the drainage portion of the greenroof system.
- When used for storm water management, the porous planting medium allows rain water to readily penetrate the soil surface.This reduces runoff and allows pollutants to be naturally filtered and remediated thereby improving water quality.