REDUCED STORM WATER RUN-OFF

The reduction in storm water run-off offered by green roofs is a major benefit. From the results gained by practical trials, the average extensive system can absorb approximately 50% of the rainwater falling on it, and also significantly delay the passage of the remaining water, reducing the pressure on drainage facilities and flooding.

Intensive systems incorporating sufficient soil depth to support planting schemes, can retain up to 75% of rainfall. Tests have also indicated that greater soil depths may retain up to 90% of rainfall.

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