Maintaining your green roof using temporary irrigation

Posted by david.luukas

One of the most common causes of green roofs underperforming is insufficient application of irrigation immediately after the plants have been installed. With the UK’s variable weather conditions we can experience long periods of unseasonably dry weather when normal levels of rainfall cannot be relied upon to provide sufficient moisture for the plants to establish into the growing medium.


Irrigation systemTherefore, Blackdown Green Roofs recommend a period of temporary irrigation directly after planting for all extensive and semi-intensive systems to ensure the newly installed green roof has the best possible start in life. Without this short but important period of irrigation – usually between 6-8 weeks – a green roof will struggle to establish, be more prone to erosion, and could look less visually appealing. Once this period has expired the irrigation is removed and the system will support the plants without further intervention. The only exception to this is when a roof has a pitch of more than 30 degrees.

Blackdown has a variety of irrigation systems to suit a range of roof areas, whether it is ten or ten thousand square meters.


Irrigation systemOur Systems

1. are fully or semi-automatic so that once set up they will irrigate a roof without any input from the client

2. are small enough to be carried up internal stairs, external hoists or even lifted through windows

3. require mains water i.e. a roof or ground floor ¾” bib tap

4. can operate from 110 or 240v power or, if either of these aren’t unavailable, a 9v battery




irrigation system by BlackdownConstruction, Design and Management Regulations

Under the Construction Design and Management Regulations (CDM) 2015, appropriate measures should be taken at both design and construction stages to ensure safe access and passage over the planted roof areas for maintenance personnel.

Health and Safety

It is strictly the contractor’s responsibility to ensure all works are executed in accordance with current health and safety legislation. Guidance must be taken from relevant and current HSE publications. Refer to current HSE publication ‘The Working at Height Regulations’ for further guidance.


Irrigation systemAccess and Egress

Access and egress routes to/from the roof need to be carefully considered. Ideally, these should be discussed and agreed between client/end user and Blackdown Green Roofs before completion of the installation phase if an irrigation contract is required.

Safe access across the roof could take the form of perimeter balustrade, a post and wire fall prevention system or a collapsible roof perimeter handrail.

Should you wish to discuss your project requirements with Blackdown please contact us on 01460 234582


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White House Works, Bold Road, Sutton, St Helens, Merseyside, WA9 4JG