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Gaining through maintaining 

by Matt Downs

The experts at Eco Green Roofs (EGR) outline the important maintenance steps you should take to maximise the performance and ensure the longevity of your green roof.

To ensure their aesthetic appearance, design functionality and environmental benefits are maintained, it is important that regular maintenance of green roof systems is undertaken. 

At Eco Green Roofs, we recommend that regular maintenance be carried out at intervals appropriate for the type of living roof; generally twice per annum for sedum and biodiverse roofs, and between 3 and 6 times per annum for fully developed wildflower blankets. Given the investment made in the design and installation of a green roof, it is important that the system delivers its full life-cycle potential of both commercial and environmental benefits. A well-managed and regular maintenance programme will ensure longevity of performance and an economic and environmental/social return.

The main considerations to ensure the ongoing performance of a living roof are:

• Free flowing and unrestricted roof drainage

Regular maintenance of roof outlets and drainage inspection chambers will ensure free flowing and unrestricted roof drainage. It is vital that an excess build-up of rainwater is not retained on the roof to harm the living roof. Excess water will weaken root systems and allow invasive species to take over.

• An adequate amount of nutrients

The correct amount of nutrients in a living roof is important to help maintain strong and consistent vegetation growth and coverage across the whole roof area. A lack of nutrients will eventually result in bare patches across the roof and will limit the species capable of living in the system. Conversely, if it’s too nutrient rich, it will encourage excessive vegetation growth which will require trimming and cutting back to acceptable levels.

• Control of all spent vegetation, and undesirable and potentially invasive species

To maintain the balance of both species and nutrients it is important to monitor development of the plants. This involves controlling excess growth and regularly removing dead material and excess vegetation to avoid impeding drainage and leaving excess biomass on the roof which can upset the nutrient levels in the substrate and spoil the aesthetic look and design performance.

At this time of year it’s particularly important to pay attention to these elements. Leaves are falling and although some sedum and late flowering wildflowers are still in bloom, there will also be many dead-heads. All of this excess vegetation should be removed from the living roof areas. Any spent vegetation left over the winter can add unwanted biomass to the roof as it rots down, causing nutrient levels to become too high. This is particularly important to avoid on biodiverse roofs which need low nutrient systems. If leaf guards or inspection chambers are not in place over outlets, these need to be checked before the winter to make sure they are not blocked with leaf litter, which could cause leaks. It’s also the time of year when permanent irrigation systems need to be drained down, so that there is no water left in external pipework over the winter – otherwise this could freeze and burst.  

If you don’t already have a maintenance contract in place, now is a perfect time to have your green roof tidied and its condition checked, and a plan put in place for when the roof starts its growth again in the spring. Regular maintenance visits really can make a difference to the year-round health and appearance of your living roof.


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