Dec13

Green Roof Maintenance Hints and Tips

Posted by david.luukas

guy-on-green-roof1Blackdown Greenroofs appreciate that right now, in the depths of winter, maintaining your green roof is probably the last thing that you’re thinking of, but it won’t be long before spring will be pushing ahead and making us think of those important tasks.

By their nature, extensive green roofs are low maintenance, (that’s low maintenance, not no maintenance) unfortunately, it seems in a lot of cases, green roof maintenance is overlooked or considered un-necessary, this is just not the case, after all this is a living system which is trying to flourish in what can be a very hostile environment.

So, here’s a few hints and tips to encourage us to start thinking of what’s required and with a little help from us your green roofs should continue to develop to create a self-sustaining plant community for years to come.

building-green-roofFoot traffic

Light foot traffic on the planted roof, 2-3 times a year, should have no detrimental effect on the plant layer, However, if it’s going to be more frequent than this then consider a hard surface or a least a gravel pathway.

Removal of undesirable plant material

Some people welcome the colonisation of so-called ‘weeds’ to promote biodiversity. However, you may rather have them removed. Timing their removal before they set seed is key to helping keep on top of the weed population and reduce the weed seed bank in the substrate – easing the subsequent build-up of years of weeding!

Application of nutrient

The levels of nutrients available within the green roof substrate will vary from season to season and from year to year. When replenishing them, it’s best to try and use a low nitrogen fertiliser so as not to encourage rapidly growing broadleaf plants at the expense of slower growing wildflowers and sedums. Understanding the N:P:K ratings on your fertiliser is an important aspect of greenroof maintenance.

pink-flowersCorrection of system

Over time acidification of the growing medium can occur. This can happen particularly in built up areas where rainfall can be slightly more acidic. Acidified growing mediums can encourage the establishment of moss. Low levels of moss are not a problem and indeed should be viewed as a significant part of the roofs biodiversity. However, if moss becomes too well established this could be at the expense of other preferred plants.

Checking of gutters and outlets

This should be carried out routinely during any maintenance check to ensure drainage and rainwater outlets are not impeded.

Removal of leaf litter

The ideal position for a sedum green roof is in full sun. However, if adjacent trees shed their leaves onto the planted roof surface this could have a detrimental effect upon sedums. Its best to try and remove any buildup of leaf litter soon after they fall.

Safe access

We all want to work safety and ensure our friends and colleagues are not put at risk. 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.

All inspections/and or maintenance actions carried out on the greenroof must be in full compliance with the appropriate health and safety regulations, and particularly those specifically dealing with working at height.

Refer to current HSE publication ‘The Working at Height Regulations’ for further guidance.

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