Green Roofs - Living Architecture Monitor - Winter 2010 - (Page 28)

BEST PRACTICE MAINTENANCE MATTERS FROM HELPING TO GUARANTEE A WARRANTY TO ENSURING THE PLANTS PERFORM AS DESIGNED, MAINTENANCE OF A GREEN ROOF IS CRITICAL TO SUCCESS By Terry McGlade he green roof industry has always discussed maintenance as being important but recently, it has become a focal point – and for good reason. Maintenance for green roofs involves scheduled visits during which service professionals typically perform weeding and fertilization, inspection and cleaning of roof drains, looking for signs of the presence of vermin, assessments of plant material for stress or disease and, when applicable, a check of the irrigation system. Maintenance is especially critical during the establishment period of the green roof; the passage of time until plant material reaches 80 percent coverage of the allotted “green area”— typically two years. Maintenance visits need to occur more frequently to ensure the success of the green roof during the establishment period. Maintaining a green roof serves a number of important purposes including ensuring the desired aesthetic is reached and maintained, for a warranty requirement, and roof and building safety. Green roof plants are living organisms and therefore require water and care. However, unlike plants on the ground they are exposed to higher temperatures and more extreme environmental fluctuations, and therefore are more susceptible to stress. Maintenance on green roofs is also about establishing and analyzing the critical needs of the plants. Maintaining the aesthetic of the green roof involves ensuring that plants receive appropriate amounts of water, especially during the first three months, ensuring that weeding takes place frequently during the first two years (after about three years, the penetration of weeds will be limited if green roof plant coverage has been estab- T lished fully) and providing nutrients in the form of organic, nonchemical fertilizers. Maintenance is considered part of most green roof warranties. Standard express warranty (warranties that are specifically expressed by the seller of goods ) cover the green roof for two to three years however the maintenance best-practice standard is increasing to five years, whether warranties will change to reflect this is yet to be seen. The production and submittal of maintenance reports is generally required in order for the warranty to remain valid Finally, maintenance is crucial to ensure that the green roof is functioning correctly which in turn keeps your building and roof membrane safe from any potential harm. By regularly performing maintenance, checking roof drains, removing weeds and saplings, ensuring adequate hydration and identifying any dead areas you will protect the roof from flooding and potential damage to the membrane. To adequately address the maintenance needs of green roof maintenance plans, allocation of maintenance budgets should happen during the planning stages, not as an afterthought. In order to plan adequate maintenance, it is imperative that each specific system’s maintenance requirements be considered. Modular systems, mat systems, seeded systems, plug systems and cutting roofs all require different levels of initial maintenance and this must be factored into the maintenance schedule especially during the first three months. These different systems, due to their varying needs, will also affect your maintenance budget, so again this is best taken into consideration at the planning stages. The City of Toronto’s new green roof construction standard requires the submission of a maintenance plan as a TOP 3 M AI NTENA NCE TI PS 1. ACCESS TO ROOF LOCATIONS Access to green roof sites can prove extremely difficult so designers need to ensure adequate access. Access issues must also be built into maintenance plans and budgeting. Maintenance staff need to ensure appropriate, legally required safety precautions when accessing roof sites. 2. SUFFICIENT WATERING OF PLANT MEDIA DURING ESTABLISHMENT PERIOD Maintenance visits/irrigation should be scheduled once a week during the first month after installation, once every two 28 LIVING ARCHITECTURE MONITOR weeks during the second month and once a month during the third month. Adjust this watering recommendation if rainfall has occurred. It is best to physically check the moisture of the growing medium rather than simply relying on a schedule. In colder climates, there is a recommended do not water period which is within one month of the expected average frost date (usually there is plenty of moisture during this time of year, too much water will compromise the plant material’s ability to survive over winter). 3. AIRBORNE SEEDS Airborne seeds can introduce weeds, tree seeds and volunteer plant species to a roof. The removal of weeds and tree seeds is critical for the survival of the green roof plants as well as the safety of your roof membrane (trees have invasive root systems and can penetrate root barrier systems that were not designed for that situation). Remove weeds early, and make sure you remove the whole weed including the root. Wet the ground around the weed and your job will be easier. Any weed seeds left and then exposed to the sun will begin to germinate, so make sure not to break open seed pods when removing weeds. If you leave volunteer species on your roof, within a season you will have a vastly different green roof aesthetic. WINTER 2010

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Winter 2010

Green Roofs - Living Architecture Monitor - Winter 2010
Contents
Laying Roots for Green Jobs
Outstanding Student Design
Passing of a Legend
New Federal Stormwater Guidelines From EPA
Partnering Science with Service
On the Roof with...Eden Brukman, Reg. Arch., LEED(R) AP
The Leaf Effect
Who Owns the Green Roof?
Planting the Federal Inventory
Curb Appeal
Maintenance Matters
Professional Development Update
Professional Calendar
Congratulations New GRPS
Welcome New Corporate Members
Green Roof Energy Calculator
Doing No Harm

Green Roofs - Living Architecture Monitor - Winter 2010

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