As an exotic treatment for hotels and large office buildings, rooftop landscaping creates an environment like no other. With a spectacular view, and the sense of being “above it all,” these special venues conjure a rarified ambience.
Advantages are Many
From a utilitarian perspective and most importantly, they are GREEN, performing an environmental service by reducing the urban “heat island” effect, as well as providing the meritorious function of mitigating pollution. When homeowners make the decision to landscape their roof, an immediate benefit is the reduction of air-conditioning expenses in Australia’s tropical zones.
Landscaped roofs act as sound insulation. They can be designed as rain collectors, to reduce the load on city storm-water drainage systems. Moreover, the vegetation provides habitats for birds and absorbs negative air toxins that pervade the urban atmosphere. Protecting the roof from damaging U.V. rays, landscaping extends the life of the roof and does what landscaping often does at ground level: hide the mechanical equipment.
Aesthetically, the greatest advantage is being free of encroaching design influences. The designer has the latitude to create a realm of enchantment for this venue. Limited only by the owner’s willingness to accommodate the design in his budget, the architect can create with abandon—even bypassing certain water conservation restrictions that loosen to the extent the roof can compensate.
Disadvantages Can Be Overcome
Normally, rooftop gardens require higher maintenance costs. However, with concepts that offset these costs, they can be held to a minimum. Complex drainage systems are often blamed for abandoning the opportunity. Flat roofs involve inherently complex drainage systems; carefully designed roof gardens can take advantage of how these drains function.
Winds are often the cause of damaged or disappearing vegetation. A design solution is waiting in the wings. The supporting structure will need to be reinforced. Finding and repairing leaks are possibly problematic.
The minimum rate for landscape roofing is $8 per square foot. $12 to $24 per square foot exceeds the cost of most built-up roofs from five to ten times. However, in considering initial costs, the owner should be made aware of the GREEN tradeoffs as well as an ROI that may take some time to realize, but with commercial square footage at a premium, can occur sooner rather than later. Hotel as well as business proprietors are aware that such an amenity yields benefits that cannot be measured on a ledger sheet.
Maintenance costs are usually the result of prolonged neglect or using fast growing plant materials. With a bi-monthly schedule, slow-growing, water-less materials, and no-maintenance design objects, the roof garden will not be a high-maintenance item. Handling drainage can be accomplished with one of several approaches:
- a shallow retention pond
- garden rain collection points connect to current roof drainage hubs
- garden rain collection points are designed to pipe rainwater to a rooftop reservoir to water this site.
Protect delicate vegetation with one of these:
- perimeter glass
- plant container barriers
Flat roof mounting systems, acting as purlins, ideal for containing and supporting building services and equipment, can also be designed with integrated roof access and under floor access. They can be altered to suit an array of requirements and support services.
Leaks can be prevented with an elastomeric underlayment, undisturbed while covered with a garden. Careful maintenance records will track staff maintenance activities. It’s also a smart idea to cover the area with taping monitors.
With the advantages, costs and disadvantages handled, it will be a pleasure to see more of these spectacular installations going up on roofs around the country.
If you have any thoughts or suggestions, feel free to share them in the comments below.