A roof garden, also known as a green roof, is a roof over a living space that supports a garden or lawn.

An increasing number of building owners are asking for roof gardens due to their aesthetic and environmental benefits such as storm water control, sound insulation and energy conservation.

An upside of this growing interest has been the increase in the number of roof garden systems entering the market. The downside is that several of them have been pieced together with independent components sourced from different suppliers which haven't been tested and proven as a coordinated system. Furthermore, some components haven't been specifically designed for a roof garden system. Examples of roof garden shortfalls (and therefore traps to look out for) include:

• The use of mainstream torch-on membranes without inherent anti-root treatment
• Using normal topsoil from a building merchant (which eventually bakes into a crust) versus the pumice / perlite / compost growth medium mix specially formulated for roof gardens
• Inferior drainage design (e.g. poor soil and an absence of ballasting causes blocked drains)
• Inappropriate planting e.g. plants with aggressive root structures (e.g. flax) versus roof garden-friendly vegetation such as sedums and aloes

The consequences of poor research and not strictly abiding by a supplier's empirically tested and proven system are obvious and extremely dangerous. 100% impermeability is not negotiable. The expense involved in rectifying a leaking roof garden is astronomical.

A typical roof garden system is comprised of the following components:

• Concrete substrate
• Waterproofing membrane system installed to the Building Code (if torch-on membrane is used, two-layers with anti-root treatment are required)
• Protection fabric (Geotextile)
• Heat-weldable polypropylene root barrier (if the membrane below it is a single-ply membrane)
• Drainage board composite (small dimple cups to retain water)
• Moisture retention fabric (Viking Roofspec's is already factory-applied to the drainage board)
• Growth medium (specialised roof garden soil mix for maximum drainage and plant nutrition)
• Roof garden-friendly vegetation (e.g. sedums, aloes)
• Ballast stones for around the inside roof perimeter and for surrounding drains with non-ferrous leaf and gravel grates
• Optional extras — aluminium drainage protection boxes and edging (between ballast and soil)

With this many components, it is important that each has been tested and proven to work by the manufacturer, as part of a coordinated system. This is the strength of Viking Roofspec's Roof Garden system: the specification of which has been proven locally and around the world.