about

green roofs

Who cuts the lawn?
First and foremost, not all greenroofs are grass, sod or turf roofs. In fact, the modern greenroof is most likely NOT a grassroof. This is because grass roofs require more soil than an average lightweight greenroof which means they are relatively heavy. And, unless someone does keep them cut, grass roofs tend to get shaggy which doesnt have an aesthetic appeal for everyone. When we do use grass for our roofs, we use a low-growing fescue that stays neat without a lawnmower. An average extensive greenroof requires no lawnmower and generally requires maintenance 1-2 visits annually once established.

Will the roof always be green?
No. Green roofs ARE living roofs and just like a garden, a greenroof has its seasons. During a year, a greenroof may go from green to pink to autumnal orange to brown.

Can you retrofit buildings?
Absolutely, you just have to make sure the structure has the load bearing capacity to support a greenroof.

Can I just put soil from my garden up onto the roof?
It is generally not recommended. Regular topsoil is heavy, inconsistent and full of weeds. Greenroof substrate is engineered to be as lightweight as possible, maximize water attenuation and provide the right amount of nutrients for the vegetation being used. Regular topsoil can be appropriate for brownroofs where the goal is to maximize use of local and recycled materials as well as encourage native species.

What maintenance is involved?
An average extensive greenroof requires no lawnmower and generally requires 1-2 maintenance visits per year. This will vary depending on the time of installation, irrigation, plant selection, visibility and soil depth.

Do I need irrigation?
Greenroofs can be designed to thrive without irrigation although it is always recommended to have a source of water close to the roof during the initial establishment period. Irrigation depends on the design intent of the roof as water availability in the greenroof can impact the effectiveness of the roof to perform certain design objectives.

Are greenroofs good insulators?
Greenroofs have a more significant effect on keeping buildings cool in warm climates. Greenroofs keep the surface of the roof cooler externally which results in less heat flus from the outside (hot) to inside (cool). As insulators, green roofs must have a minimum of 6” (150mm) depth of growing medium before any siginificant impact is made on cost savings and R-value.

Are there proven, science based standards for green roofs?
Yes. The German Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau. e.V. (FLL) has produced an extensive and comprehensive body of guidelines for greenroofs which are the most widely accepted standards for greenroofs to date.