Growstones and Green Roofs: Perfect Together
Growstones are a highly porous aggregate media made from recycled glass which is emerging as a highly desirable alternative to commonly used green roof media. Its porous yet rigid structure delivers a lightweight media with high aeration and fast drainage, good water holding capacity and resistance to freeze thaw cycles.
One of the most important characteristics for any green roof media is the weight or bulk density of the media both dry and wet as this impacts the dead load associated with the green roof. The weight is particularly important for retrofits where a green roof will be installed on an existing building with limited load bearing capacity.
The average bulk density of Growstones blended media is only one fourth (dry) and less than half (wet) compared with other commercial green roof blends with media such as expanded slate, shale, clay and sand (Berghage, 2012).
Any green roof media also needs to support the growth requirements of a diversity of plants within a wide range of climates from rainy to dry. Fast drainage and reasonable water holding capacity at field capacity of Growstones blended media at different ratios allows for high adaptability (flexibility) to different precipitation levels, drainage needs. It also supports rapid plant growth and fast full roof coverage.
As such and especially owing to its characteristic lightweight, Growstones blended media has the potential to widen the range of buildings able to receive a green roof, which were previously not eligible due to limited load bearing capacity.