As many know, next to environmental benefits Green roofs also extend the life of the roof's waterproofing.
#1 Cause of failure of waterproofing is due to thermal shock (expansion and contraction) of materials, influenced by the environment (heating and cooling of the materials).
A Green Roof (plants with growing medium underneath) shield the waterproofing form the sun, eliminating peak temperature fluctuations.
What is almost always overseen is that at the location of details, such as roof penetrations (upright waterproofing),
where there is no growing medium and plants and at the location of vegetation free zones (gravel ballast) this protective aspect is almost non-existing. The roof effectively becomes a standard roof that has a life expectancy of roughly 20/25 years. The waterproofing underneath a Green Roof could last upwards of 60 years because it is protected.
#1 Cause of failure of waterproofing is due to thermal shock (expansion and contraction) of materials, influenced by the environment (heating and cooling of the materials).
A Green Roof (plants with growing medium underneath) shield the waterproofing form the sun, eliminating peak temperature fluctuations.
What is almost always overseen is that at the location of details, such as roof penetrations (upright waterproofing),
where there is no growing medium and plants and at the location of vegetation free zones (gravel ballast) this protective aspect is almost non-existing. The roof effectively becomes a standard roof that has a life expectancy of roughly 20/25 years. The waterproofing underneath a Green Roof could last upwards of 60 years because it is protected.
| Putting this in context: A lot is invested in Green Roofs for its protective/insulating function, yet this investment could fail, at the details. |  Heat penetration through roof build |
The image above with our infra-red camera shows the heat that penetrates through a roof seen from the bottom where the blue color indicates where it is shielded from the sun, the color green where there is gravel ballast and the color red where there is exposed 2-ply waterproofing.
 | On the left you see a top view of a 2-ply waterproofing and how the migration of heat concentrates around a roof drain. Within inches a burning hot waterproofing cools down significantly (expansion and contraction). |
At time of installation the waterproofing membrane is somewhat malleable due to its plasticizers. The ongoing expansion and contraction of waterproofing and the migration of plasticizers result in the material becoming stiff.
The stiff membrane can no longer move with the motion of expansion and contraction (bridge) and thus cracks.
The stiff membrane can no longer move with the motion of expansion and contraction (bridge) and thus cracks.
BC Green Roof advanced methodology can form a continuation of the protective property of a Green Roof mitigating the negative aspects of environmental stress.
