Frequently Asked Questions
about Green Roofs
Load bearing capacity
3. What is the weight of a green roof?
Green roof weights vary depending on the thickness of the build-up.
A thin layered extensive green roof, when saturated with water, will weigh between 18-30 lbs/sqft.
This can be roughly equated with a typical roof covering of gravel. A gravel covered roof will weigh around
12 lbs/sqft. Therefore, the typical roof of gravel can easily be replaced by an extensive green roof.
On the other hand, an intensive green roof requires a higher load bearing capacity. Depending on the build-up height, weights for intensive roofs can range from 60-80 lbs/sqft.
Calculations: When calculating the load bearing capacity, building architects and civil engineers are able to provide the necessary information. Often, roofers and carpenters are also able to help with these calculations.