Green Roof Drainage Design

The design of the different drainage layers allows for a portion of the stormwater to be retained above where the water is allowed to flow freely off of the roof.

Green roof drainage design. These are collector drains that are designed to flow when only partly full. Urbanscape green roof is a complete system which consists of a root membrane a drainage system a growing media a unique patented rock mineral wool and a vegetation layer. Intensive layered green roof intensive green roofs have a deeper soil depth therefore the roof drain enclosure height is typically 12 or more. Z110 green roof drains are available with enclosure heights ranging from 5 to 18 or as specified.

Z110 green roof drain shown with 18 height for intensive green roofing applications. Primary drainage systems are not designed to remove all of the water that falls on a roof during exceptionally heavy rain. The filter layer on a green roof is designed to prevent soil and other substrates as well as debris from filling the cavities of the drainage membrane. Dead and imposed loads should be calculated in accordance with bs en 1991 1 1 be en 1991 1 3 and bs en 1991 1 4 and should include the weight of the waterproofing system saturated weight of the green roof components and substrate vegetation snow loads and imposed loads such as access by people and vehicles as well as point loads for.

Urbanscape extensive inclined up to 20 and pitched green roof systems 20 45. A green roof may require a separately plumbed secondary drainage system also known as the overflow relief system. Both of our permaseal 20p green roof and permaseal 8 green roof drainage membranes have a build in geotextile filter layer making the installation process that much quicker.