The layers necessary for GREEN ROOF?

Question

I know there are 8 what are they and why do we need each layer. This for 2 reasons. This is a homework qeustion and i have taken nearly the hole night looking for it and cant find anything,and plus i would like to do one on our own roof.

Please and than-you!

Answer 1

If you type "green roof" into your yahoo search bar you will find that there are a huge number of sites, some of them quite informative.

Answer 2

whole -not-- hole

Thank  You -not-- than-you

Answer 3

Start with this link....   http://en.wikipedia.org/wiki/Green_roof

Also, the layers of a green roof system mimic the conditions found in nature and create an environment suitable for plant growth. Although the layers vary in thickness between the different areas, the materials used in each are similar. Even though the specific materials used in the substrate layers of the roof system vary by manufacturer, the following are general recommendations.

Drain Layer Material. Drainage layers are designed to store water for the plants to use and to regulate water runoff, but it is important to retain as much water as possible in the drain layer for the plants. It is also important that excess water can freely drain out of the system. The material should be based on:

    * structural load capacity of the roof;

    * desired vegetation per design;

    * water permeability; and

    * storage capability.

Filter Layer. A thin mat filter layer is necessary to prevent the growing medium from leaching into the drain layer. The mat filter also needs to allow roots to grow through the filter layer and into the drain layer below.

Growing Medium. The growing medium consists of a specialized soil mix. The growing medium layer must be able to retain moisture and nutrients to be absorbed and used by the plants. However, the growing medium should be porous enough to avoid build-up of excess water. The growing medium must provide firm anchorage for the plant roots and must supply the plants with essential nutrients - nitrogen, phosphorous, calcium, magnesium and oxygen. This layer should not become muddy or easily compacted, which could lead to acidification of the soil and ultimate degeneration of the plants. http://www.cityofchicago.org/city/webpor...