A green roof is an engineered system that must meet basic roofing requirements. The system includes ...

1. Green Roof Components
A green roof is an engineered system that must meet basic roofing requirements. The system
includes layers that protect the building from leaks, allow excess water to drain, retain sufficient
water to support the vegetation, prevent plant roots from penetrating the roof membrane, and, in
some cases, insulate the building.
Green Roof Components
Green roofs typically include the following components:
Waterproof Membrane
This membrane is applied to the building surface and keeps water from leaking into the building
construction. It can be applied as a liquid or in sheets and must be applied correctly and
meticulously to avoid damage to the membrane. In some cases, the membrane will also contain a
root barrier either as a laminated surface or through chemical additives in the coating. Once the
membrane is applied, it is important to thoroughly test the impermeability of this layer and repair
any damage or leaks before continuing with the installation.
Root Barrier
Some plant roots are aggressive and, if unimpeded, can penetrate the roofing membrane and
damage the roofing system. This layer prevents plants from growing deeper into the roofing system
and protects the waterproof membrane from damage.
Insulation
By adding a layer of insulation, the green roof is better able to regulate the interior temperature of
the building and reduce the amount of energy required to heat and cool the building. In some cases,
the insulation layer is integrated with the drainage layer. If applied as a separate layer, it can be
installed under or over the roof deck or directly over the waterproofing membrane.

2. Drainage Layer
Excess water must be able RoofingNewarkOhio.com to drain from the roof to prevent the growing
medium from becoming oversaturated. The drainage layer must handle surface water, subsurface
water, and transporting water from the roof to gutters and downspouts. The
http://dictionary.reference.com/browse/construction type and size of the drainage layer depends on
the type of green roof being installed. For example, an intensive green roof generally needs more
drainage than an extensive system. In extensive systems, this layer is critical for flat roofs, but may
not be necessary for sloped roofs where gravity helps to move the water toward the drains.
Holding Cups and Retention Mats
In reservoir systems, a layer is added to store excess water for later use. This layer reduces the need
for irrigation. Water collects www.RoofingNewarkOhio.com in these cups or mats and is available to
the plants during dry weather. This layer has the added benefit of reducing the amount of runoff
from the roof.
Filter Mats
These mats hold the growing medium in place and prevent small particles from washing out to the
drainage layer and clogging the drains. They may be integrated into the drainage layer or installed
separately.
Growing Medium
The plants are supported in a growing medium, not soil. Growing medium is an engineered
substance that provides the necessary nutrients for the plants, absorbs and drains water efficiently,
and is light in weight. Growing mediums are designed and tested to suit specific growing conditions
and requirements. If they contain too many organic compounds, these compounds will break down
and leach into the runoff water, which can be damaging to both the green roof system and to the
neighboring wildlife habitats.
Vegetation
The type of plants used for the green roof depends on the type of green roof installed, as well as the
climate zone, amount of growing medium, and the green roof design. An extensive green roof
generally uses drought resistant plants with shallow roots, e.g., sedums and grasses. Intensive green
roofs may use any plant, including shrubs, perennials, trees, and so on.
Irrigation
In addition to these layers, green roofs may need an irrigation system. The need for irrigation
depends on the type of green roof installed and the climate zone. Intensive green roofs will need
regular irrigation. But, some extensive green roofs do not need to be irrigated once the plants are
established.
Despite variations in green roof designs, the components help to ensure that the roof functions
efficiently and meets building and environmental requirements.
Additional Information

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