The concept of a roof garden is
not a new one. In fact, it is centuries old!. If you live in an
urban area, your dreams of having a garden may be difficult to
achieve. Not so if you consider a roof garden!
More and more communities are
encouraging their residents to plant roof gardens. The
environmental and psychological benefits are numerous. Not only
is gardening a calming and relaxing activity, which can reduce
stress related illnesses, it also has great benefits for the
environment. Building a rood garden on your home or apartment
building decrease storm water runoff, reduce fire risks, help
decrease heating and cooling costs and can protect your roof
from the effects of ultra-violet light and frost.
There are three types of roof
gardens and the three types related to the amount of maintenance
they require, the depth of soil and the type of plants they will
support. They are:
Extensive living roofs
These are easy to maintain and
use little soil. Extensive living roofs are lightweight and lend
themselves well for use on sheds, garages and small extensions.
As they tend to be harsh environment, suitable plants are ones
that are found on cliffs or other harsh environments. While this
type of roofs gardens are the easiest to maintain, they also
have the least visual appeal.
Semi-extensive living roofs
These garden roofs are more
decorative as they have deeper soils which can support a greater
variety of plants. However, the increased soil depth makes these
types of roof garden more heavy, so a sound structure is require
to support them. They combine the relatively low maintenance of
extensive living roofs with a more appealing appearance.
Intensive living roofs
These are full-fledged gardens
and require large and strong support structures.
One of the main considerations
when planning a roof garden is the roof itself. While flat roofs
lend themselves the best to roof gardens, it is also possible to
green pitched, barreled and domed roofs. An easy access to the
roof is also important as I am sure you would not be able to
enjoy your roof garden as much if you have to climb a ladder
every time you want to look at it. The roof must able be able to
support heavy loads. Wet soil can weight about eighty pounds per
square foot.
Make sure you install a
waterproof membrane to avoid ending up with a wet ceiling. The
two most commonly used materials are thermoplastic sheeting or
rubberized asphalt. As I am certain that you will not want to
dig up your garden to replace the membrane every few years, make
sure you select a product that is extremely durable. The next
layer should be a filter sheet that will allow the moisture to
drain off the roof while ensure that the fine material do not
escape. Next comes the moisture blanket which will ensure that
an extensive live roof garden has enough moisture to support
life. Commercial ones can be purchased however it is also
possible to use cardboard or old blankets to the same effect.
The following layer will be a
drainage layer. Similar to the moisture blanket, it will help
retain moisture while allowing excess water to drain away. They
are usually made of plastic or geotextile materials. The top
layer will be the soils and substrates. These should be
lightweight and freedraining yet retain moisture. One such
option is an aggregates mixed with light sub-soild such as
crushed porous brick or limestone chippings. Finally come the
seeds and plants. The possibilities are limited only by your
imagination and the environment. Happy gardening!
