Greenroofs — FAQs

What are green roofs?

Well you guessed it! It's a roof with some green on it! The "Green Roof (GR)" phenomenon is now catching up all around the world. It's been around since we've been around and like all things in this universe it came and went and now it's come again. It's basically a system of different components and layers which allow you to grow plants on your roof. They are broadly classified into 2 types which are Intensive and Extensive.

What are intensive and extensive Green Roofs?

Green roofing can be broadly classified under two categories. The first one is extensive which means the soil medium depth is limited (E.g. 4"). The extensive roofs are ideal for lawns and shallow rooting plants. The second is the Intensive GR. In this style the soil medium depth is much higher and hence typical ground landscapes can be replicated at the roof level. Therefore the setup and maintenance costs are much lower for an extensive Green Roof system. There are various kinds of systems and layers all claiming an advantage but the idea is the same.


What are the components of a GreenRoof?

Roof - The most obvious and important aspect we start with is the roof itself which we are going to green. The roof surface must be waterproofed in order for us to proceed. Traditionally this waterproofing was done with mortar, bituminous and tiling products. Nowadays the markets are crowded with various water proofing methods and products. The roof must be water proofed well and if time is not spent here then you are going to waste a lot of your time later.The roof must also be sloping towards the drainage points so water will flow through without any hindrance and you can avoid any stagnation. A slope of anything upwards of 3 degrees is ideal. Slopes of over 25 degrees will require additional supports at the lower end of the inclined roof.

Drainage Cells - this is the second most important component of the GreenRoof. Typical drainage cells come in about 30" thickness and can be fitted in a modular interlocking manner. They will be holding the entire load of the medium and plants so ensure you buy a good quality product. There are variations in design and some have water holding ducts. These can be used in dry and arid conditions.

Geo Textile Membrane - This is used to hold the medium while allowing water to drain through which will eventually then flow through the drainage points back to a storage tank which can be then reused. The variation comes in the thickness of the woven fabric.

Medium - Most roofs are not designed to take on too much dead load but in India it's the other way around. 80% would design and implement a strong roof and supporting columns with the idea of further expansion. Therefore one must be aware of the dead load characteristics of the roof. Soil is actually very heavy and that's why it is so stable for us to build our tall buildings. The medium therefore cannot only be soil, we must use light weight and water retaining mediums to balance the load. Perlite, Coco peat are some of the components of the medium. Most green roof companies have their own formulations depending upon the type of green roof and the local weather conditions.

Rooting membrane - This is not essential but never the less required in some of the GreenRoofs. As the name suggest the function of this component is to prevent the rooting of plants through the protective membrane.


What are intensive and extensive Green Roofs?

Green roofing can be broadly classified under two categories. The first one is extensive which means the soil medium depth is limited (E.g. 4"). The extensive roofs are ideal for lawns and shallow rooting plants. The second is the Intensive GR. In this style the soil medium depth is much higher and hence typical ground landscapes can be replicated at the roof level. Therefore the setup and maintenance costs are much lower for an extensive Green Roof system. There are various kinds of systems and layers all claiming an advantage but the idea is the same.

Can I grow trees on my Green Roof?

Yes you can but again you must be aware of what the building is structurally capable of. The trees can be planted in those areas which have supporting columns. The trees will also have to be anchored with support cables to prevent it from getting uprooted by weather factors. The pit area will also have to be covered with rooting membrane.


What are the advantages of a GreenRoof?

—The Green Roof absorbs all the heat falling on the roof surface and this allows the building to remain unaffected by the heat. This in turn will give you tremendous savings in your electricity bill. The AC will hardly ever be turned on and only a Fan would suffice like the old times. The overall Heat Island index would also reduce as studies have confirmed this in all major cities in the world.

—The roof can be converted into your own private den where you spend your quiet time and can also be used to entertain guests. There will be no need to go out when you return home since your roof garden will allow you all the privacy and comforts of home while retaining the aesthetics of say a professional garden restaurant. Water features and other elements can be added. Water can be channeled to a storage tank and reused and hence effectively capturing storm water and also recycling irrigated water.

—The value of the property goes up due to the presence of a GreenRoof.

—Its aesthetic advantages need not require any listing.

—Its acoustic properties are never mentioned in great detail but I personally think that this is one of its main advantages especially when you live in a City where there is excess noise pollution.

—The underlying roof structure life is extended as the GR cuts out all the UV radiation.

—The GR can be used to grow vegetables and herbs that you require for your own consumption. In many cities this is now being done over a large scale. Many corporations are now investing in Urban farming and Cities all over the world are actively promoting this option. Subsidies are given with respect to all the input materials and in some countries even maintenance costs are provided by the government.

—A fantastic way to get in touch with nature and cultivate gardening as a hobby for all those who live in Urban areas.


I heard it can be very expensive to install?

Used to be but now the component costs have all come down and you will be able to have a lawn on you terrace for about Rs. 150/- per sqft.

Can Green Roofs be installed on old buildings?

Keep in mind the dead load and waterproofing when you do your initial feasibility study.


I want a GreenRoof; could you install one for me?

Sure Thing! Contact us and let's get that roof of yours all greened up!