Green Roofs: 5 Things You Need To Know About It.
Imagine walking in a park, that has soft green grass, shrubs, flowers and greenery all around you. Now imagine this park exists on your roof or your terrace. This is what it feels like to have a green roof. In the polluted jungle of concrete a green roof could be your piece of heaven.
But what exactly is a green roof?
In a nutshell green roof is a roof that has plants over it. There are mainly three types of green roofs, intensive green roofs, extensive green roofs and semi-intensive green roofs.
In this article we discuss about each of these types in detail. Plus, we will see the pros and cons of green roofs. Along with its cost estimation and other important things you need to know before installing a green roof. So, if you are planning to invest in a green roof this article is for you.
What Do You Mean By Green Roofs?
In simple words, green roofs are dynamic roofing systems designed to accommodate the growth of small plants on top of a roof. Experts also define it as, “A layer of vegetation planted over a waterproofing system that is installed on top of a flat or slightly–sloped roof.”
A Green roof system consists of many different layers. However, some of the common layers in all types of green roofs are Vegetation and growth medium, filter membrane, drainage layers, waterproofing/ root replants and roofing membrane support.
History Of Green Roofs
Did you know the birthplace of the modern-day green roof system in Germany?
However, the popular concept of green roofing dates back to 500 B.C. Babylon. Back then the most famous green roofs were the Hanging Gardens of Babylon, which were referred to as the seventh wonder of the ancient world. These were built over arched stoned roofs, and layers of thick tar and reeds were used for waterproofing.
With the technological advancements after the second world war, more importance was given to sustainable development. In the 1960s the concept of green roofing resurfaced in Germany. However, this time a more modern and practical approach was taken. A layering system was used that made the green roofs durable.
Today several countries have adopted green rooftops over traditional roofs. Beautiful green roofs can be seen in countries like American, Canada and some Asian and European countries.
Types Of Green Roofs
Green roofing systems can be differentiated based on two major factors. The amount of vegetation it can hold per square foot and the level of maintenance it may need.
There are three types of green roofs: Extensive, Intensive and Semi-intensive.
Extensive Green Roofs
These roofs are designed to have naturally low maintenance. They offer the environmental benefit we seek by constructing a green roof, but nothing else. They can hold from 60 to 150 kg of vegetation per square meter.
Extensive green roofs are best for large flat-roof buildings, apartments and low-sloped residential roofs. These roofs consist of desert grass and succulent plants. They need minimum water and after a year they do not need watering at all, just annual weeding.
If you are looking for a sustainable green roofing system that requires minimum labor, extensive green roofs are for you!
Intensive Green Roofs
Intensive Green roofs as their name suggests, need a lot of care and labor to maintain. These roofs can hold from 150 to 500 kgs of vegetation per square meter. If you are seeking floral diversity in your green roof you should go for an intensive green rooftop. As it allows herbs, shrubs, plants and even trees on it. Having an intensive green roof is equal to having an actual garden.
If you choose to have these roofs you need to look after the plants growing, separate them from one another, water them regularly, fertilization and elimination the weed. Generally, private homeowners pick this type of green roof. As they have the freedom to choose the plants they wish to grow and design the aesthetics of the roof.
Semi-Intensive Green Roofs
Semi-Intensive green roof is a sweet center between intensive and extensive green roofs. These roofs can hold from 120 to 250 kgs of vegetation per square meter. They were invented to accommodate a variety of plants and a limited
Pros And Cons Of Green Roofing Systems
Pros Of Having Green Roofs
Green roofs offer more benefits than you think. These are the reasons why you should get a green roof.
Automatic Rain Water Management
If you live in a region where the climate is unpredictable, a green roof can be a great investment. As it absorbs a majority of rain/ stormwater. This reduces your effort in managing water ponding over the roof. Plus, it lowers the stress on the drainage system.
Better Heat Insulation
Just as it absorbs rainwater it also reduces the heat conductance of the building. As its multiple layers block the heat out and keep the inner temperature constant.
Increases The Overall Lifespan Of The Roof
The normal roof has to cope with a lot of damage throughout the years. Its lifespan greatly depends upon its exposure to the elements and regular roof maintenance.
Green roofs prevent these elements from directly interacting with the outer layer of the roof. Reducing the damage caused otherwise. This increases sustainability and adds years to the lifespan of your roof. A green roof can last up to decades with proper maintenance and care.
Helps the environment
One of the most obvious reasons to install a green roofing system is to support the environment. Especially, in the urban cities, where almost 44% of total CO2 emissions are released from buildings green roofs are a great option to curb this excess emission.
Installing green roofs in cities and urban regions is one of the best solutions to increasing global warming.
Offers Wildlife Support
While we cut down forests to fulfil our needs, a green roof on houses or other buildings is a great way to help wildlife thrive. Green roofs can never replace actual grounds. However, it can still be a great place for birds and other tiny creatures to start a new life.
Depending upon the vegetation on the green roofs different species can co-exist. In a study carried out in Switzerland, 11 rooftops with varied vegetation were surveyed. They were inhabited by 172 species.
With a large number of people and animals facing the backlashes of breathing polluted air, green roofs are one step towards natural air purification in metropolitan cities.
A study proves that green roods reduce up to 37% of sulphur dioxide, 21% of nitrous acid and 0.2kg of dust particles / square meter each year.
Green Roof architecture is not just better for the environment but is extremely pleasing to look at. Green roofs not only increase the aesthetic appeal of the structure but also increase the market value of it.
Cons Of Having Green Roof
Along with their benefits green rooftops come with a few disadvantages too.
It’s no news that such a multipurpose roof is costly. A green roof costs more than a traditional roof. The primary reason is the additional support it needs to hold up the weight of so many layers plus the plants.
However, this initial investment is paid off in the future years, as this roof is more durable than a traditional roof. So, the cost of roof replacement or maintenance is less. It can be further reduced by installing an extensive green roof.
The multiple layers of a green roof make it heavier than an ordinary roof. This increased weight needs structural modifications to support it. Most of the flat roofs fulfil the requirements needed to install a green roof. However, some roofs may need retrofitting to support a green roof system.
Normally, the weight of a green roof per square meter ranges from 50 kgs to 250 kgs. In the case of the intensive green roof, it may go as high as 500kgs per square meter.
Just like any other rooftop, green rooftops need regular maintenance too. Maintainance can be a hassle if you have an intensive green roof. However, extensive or semi-intensive green roofs need little to almost no maintenance after a while.
Greens Roofs Need Insurance
All sorts of roofs need insurance to recover from unforeseeable damage. However, the insurance of green roofs is slightly more expensive than others. Due to its layering and vegetation, the cost of restoring a green roof is high and so is its insurance.
Cost Estimation of a Green Roofing System
A big part of installing and maintaining a green roof is its cost. Now, if you are looking forward to replacing your existing roof with a green roof or installing a brand-new green roof. Here is an average cost estimation of a green roofing system.
Depending upon the type of green roof you install the average cost of any green roof ranges between $10 to $30 per square meter.
This cost may increase or decrease depending upon whether you are planning to install an intensive roof with exotic plants, which are planted systemically. Or you prefer an extensive roof where the vegetation can be grown with the help of a vegetation mat and other environmental factors.
Although, the plants and materials you need for green roof construction are readily available. The cost of transportation adds to the overall cost.
Moreover, while setting a budget for your green roof, it’s most important to consider the cost of future maintenance. Depending upon the type of green roof you choose. The size of your roof and the insurance cost. All these factors together will contribute to your overall expenditure on a green roofing system.
Additional Things You Need to Know Before Getting A Green Roof
Whilst the advantages and disadvantages speak for themselves, here are a few more things you need to take into consideration before investing in Green Roofing Systems.
The life span, performance and looks of a house with a green rooftop depends on its design. There are plenty of designs of green roofs. However, you need to choose the one that benefits you the most. Depending upon your climate and surrounding.
Pick a design that causes minimum to no wind uplift. If there is too much air pressure trapped underneath the green roof when the wind blows overhead, it may cause a pressure shift, pulling the greenery off the roof.
I would highly recommend you hire a skilled contractor to install your green roof. As the installation process is intricate. If you try to do it yourself without any prior experience you may end up damaging your roof.
Roots Of The Plants
The roots of vegetation on top of your green roof may interfere with the structure of your building. To keep the roots from compromising the roofing layers below and the structure of the building, precautions need to be taken.
How Do I Know If I Should Get A Green Roof Or Not?
If you are thinking about getting a green roof, you need to have a word with certain professional individuals.
Firstly, seek a structural engineer to inspect the structure of your property. He/ she will let you know if your property is capable of supporting a green roof. If not, then what steps you need to take to offer the additional support a green roof needs? Also, he/she will let you know what precautions to take while you are setting up a green roof.
Next, connect with a good roofing contractor and get a quote. This will paint a clear picture for you. Also, consulting a roofing contractor will help you know whether you should get a green roof or not. Depending upon your location, climate, nature of your property, it’s surrounding, etc. a professional contractor will be able to guide you much better.
We hope this post had offered you a clear perspective on green roofs and cleared all the doubts you had about it. If not, feel free to drop your questions in the comment section and we will get back to you soon.
Also, if you need a roofing contractor to help you with your roofing needs contact us anytime.
Leak-Stop is a one-stop destination to meet your roofing-related requirements. We offer roof repair, replacement, maintenance and inspection services all over GVRD (Greater Vancouver Regional District).
We offer a free inspection to first-time clients. Connect with us TODAY at 1 866 777 0084 for immediate assistance!