Installing a green roof, whether it is on an office building, apartment, or residential home is a great way to go green and help the environment around you. Before installing a green roof though, there are some considerations you should keep in mind; specifically, you should consider the facts behind intensive vs extensive green roof.
Extensive and intensive green roofs are quite different from each other, and what may work for one building won’t work for another. In general, Intensive green roofs allow for more variety, but are expensive and require much maintenance. In contrast, extensive are cheaper and easier to maintain but are limited in what they grow.
In this article, we will look over the differences and pros, and cons of intensive and extensive green roofs so that you can make an informed decision on which type you want to use for your location. In addition, we will discuss Smart Gravel, our product here at Arqlite, which provides a vital part of any green roof: perfect drainage.
The Differences Between Intensive and Extensive Green Roofing
Let’s begin our discussion of an intensive vs extensive green roof with a look at some of the differences between the two. That way, you can get an understanding of what one may work best for you.
According to the National Park Services, an extensive green roof’s growing medium is shallow, most often six inches or less (1). The roof requires a smaller load, and thus the diversity of plants that can be incorporated is limited. The benefit of this though is that the need for watering is often limited. They often work best in places like residential homes and thus the roof is often inaccessible.
In contrast, Intensive green roofs often require a deeper growing medium, usually around 8”- 30” deep (2). Because of their depth, they can host a variety of plant life. Hydroponic gardening can also be incorporated into an intensive green roof. They are essentially perfect for rooftop gardens on the tops of office buildings, apartments, and other such locations. They are usually accessible too! Unfortunately, though, they are often out of the scope of the average homeowner.
Whether you go intensive or extensive, they both do share some advantages. For example, they aid in insulating the structure they are on. Thus, you may be able to save money on heating and cooling your building or home. In addition, they both foster the eco-friendly lifestyle that many are trying to achieve in an age when sustainability is becoming a greater concern.
What Are the Pros and Cons of Intensive and Extensive Green Roofing?
Now that we know more about the intensive vs extensive green roof consideration, let’s look at the pros and cons of each. It is important to know these so that you make an informed decision on what one will work for your location and your lifestyle.
The Pros of Intensive Green Roofing
One of the biggest benefits of an intensive green roof is the variety of greenery that you can plant in it. Because of this, it can result in a very aesthetically pleasing look (3). This makes it perfect for an apartment or office building roof, as it gives people a nice and relaxing place to spend time
In addition, it opens great gardening spaces for those living in cities with limited agricultural areas. This is great for apartments in particular, as it will foster community projects and allow the residents to grow their produce.
If you are interested in hydroponic gardening, that can also be incorporated into a green roof as this chef did in New York City (4).
The Cons of Intensive Green Roofing
One of the biggest cons of intensive green roofing is the cost of installation. This is not a DIY project, and you will need to hire a company to install it on your building. Installation costs about $30 a square foot depending on your location (6). This tool can give you an idea of the cost of your project.
Because they require deep soil, you also need to make sure your roof can sustain a weight of 35 to 100 pounds per square foot (2). This is why they will often work best on a location like an apartment since the roofs are generally able to hold a heavier weight.
Now, depending on who you are this may be an advantage for you. But these do need more maintenance since they are often supporting plants that require care and attention to grow well. You will also need to make sure that any walkways are clear, to ensure that no one on the roof gets hurt.
The Pros of Extensive Green Roofing
One of the pros of extensive green roofing is that they are low cost, and easier to install. It can be a DIY project. So, if you love gardening, building, or both, this can be a fun project to undertake! Looking at cost, an extensive green roof starts at around $10 a square foot (6).
Another great aspect of this type of green roof is that it is lighter than its counterpart, weighing around 10 to 25 pounds per square foot. Despite their lower weight, if you install one yourself, make sure to do the math. You don’t want to damage your roof by making your green roofing too heavy.
Another potential advantage is that they often require little maintenance as the most popular thing to grow is succulents. Unlike their counterpart, some extensive roofs do not even need permanent irrigation (7)! Thus, if you are a residential user, you can have an eco-friendlier lifestyle while still giving your landscape and garden the attention that it deserves.
The Cons of Extensive Green Roofing
The biggest disadvantage is for those whose primary goal is a stunning aesthetic in their gardening, landscaping, and building. Although an extensive green roof can be made to look nice, the foliage on top will usually be grasses, moss, and sedums. You cannot get the same diversity as an intensive roof.
Another potential issue you may face is leakage. Although this can happen on any green roof, this may be more troublesome, especially for a homeowner on a budget (8). Roots can break the waterproof membrane, and thus, water will leak into your home. Don’t be discouraged though, there is a great way to protect against this!
Use Arqlite Smart Gravel as your Green Roof Drainage Layer
Now that we have covered the debate of choosing an extensive vs intensive green roof, we need to cover something that all green roofs need: a drainage system. There are several layers to a green roof, some of which include (1):
- Vegetation
- Growing medium
- Filter membrane
- Drainage layer
- Waterproof/root repellant
The drainage layer helps to make sure that excess water is not trapped on the roof, which could cause strain on the system. It helps to filter water down the slope of the roof, towards the edges and drains, allowing the water to wash off.
The best drainage option for green roofs is Arqlite Smart Gravel. Smart Gravel is 3x lighter than mineral gravel and a 10x better insulator. When used on a green roof, Smart Gravel acts both as a drainage layer to prevent leaks and an insulative layer to help reduce HVAC costs. It also reduces the weight load on the roof, a huge goal of many architects. Smart Gravel is an eco-friendly, low carbon artificial gravel made from 100% recycled plastics. It is easy to install at heights and perfect for green roofs!
In Conclusion: Intensive Vs Extensive Green Roof
In the debate of the extensive vs intensive green roof, the choice you make will depend on your budget and the type of infrastructure that you have. If you have a big budget, and a roof that can withstand massive amounts of weight, then an Intensive green roof is a great choice. If you have neither, then extensive is a great way to go.
If you decide to have a green roof, don’t forget to use Arqlite Smart Gravel as the drainage layer! It is a great choice especially if you are looking for an eco-friendly lightweight material to use!
