A green roof, also known as an eco-roof or a living roof, is a carefully designed roof completely or partially covered with a layer of vegetation and plants. It’s one way to put an often-neglected space to good use. This is a new concept that’s gaining popularity, mainly on account of the various environmental benefits it offers, similar to living walls.
There are mainly two types of green roofs to choose from depending on the depth of soil – extensive or intensive green roofs. Extensive green roofs have a soil depth of fewer than 6 inches and don’t require much maintenance or irrigation. These are usually installed in spaces where there will be no people walking on the roof, like on sheds or multi-residential buildings. On the other hand, intensive roofs are seen on commercial buildings to provide park-like settings, where a person gets to interact with nature. A greater soil depth means that it can be used to grow large plants, which is not possible in extensive roofs.
It’s ideal for installing a green roof when you’re looking to replace your old roof. But if your existing forever metal roof has excellent waterproofing, you can convert this into a living roof easily. No matter the type, and it’s ecological and general pros, installing green roofs also comes with its own set of disadvantages.
This article will cover both the pros as well as the cons, so you can decide if a living roof is the right choice for your business or home.
Advantages of green roofs
1. They are aesthetically pleasing
Converting your dull-colored roof into a lively green space abundant with little plants makes your building more attractive to those viewing it from a distance or living above it. This is especially true in an urban setting, where converting ‘wasted’ space into a beautiful garden can even add to the overall value of your property.
2. They reduce stormwater run off
When storms occur in cities, the hard rooftops of most buildings increase the velocity and volume of rainwater. This is the primary reason for pollution and flooding everywhere. The growing media of green roofs, along with its plants, can absorb, retain, and purify this water and later return it to the atmosphere through transpiration and evaporation. By this, localized flooding can be prevented.
3. They provide natural insulation
Green roofs are very effective at regulating temperatures and providing a natural form of insulation. During the summer months, it shields your home from direct sunlight, thus keeping the inside cooler. During winter, it helps minimize heat loss from the building, thus keeping your home warmer.
So, this way, if you have a green roof, you will be saving money on air-conditioning and heating costs. If your commercial building has a green roof, this could mean significant saving in energy costs. Consequently, it also means decreased greenhouse gas emission and air pollution.
4. They extend your roof’s life span
Green roofs might work out to be pricier when compared to a regular metal roof both in terms of installation and maintenance, but it’s an investment you make because of the duration they help your roof to last. A layer of vegetation over your regular roof gives it a longer lifetime, up to 60 years, as they protect it from external elements.
5. They support wildlife
Green roofs create a healthy habitat for small wildlife and birds, like insects and butterflies. Depending on the kind of vegetation, quite a few birds struggling for survival can use it to raise their young ones. They might also act as a stopover connecting natural habitats. Adding biodiversity to your roof can also prove to be an additional source of income if you were to start something like a bee colony on your green roof.
Disadvantages of green roofs
1. High-cost upfront
While it is true that green roofs save you a lot of money in the long run in the form of lesser energy bills, it costs quite a bit to set it up in the first place. Installing an extensive green roof can cost up to £12 per square foot, which is twice the cost of getting a traditional roof. If you’re thinking of getting an intensive green roof, which has a more complex assembly, expect to pay even more. Maintaining these can be pretty expensive and labor-intensive, too.
2. Increased weight load
Green roofs add a lot of weight on top of the existing roof – sometimes even up to 200 kg/meter square. The walls and roofs of some buildings might not be tough enough to take on this added weight. This might be especially true in the case of intensive green roofs, which are heavier and thicker, and thus require adding extra structural support. Extensive green roofs are lightweight and thin when compared to their counterparts, but they can only be installed on roofs that are flat or have a slope less than 25 degrees.
3. Possibility of damage from leaks
A lot of planning goes into installing an eco-roof to make sure that there is no potential for damage to the existing structure underneath. Even so, sometimes, the roots of some plants can reach the underlay and cause leaks that might show up as bubbles or dark stains in the ceiling. Because the installation is usually complicated, it can be hard to trace the source and expensive to fix. One way to reduce the chances of this is to arrange yearly inspections.
4. Requires a lot of maintenance
Like any garden, green roofs also need attention. Intensive green roofs require regular application of fertilizers and weeding to ensure it thrives and remains free from threats like pests. If you are a hands-on homeowner with experience in gardening, this can be a fun hobby. But if you’re somebody who doesn’t have a lot of time on their hands, you will have to fish out a little extra to hire maintenance services to keep your building safe and stable. However, extensive green roofs require almost zero maintenance.
5. Limited plant selection
An extensive green roof, which is the most popular choice of the two types, can only support a few plants with shallow root systems, like grasses, mosses, lichens, and sedums. These aren’t very strong or attractive and can have trouble thriving if it’s very windy.
All the above points can help you make a fully informed decision to see if getting a green roof is something you should do. Personally, for you, if the potential drawbacks don’t outweigh the several benefits you can get out of it, then, by all means, you can get one installed on your existing roof.