The National Parks Service defines a Green Roof as a layer of vegetation planted over a waterproofing system that is installed on top of a flat or slightly–sloped roof. Green roofs are also known as vegetative or eco-roofs.
This week’s video features a green roof project we’re doing for Recovery Bike Shop in Northeast Minneapolis. Recovery Bike Shop wanted to do their part in creating a sustainable, efficient environment in the city. They needed a new roof, but also know that the roof is valuable real estate that is soaking up the sun without any return. They decided to go with a green roof.
Benefits of a Green Roof
Installing a green roof can drastically improve the quality and lifetime of your flat roof. If you own a commercial property and have or are installing a flat roof, taking that extra step to install a green roof can be the right move.
Some more benefits include;
- Preventing runoff
- Conserving energy
- Decreasing erosion around your foundation
- Providing habitat for wildlife
- Reducing noise and air pollution
- Preventing more heat distributed through the urban atmosphere
The Lifespan of a Green Roof
Green roofs are incredibly sustainable and longlasting. With proper installation and maintenance, a green roof can double or even triple the typical lifespan of a roof. Research shows countries like those in Europe who have been installing green roofs since the 1960s, have lasted between 30 and 50 years. They can also help with extending the lives of local wildlife by creating a safe, self-sustaining habitat, away from predators and human interference. The effect green roofs has on greenhouse effects is also major, in that it takes away an asphalt roof that is only going to absorb heat from the sun and add it to the dome effect around major cities.
An event occurs in big cities, that makes one area warmer than it’s surroundings, called Urban Heat Island. Materials in urban areas like concrete and asphalt on roads, buildings, and roofs heat up and that excessive heat remains trapped in that concentrated area. In fact, in cities where temperatures reach the 90s, it can heat some roofing materials to almost twice that temperature! Turf and green roofs can actually keep the temperature of your roof down well below the environmental temperature. Plants also naturally cool things during evaporation, which not only aids in limiting urban heat island effects but keeps the building cooler naturally vs. using air conditioning.
USGS.gov states that about 70% of all rainwater is re-absorbed into the atmosphere by evaporation, the other 30% makes its way to lakes and rivers by runoff, mostly in urban areas where it can quickly travel versus rural areas where it travels slowly on the ground. Green roofs help alleviate or almost eliminate rainwater runoff on commercial buildings and homes by allowing it to soak into the green roof layers, and give it time to evaporate before causing rapid runoff. Runoff is bad because it flows quickly, grabbing contaminants in the city and carrying it to streams, rivers, or lakes. It also puts incredible wear and tear on city sewer systems.
Lastly, more plants mean cleaner air. Green roofs can help put out more oxygen and cleaner air in the city setting. It helps create habitats for birds, butterflies, and insects that can rapidly decrease in urban landscapes from destructive construction and building in the city.
Extensive vs Intensive Roofs
There are essentially two different types of green roofs – extensive and intensive. Extensive roofs are more natural and wild, they kind of grow on their own. The intensive roofs are a more curated, manicured green roof, with plants and paths and more integral areas that can be used for entertaining.
- Light soil
- Low maintenance
- No need for irrigation or drainage system
- Suitable for large area roofs
- More natural
- Less diverse plant options
- Not good for any other recreational use
- Can be unattractive and unruly
- Deep soil
- More diverse habitat and plant options
- Great insulation
- Aesthetically pleasing
- Simulates a wildlife garden and habitat
- Can offer recreation, growing food, open space
- Requires more maintenance
- More weight on the roof
- More expensive
- More complex and uses more resources
The popularity of green roofs will continue to rise as people realize their amazing benefits that end up paying off financially and environmentally in the end. Save energy and promote environmental health with a green roof. Call us to learn more!