Homes have been built with green roofs for hundreds of years; however, in Quebec, we are still reluctant to install them on hour homes and buildings. And yet, they have so much to offer: they help us save money, are environmentally friendly and relieve stress!
On the Régie du bâtiment’s (RBQ) governmental website (www.rbq.gouv.qc.ca), you will find a guide containing all the regulatory details pertaining to living roofs. For example, it cannot be more than 46 metres from the ground or its vegetation cannot exceed 1,200 millimetres at maturity. Most of the criteria is not limiting. The rub? A roof with an incline of more than 17% cannot be greened. This is why they are most often seen on apartment buildings and old houses with low-pitched roofs.
First: What Is a Green Roof?
A green roof is a type of roofing that contains growing vegetation (plants, flowers, vegetables…). It is comprised of a watertight membrane base sheet, a growing medium (i.e., the soil) and a drainage system. Even though many believe that these roofs came about during the 1990s environmental movement, it is an ancient idea. Buoyed by the experience, technology has made green roofs highly efficient.
Health Benefits
It is mostly in urban areas that homeowners are experimenting with these environmentally friendly roofs. So what are the health benefits? The plants, of course, improve air quality, but also reduce the house’s temperature since it protects it from the sun’s rays. Today, we are well aware that certain persons, especially babies and the elderly, are particularly at risk during heat waves. When it comes to mental health, plants calm us and reduce stress. It is equally possible to grow vegetables on the roof … and what could be better for the body than these vitamin-rich foods?
Is It a Good Investment?
A green roof could increase your home’s value. Many buyers are, in fact, on the lookout for them. The savings are real! Although living roofs are relatively expensive to install (between $10 and $120 per square foot), there is a rapid return on the investment. For example, you will save on heating and cooling. In the summer, the average temperature inside will be 27% lower than outside, while in winter, the heat will remain inside the home. Moreover, a green roof will extend the roofing and membrane’s lifespan as they are protected from UV rays. This is not financially insignificant! And how could we not mention the lower grocery bills thanks to homegrown herbs and vegetables?
Eco-Friendly
It is their eco-friendliness that often attracts users. We know that plants convert carbon dioxide into oxygen. A building’s green roof can on average remove 40 pounds of pollutants from the air per year! That is the annual equivalent of 15 cars. In the city, they are more than welcome as they diminish the heat island effect, i.e., localized temperature increases compared to rural areas. Green roofs also reduce surface runoff by absorbing water, reducing the risk of flooding and sewer contamination. It is likewise possible to recycle rain water to direct it onto to roof. The LEED green building rating system includes green roofs among its criteria.
Sound Proofing and Fire
Another, lesser-known, advantage of living roofs is their sound proofing abilities. Indeed, the medium blocks low frequencies while the plants stop the higher ones. The result? Residents are less exposed to outside noises like planes or music from neighbouring houses. On average, five inches of substrate will reduce sound by up to 40 decibels. Furthermore, in the event of a fire, a green roof will delay the flames reaching the roof (or from the roof to the building).
The Cons
But beware! Life is not always rosy in the land of green roofs! Insurance companies sometime require that the roof’s construction be validated by an architect or an engineer before insuring you, which can be expensive. Also, installing an access path to the roof (necessary as the rooftop plants must be looked after!) can be a limiting factor regarding space and budget. Finally, the watertight membrane will last 30 to 50 years, which means that the entire living roof will have to be removed in order to replace it.
There are many companies that will install your green roof for you, but if you’re handy, you can create your own. It is important, however, to do your homework to avoid the whole thing turning into a nightmare! You really must be mindful of the fact that the roof can only support a maximum amount of weight. And don’t forget water resistance. Living roofs are no more likely to leak than conventional roofs. What is important is that the “real” roof be in good condition and watertight.
So, has RE/MAX inspired you to embark on this adventure?