It is hard to believe that it has been 10 years already for the green roof on my house, as of this past weekend. (I was on a train and couldn’t write this all out then.)  You can get a peek of the greenery from the front of my house (see left), but there are many more, better pictures below – because it’s the first thing I see out the window when I wake up.

It’s been completely, wonderfully worth the bit of extra money in cost up front, and is saving me money in the long-run, is helping the environment, is fighting the urban heat island effect, is thus helping my city, and it is fighting climate change.  Plus, I see life in it.  Not asphalt shingles.  Life as in greenery and flowers, bees and butterflies, funnel spiders, preying mantises, and baby squirrels playing.

So, thought about working your house (or office) truly into the ecosystem? Consider a green roof. Green roofs are literally roofs of soil planted with plants, traditionally plants that are selected are both drought and water tolerant so that little watering is required, but when it does rain, they absorb water fast and hold it, reducing flooding.

Many cities (Chicago, Washington DC, etc..), and countries (Britain, France) are providing incentives for them, because green roofs have a ton (pun intended) of impact on climate change and flooding. They so out-rate the traditional alternatives of asphalt shingles, or of tar and sometimes gravel for a flat roof. Only solar roofs come close in impact.  Thus they are often chosen nowadays for government and industry buildings: Government Building Green Roof Tracker (USA).

What all do green roofs do related to climate change and you?

Say on a residential roof? They:

• Reduce the urban heat island effect.
• Insulate your house amazingly well – soil is considered one of the best insulators out there.
• Hold back water during storms to prevent flooding (the plants and soil absorb the first rain, while the rest then runs off the roof.)
• Do not heat up storm water like asphalt roofs do – thus they do not kill plants and animals downstream.
• Provide flowers for pollinators, homes for trapdoor spiders, preying mantises, and more.
• Look better than asphalt roofs, thus helping you enjoy life more, giving you more energy for the climate fight.
• Last up to 60 years, so reduce the cost (and fumes) of the installation of asphalt roofs every 15 years.
• Provide cats with an lovely outdoor view, thus reducing time they bother you because they are bored.
• Oh, also, they *slow* the water rushing off a roof, thus slowing stormwater downstream and decreasing flooding.

This last is often the winning reason for cities to incentivize installation.

There are several layers to a green roof that make it work. The first is the waterproofing membrane that all roofers put down no matter what the roof type. But on top of that, instead of shingles, are a membrane protector, then root-blocking membranes, and then four inches of a light pumice rock/soil growing medium. This greenery and the soil will keep the heat from degrading the waterproofing membrane, which will make the roof last much longer.
These facts come from a blog series done by one of our senior editors for the Washington Post several years ago as she installed her green roof (pictured). The entire blog and the series of images showing each stage, can be reached through this last article.
https://www.washingtonpost.com/news/where-we-live/wp/2013/08/14/a-petworth-homeowners-green-roof-one-year-later/.

But here’s a picture gallery of the installation to give you an idea of how it works:

Tips for making a green roof work for you:

• You will need a structural engineer to come out and look at the roof of an existing structure, in order to ensure that it will support the weight. Often, they will need extra support.

• This is a job really for a special construction firm for a built-in green roof, unless you just put modular boxes of soil out on part of your roof. These modules are available for order, such as seen here: ‘https://www.greening-solution.com/green-roof-trays/. (We aren’t recommending this particular company, this is just for illustrative purposes. Also, carefully calculate the weight!)

• Some green roof designs are meant for larger plants, such as for rooftop farms and trees, and thus may have soil up to a meter deep. These types of roofs require super strong steel beams underneath. Low-lying plants, like sedums, succulents, and some herbs, many of which are great pollinator plants, can get away with four inches of a light soil, making a much more practical roof for homeowners.

• Look for plants specific to your locale, such as these plants for Colorado: https://sowgreen.co/news/plantsforagreenroof/.

• See what incentives your city provides for this. Some nonprofits sometimes are asked to manage programs like this, and a decent search on your city or county’s website should be able to find them – if they exist.

• Finally, green roofs, at least the type shown in the picture, often don’t require weeding once the sedums and other green roof plants have grown in. These roofs are meant to be accessible, yes, but low-maintenance, because people usually aren’t meant to be on most home roofs. But do try to have part of it at least in your view.

• After you install, invite neighbors over for a green roof open house! Show it off, and spread the word. Have a booth at the farmer’s market. You might even get props as a gift, as I did!

 

Check out our other information regarding Buildings and Climate Change:  Buildings.