Going Green on Top: Row Houses and Green Roofs

You’d have to live under a rock, and maybe not even there, to not know something about the state of the environment. Everywhere you turn, government and celebrity representatives are urging you to make even a small change to balance out the resources you consume every day.

Container gardens in front of a row house in Philadelphia.
Container gardens in front of a row house in Philadelphia.

I have been fortunate enough to live in two cities that place a very high emphasis on reducing waste and emissions. New York City recycles militantly, ticketing you if you mix your glass with your leftovers. Every time I visit, I see more and more hybrid cabs. When I lived there, I hardly ever drove. We took the subway or walked.

As a resident of Philadelphia, I walk even more since I no longer have to take a subway to work and I am recycling more than ever. We’re also on one heck of a budget so we don’t buy anything we don’t absolutely need. Less consuming equals less waste. Additionally, the new heating system we just purchased was the top of the line in efficiency and we try to keep it as cold or hot as we can stand, depending.

I was reading the April 16th issue of Newsweek which was all about the environment and I scanned over an article about green roofs. Since I happen to now have a roof, I read on.

Having a green roof can lower the temperature of your roof in the summer from over 120 degrees to closer to 80. This might not seem like a lot but if you have a bedroom in your attic, 80 degrees is practically arctic. A green roof cools your entire house and keeping the house cooler in the summer means less air conditioning. As an added bonus, the green roof also insulates the home in the winter and keeps the warm air in.

I went to Greenroofs.com to do a little research. Their FAQ page is very informative. I’ve summarized a few key points:

  • What is a green roof?
    In the most simplest definition, a green roof is a roof that has growing things on it. Your plants replace the normal things which go on a roof such as shingles or tiles. Most green roofs have a waterproof lining layer, drainage, something to grow the plants in and the plants themselves. Typically the entire roof is covered. There are two types, extensive which is low maintenance ground cover and intensive which are more traditional gardens with a variety of plants. In both cases the plants get planted into dirt on the roof, not merely planted in pots standing on the roof.
  • Do I need a flat roof?
    Although intensive green roofs need to be relatively level, extensive green roofs can be grown on slopes up to 30 degrees and more if structural enhancements are made.
  • Will my roof cave in?
    Actually the extensive roofs don’t weigh too much, about 10 to 50 pounds per square foot. Intensive are a little more involved and can weigh upwards of 120 pounds per square foot. Neither will collapse a roof in good condition.
  • How do I care for my green roof?
    Everyone should check their roof yearly for stability. When you have a green roof, you also need to check to make sure the plants haven’t migrated somewhere unwanted. You also have to make sure the root aren’t interfering with any of the underlying structure. The plants also need to be cared for just like any other plant. They’ll need to be watered and you have to watch for any stress because living on a roof, they will be subjected to harsh winds and weather.
  • Setting up your green roof.
    Make sure the under layer is made out of something the root cannot penetrate like polyethylene. You have to use special dirt which is lightweight, drains well, and yet retains rain water. A typical mix is 1/3 clean topsoil, 1/3 compost, 1/3 perlite or other inorganic material.

There is a lot more information at the web site that covers what kind of plants work well and more benefits to having a green roof. A green roof probably isn’t for a novice gardener. It’s suggested that the typical homeowner should have a professional install the garden as well as an engineer come to inspect the home prior to installation. But the expense and effort is well worth the investment.

Even if you can’t commit to a full green roof, you can still keep as big a garden as possible and bring a little green into the city.

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