Question

We want to add a green roof to our Virginia log cabin. Will pests and weeds be a problem?

Asked by John Duke, Richmond, VA

We are renovating a log cabin. Part of the building will have a flat extension that we want to use as a native Virginia sedum-planted green roof. The cabin is surrounded by large oaks and other trees, which attract a lot of squirrels. Do I need to be concerned about constantly weeding the roof of seedlings? Is the sedum going to be attractive to the squirrels?

Answer

John Messerschmidt

Answered by John Messerschmidt

New York, NY

Four Points Consulting Group

July 6, 2009

In the city, people claim a green roof will save energy, reduce the heat island effect, and prevent stormwater from overflowing the sewers.

A cabin in the woods doesn't have the second two problems, and I doubt there would be enough energy savings to justify the expense, so there is no real reason to install a green roof unless you want a real expensive squirrel feeder.

I don't know how much green roofs cost in your area, but people are paying $15 to $20 per sq. ft. for them in NYC. Then they have to irrigate them for two years until the plants are established.

Install a heavily insulated conventional roof instead

Rather than planting a green roof, I would install a conventional roof with plenty of insulation.

  • Use two inches of rigid foam on the roof deck, then spray the underside with expanding foam.
  • The most environmentally preferable roofing option is a standing-seam metal roof. They last 25-plus years, and have no petrochemicals as asphalt roofs do.

If you don't like the look of a stainless-steel roof on a log cabin, I wouldn't have a problem recommending a small, cabin-size asphalt roof—as long as you take advantage of the renovation and beef up the insulation in your walls, too.

  • Closed-cell spray foam or blown-in cellulose will make your cabin extremely energy efficient, and cozy in the winter.
  • I realize this is a lot of plastic for a cabin in the woods, but if you burn less carbon to heat the place than you otherwise would, maybe the earth will forgive you for using a few asphalt shingles and some plastic foam.

Supporting native plants

If your aim is to save water and encourage local biodiversity, there are other ways to achieve this.

  • Install a rainwater catchment barrel connected to drip irrigation so you don't have to water your yard as much.
  • Maybe you have a local nursery that can recommend native plants and flowers for landscaping.

If you dig up the invasives that are already there, chances are native plants will grow back naturally.

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