Green roofs aren’t just for far-sighted developers and bureaucrats. Homeowners and their dogs can enjoy them, too. Yep, dogs. Durham’s possibly first green roof is on a dog house. Although Lucy, a black Lab, doesn’t seem to care about her roof one way or the other, her owners now have one more place to garden, and it’s a way more people can learn about green building.

Skill level: basic carpentry.

Ingredients for a 4′ x 4′ doghouse:

  • Enough 6-inch wide pressure-treated (PT) lumber to make one “sandbox” on a flat roof (16 feet) or two sandboxes on a pitched roof (20 feet). (see photo)
  • Galvanized screws and PT scrap wood to stiffen the edge of the roof.
  • Weed block fabric and rubber pond liner, about 20 sq. feet. each
  • Saw, hammer, drill, tape measure, stapler, scissors, clamps, etc.
  • Peat moss, sand, Perma-Till in a 1:1:6 ratio, handful of lime and rock phosphate. Enough to make a 4-inch deep bed or 5 cu. feet.
  • At least 16 sedum, sempervivum and ice plants. Use more for faster coverage.
  • How to make it:

    1) Enclose the roof with a “sandbox” of 6-inch planks. May need to clamp and screw wood scraps under the edge of the roof to make it sturdy enough.

    2) Make the box an inch wider at its bottom edge so water can drain out. Staple pond liner to the bottom and sides of the box. Cut a slit at the bottom edge. Lay down weedblock fabric to protect the liner and staple the top edge to the inside walls as well, but don’t slit the bottom of the fabric–it’s there to keep the soil from pouring out the drainage slit with the rainwater.

    3) Measure the dimensions of your box to see how much soil mix is needed. “Soil” mix for a green roof is actually soilless–otherwise it weighs too much. Mix peat moss, sand, lime, rock phosphate and Perma-Till–a pricey, lightweight gravel that holds lots of air, water and nutrients–in a wheelbarrow. Dampen with water and spread it into the box, nearly level with the top edge.

    4) Install plants and finish with a thin mulch layer of Perma-Till. Water and weed as needed–probably not very often. Finally, invite friends over and see if you can start a trend.