Taking green to new heights

Teresa Williams and David Leppanen's roof is alive. Last fall, the Bellingham couple installed a green roof, and now it's in full bloom.

Today, when they look out of their living-room window, they see saxifrage, flowering rosettes of houseleeks and eggplant-colored tulips.

Already popular in Europe for their environmental benefits and aesthetic pleasures, green roofs are becoming in-demand in the United States.

For Williams and Leppanen, the practical and philosophical bonuses of the garden over their heads had appeal.

"I hate the idea of paving over the Earth," says Williams, a prosecutor for the Lummi Nation tribe.

This, she says, is the opposite.

Gaining popularity

Resources


Greenroofs.com: www.greenroofs.com

Green Roofs for Healthy Cities: www.greenroofs.org

Green Roof Plants at Emory Knoll Farms: www.greenroofplants.com

Green Roof Project: www.hadj.net/green-roofs

The idea of a garden roof is nothing new — they go back to the hanging gardens of Babylon and centuries-old turf roofs of Viking settlements. In Europe, they're well established: An estimated 10 percent of all roofs in Germany are green.

But in the United States, they're just catching on.

Green roofs, eco-roofs or vegetated roofs, as they're called, are increasingly touted as a way to beautify concrete-bound urban areas, regulate global warming and spare rivers from stormwater contamination.

The couple — 1974 Western Washington University grads who returned to Bellingham in 2001 after two decades living in Alaska — wanted to expand their home with a shop. Williams didn't want to look out on a bare roof, so they decided on a green roof, something they hoped would be beautiful and functional.

Pricey project

A green roof can help regulate temperature and absorb stormwater, which runs off slowly instead of pouring down in buckets and overwhelming sewer systems.

"It's not cheap, but the expense is worth it," says Leppanen, a general contractor.

"You can't do this in a weekend with plastic bags and dirt and just hope for the best," says Williams.

High-quality materials are essential, because a poorly built green roof can cause structural damage to a home by compressing the roof or leaking. It will increase building costs 20 to 35 percent, Leppanen says. A project like their green roof might cost around $30,000, says Leppanen.

Because Leppanen did much of the work and design himself, their total cost was lower.

There's a potential to recoup some costs, because the vegetation can act like insulation.

"I would think that if it was over living space ... a green roof is going to give you more insulation and help keep it cooler in the summertime, and warmer in the wintertime," says Leppanen.

It's also beautiful. The 750-square-foot roof garden is the focal point of the whole house, says Williams.

Selecting plants

To build theirs, Williams and Leppanen consulted Patrick Carey, a Seattle-based expert on the topic.

He told them that a green roof must have three main elements to be successful: It can't leak, can't be too heavy and must sustain the greenery growing on it.

Because Leppanen was building the shop from scratch, he angled the roof to absorb the increased weight of soil and vegetation.

They used a rubber lining (much like a pond liner), a drainage mat and a soil layer (a mix of crushed lava rock, sand, composted soil and water retention granules). They needed plants that would tolerate drought conditions, require only 6 inches of soil and thrive in heavy exposure.

They covered the area with more than 500 flower bulbs, several flats of grasses and many varieties of sedum and saxifrage. After a rainy winter, their roof is in full bloom.

Steller's jays, finches, chickadees, squirrels and robins also have stopped by to admire it and search for seeds.

But the best part, says Williams, is morning coffee in the living room while looking out on the green patch.