SEATTLE—Michelle Lanker and her husband, Bill Bloxom, are great neighbours.

They live in a distinctively designed, floating home on Lake Union, where their fellow, water-top dwellers form “a very tight-knit community,” says Lanker. “A lot of these folks have been here for years.”

Bloxom included.

He once owned a turn-of-the-century floating home at the same slip. But while he was renting it out, a lit cigarette dropped below the deck and ignited a devastating fire.

The unfortunate neighbourhood aftermath: “The burnt crisp of a house had to sit here,” Lanker says. “The slip can’t be left open more than 30 days.”

The awesome neighbourhood aftermath: The couple considers the whole lake their community, so their new LEED Platinum-certified floating home is a contemporary dock-party addition of super-sustainable — and super-courteous — design.

Some of its environmental elements and approaches might sound familiar: maximum insulation/minimum air leakage; minimum maintenance/maximum durability; salvaged, recycled, rapidly renewable materials; low-E triple glazing; LED light fixtures; Energy Star appliances; water-efficient fixtures.

As well as building something admirable and inspiring, Lanker says: “We wanted to push the limits to what a houseboat could be.”

Take the standing-seam metal roof, for example, and its sleek waterslide of a curve (originally conceived by designer Gloria Andrade, before architect Michelle, of Lanker Design, jumped on board). Not only does it pair with panoramic clerestory windows, it also purposefully displays 5.32 kW of solar panels, and a vegetated roof system.

There are floating islands attached to the floating home: planters filled with wetland plants — most native to Lake Union. The islands, in various sizes, let the root systems extend into the water, creating fish habitat. “The roots are not only cleaning the water, but the recycled plastic material the plants are growing in is like a sponge in an aquarium: Microorganisms are living in it, also. Pretty cool, I have to say,” says Lanker.

It gets cooler. “Bill said, ‘I want an observatory for what these floating islands could do,’” she says. So, downstairs — yes, there’s a fully livable downstairs — “The concrete float of the home becomes an observation room for studying these floating islands through a large underwater window. We’re in 50-plus feet of water here. I see smallmouth bass more than anything else.”

Also cool, in a warming way: “A hydrothermal heating system, basically powered from the lake,” Lanker says. In addition to a series of tanks, a heat pump and a pump-flow centre, it involves a titanium plate suspended in the lake and a transfer fluid loop of glycol. “It’s so great. … Here we keep it at a set temperature, and it stays constant. For most of the year, what we get out of the lake is all we need for heat.”

And, devastating though it was, the fire did not take everything. Twenty-two old-growth cedar logs, some 24 feet long and three feet in diameter, all part of the home’s original float, were salvaged. “All the wood in the house is salvaged from those logs.” You can see it in the custom coffee table Michelle designed, in the living area’s centrepiece sculptural element, and in the upstairs master suite’s built-in bed frame.