CAMANO ISLAND, Wash. — So there’s this slope. It’s exceedingly steep. Every once in a while, it sends down an uninvited little mudslide. That’s just not safe for your typical building techniques, says the official geotechnical study: You’re going to need a retaining wall. Tall. Long as the lot.

Except there’s this access issue. The building site sits on a remote (and particularly charming) beach on the west side of Camano Island. There is no road in. Residents park in a communal lot and hoof it down a bulkhead path, right outside neighbors’ windows, to their beachfront homes. Best of luck getting heavy equipment and concrete trucks down there.

But there’s this family. Dale Schwarzmiller and Sally Isaiou (plus two out-of-the-nest children in their 20s), whose other home is a 650-square-foot condo in Seattle’s Belltown neighborhood (“like your own hotel room,” Isaiou says). The Camano Island site they inherited, and its original little cabin, had been in the Schwarzmiller family for three generations. Schwarzmiller’s grandfather and relatives bought more lots, and today, his sisters, aunt and cousins all own homes along the same secluded stretch of beach. Abandoning family-at-this-beach tradition was about as likely as barreling down that skinny path in a wide-load excavator.

Happily, there were options. Dan Nelson of Designs Northwest Architects devises options.

What if they built the home on a steel-frame structure above the ground? On low-profile columns? So those pushy little surface slides would slip right underneath the house? And to hold the house stable, the foundation system could be tied together with deep, wide concrete-grade beams?

Well. That could work.

Did it ever.

So here’s the Saratoga Hill House: a super-engineered, 1,900-square-foot modern marvel (low-maintenance, affordably energy-efficient, clean lines, natural woods, simplicity, ease, light for miles) that stunningly responds to that one particularly steep challenge — and then some:

— Nelson had to work with a 50- to 55-foot envelope depth, shoreline requirements, bulkhead setbacks and smelt-spawning habitat rules. “There are only certain windows of the year to actually build on the beach,” Nelson says. “And since there’s no access by car, we could only drive on the beach during permitted times.” (Building materials were hauled up in a special cart crafted by contractor Mike Waite of Waite Construction, Inc.)

— To keep those supportive steel columns from the drainfield area, and from cutting into the toe of the slope, the northern end of the house is cantilevered above grade. (Bonus: room for a fern garden underneath, as Isaiou is a sales representative for a wholesale nursery and brings home “rescue” plants. “She’s the plant-whisperer,” says Schwarzmiller, who’s in management at a Seattle-based seafood-processing company.)

— Because the site is so tight, even more growing space, in the form of a rooftop garden terrace, lives on the upper level.

— By design, there’s no actual habitable space on the stilted lower level — just the mechanical room (power and utilities posed their own technical issues, Nelson says), plenty of beach/boat storage and expectation-setting stairs up to the entry.

— The east side of the home faces smack into that slippery slope, so more-opaque walls with limited narrow windows give only the best selective views of vegetation.

— To withstand sometimes-harsh coastal weather, the home is clad in metal siding. “We wanted surfaces that could take the beach and living, and that we would not have to paint,” Isaiou says.

Taking in the marine-themed home, soaking up all that light, gazing at Saratoga Passage through all those floor-to-ceiling windows (paddling ducks and elegant blue heron entertain regularly, and the occasional whale sighting triggers a “cousin phone network” up and down the beach), it’s clear the design works brilliantly with the site.

But here’s the thing: It’s not clear at all just how many site hurdles/hillsides that design overcame.

“As we discover limitations, part of our job is to break the news and explain: ‘By the way, we have to build your house on a steel frame,’ ” Nelson says. “It’s like everything you try to design — structures to solve problems. The more challenging, the more interesting architecture evolving out of the restraints.”