A retractable roof shades the dining area and creates privacy.

The key to getting it right with a rooftop terrace, as with so many things, is to simplify. Pare it down to the essentials: What, exactly, do you think you’ll do out there-serve dinner, look at the skyline, practice your putt, do yoga-and what will you need in order to make those activities happen?

For homeowners who had a long, slender rooftop space with their River North condo, Bill Mitchell, a designer for Chicago Specialty Gardens, distilled their needs and wishes down to a minimum, then whipped up a stunning space that is flexible, distinctive, and cleverly detailed.

Drama after dark: Willow twigs, a wooden frame, and uplighting make for a clever, inexpensive wall sculpture that hides a fence. Cushioned benches (opposite) are perfect for star-gazing.

Into a layout just 12 feet wide but 45 feet long, Mitchell tucked a dining area with a retractable roof, a fabulously inventive wall hanging, an inviting set of cushioned Western-cedar benches perfect for lounging after dinner, a kids’ play space, and a smart abstraction of a catwalk that leads from the condo to an overlook for viewing the city. The sections fit together in a sleek, modular way, allowing them to function either separately or together as one large, seamless space.

"They needed it to be flexible because they have kids and they entertain," Mitchell says."And they wanted it to match their interior aesthetic, which is clean and modern and a little Euro."

The dining area of the terrace is floored with landscape-quality marble squares laid on cedar decking supports, and ceilinged with a metal pergola whose blinds can be opened up for a view of the sky or closed to block out bright sun.

The dramatic effect of a nature-inspired wall hanging belies the somewhat pedestrian way it came into being: A six-foot fence that separates this private space from a common area used by all the building’s residents had to be reckoned with."They asked us for something they could look at instead of the fence," Mitchell says."We just wanted to push it into the background, so we put a foreground in front of it."

With no room to plant a vine, Mitchell created a kind of wall sculpture instead. He dismantled some standard, storebought willow fencing, rearranged the willow twigs in a looser grouping, and put them behind a carpenter-built frame. Add some uplighting from the floor level, and you’ve got a fantastic, easy piece of outdoor art."When it’s lighted up at night, the effect is like a fire," Mitchell says.

A long, narrow space that runs along the edge of the terrace acts as a catwalk leading from indoors to the spot with the best view-an open space behind the benches. The catwalk is covered with outdoor carpeting similar in color to the building’s concrete and has a waist-high steel railing along its outer edge."You want people to be able to get there, so we drew a straight line with the carpeting," Mitchell says. Guests don’t have to thread their way between benches and other obstructions-they can make a beeline to the main attraction.

Except for the carpeting, which will need to be replaced every three years or so, the rooftop deck is a distinctly low-maintenance space. Plant-wise, the only annuals are petunias and a few others in boxes hanging from the railing. The serviceberry trees and Swiss pines in the big planter boxes and the switch grass along the benches will potentially live ten years or more.

All three main planting elements provide seasonal visuals. The grass’s fall blooms stay and turn a winter beige. The serviceberries have romantic puffs of flowers in spring, bright orange leaves in fall, and delicate multiple trunks all winter. The pines, of course, stand out in winter, too. The homeowners look out on this space all year, Mitchell notes." So we put uplighting on the trees to give them something to enjoy."

Altogether, the elements add up to a terrific solution to the challenges presented by a skinny, sky-high urban terrace.

Photography: Linda Oyama Bryan