In cities everywhere, thoughtful design and construction rise up to combat seemingly inconsequential spaces, like this former weedy hillside in San Francisco. The owners recognized its potential, and after renovating their three-story house, they asked San Anselmo, Calif.–based Blasen Landscape Architecture to turn the steep backyard into a play space for their twin daughters. To complicate matters, a city-owned concrete retaining wall abutted the southern side yard next to a sidewalk. “San Francisco has quite a few building codes,” says principal Eric Blasen. “We had to take the wall higher, and we didn’t want to re-terrace that part of the yard.”

The design team created a private backyard garden that is inviting for rough-and-tumble kids to play, but orderly enough for adults to appreciate. What’s more, its crisp lines look good from above—another client requirement, since much of the outdoor grown-up activity takes place on the balcony and roof deck.

To meet the municipal requirements on the southern edge, Blasen inserted a new concrete wall about 18 inches away from the existing one so as not to put pressure on it. Nine steel piers were drilled 20 feet deep to support the new 44-foot-long wall in poor soils. Topped by a stepped fence and green hedge, the wall frames a tiered green canvas and clean concrete forms, inspired, Blasen says, by Japanese architect Tadao Ando’s minimalist approach to concrete. At the top is a cantilevered concrete bench where adults can sit to watch the children at play. Below is the sloped lawn with a climbing rope, concrete slide, and concrete steps that descend to a sand pit and flat lawn where the kids can pitch a tent. From there, a gate opens to steps leading to a lower mulched area containing an herb garden and storage.

“The slide idea came from a couple of neighborhoods in San Francisco that have big concrete slides, and kids would get a piece of cardboard and slide all the way down,” Blasen says. “This one is steel troweled very smoothly. We put recycled rubber at the bottom to make it safe, and so the grass there wouldn’t become a mud pit.”

Small details go a long way on tiny urban plots. Blasen placed a light strip in a recessed niche along the slide to illuminate the steps at night. The concrete forms are integrally colored to complement the house’s stucco cladding, and metalwork on the fence and gate ties into the railings on the house’s upper decks.

And about those upper decks: the key to designing for a bird’s-eye view is about movement, Blasen says. “We had the angle of the street to contend with, but felt strongly that all the rectilinear spaces should come off the house and let the angle do its thing. One green strip moves past another green strip and folds down the hillside.” No doubt the moving and folding feels right to the children, too.

Project Credits:

Project: Urban Play Yard, San Francisco 
Landscape Architect: Blasen Landscape Architecture, San Anselmo, Calif. 
Builder: Creative Spaces, San Francisco 
Architect: Gemmil Design, San Francisco 
Interior Designer: Mark Cunningham Design, New York 


Stone Garden Sculpture: Gallery Japonesque 
Roof Deck Furniture: March