Concrete Cool in the Arizona Desert: The Moon Valley Residence

When it comes to architectural additions, the traditional backyard “granny flat” or guest house often leaves a lot to be desired in the design department. However, we see a lot of phenomenal residential projects here at The Coolector, and every once in a while, a studio completely rewrites the rulebook.

Enter the Moon Valley Residence. Designed by the visionary team at local Phoenix studio Benjamin Hall Design, this jaw-dropping 1,756-square-foot Accessory Dwelling Unit (ADU) is a masterclass in multi-generational living.

Attached to an existing 1970s suburban home in a tranquil golf community, the newly completed 2025 project intentionally and brilliantly contrasts its older counterpart, creating a distinctly modern desert sanctuary that looks out toward the rugged beauty of Lookout Mountain.

A Masterclass in Exposed Masonry

Instead of trying to mimic the dated 1970s architecture of the main property, Benjamin Hall Design opted for a bold, unapologetic approach.

The entire structure is constructed using grey concrete masonry units (CMU), which serve as both the rugged exterior facade and the highly refined interior finish.

This heavy, tactile material choice wasn’t just about achieving a striking, minimalist aesthetic—it draws direct, heartfelt inspiration from studio founder Benjamin Hall’s childhood memories of travelling through the American Southwest with his father.

To maintain a vital sense of seclusion from the neighbourhood cul-de-sac, a sweeping, beautifully curved concrete wall shields the entrance. This ensures that the ADU remains a highly private retreat, despite sharing a practical access door with the main house.

The way the harsh Arizona sunlight plays across the raw concrete textures throughout the day gives the home an ever-changing, dynamic energy.

Interlocking Volumes and Curated Views

Set respectfully lower than the roofline of the original house, the Moon Valley Residence is cleverly composed of four distinct, interlocking volumes. Each section has been meticulously carved out with strategic apertures to perfectly frame the surrounding desert landscape.

The architectural journey begins in the first volume, which serves as the connective tissue to the main home via a striking wedge-shaped dining space.

Here, massive sliding glass doors open up completely to a private patio, effortlessly blurring the lines between indoor and outdoor living.

This flow continues seamlessly into the second volume, which houses a sleek kitchen and a living room that boasts uninterrupted, carefully curated views of Lookout Mountain.

Moving deeper into the footprint, a beautifully glazed interstitial volume acts as a luminous, light-filled corridor, guiding you toward the highly private sleeping quarters.

This final, fourth volume contains a comfortable guest suite alongside a luxurious primary suite, complete with its own secluded patio space for morning coffees in the desert air.

Engineered for the Future

Beyond its undeniable visual appeal, the Moon Valley Residence is fundamentally designed with a beautiful, functional purpose: to allow a retired couple to age in place comfortably.

It provides them with total independence and bespoke luxury, while keeping them physically connected to their children and grandchildren residing in the main house next door.

From an engineering standpoint, the home is just as impressive as its aesthetic. Because the architects committed to using continuous CMU blocks—even engineering strategic spans to allow for incredible self-supporting masonry ceilings—traditional drywall cavities were completely eliminated.

As a result, all of the home’s vital utilities, wiring, and plumbing had to be ingeniously concealed within bespoke, built-in millwork.

It is this level of meticulous problem-solving and uncompromising design that makes the Moon Valley Residence an absolute standout in the world of modern architecture.

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