Benjamin Hall Design crafts masonry accessory dwelling unit in Arizona

The Moon Valley Residence is a 1,756-square-foot accessory dwelling unit (ADU) in Phoenix, Arizona. It was designed by Benjamin Hall Design and completed in 2025.

The ADU is attached to a 1970s suburban house within a golf community overlooking Lookout Mountain. The project uses a concrete masonry unit (CMU) finish to create a bold, tactile material language that contrasts with the main home.

The design arranges four rectilinear volumes at varying elevations to carve views and modulate light. This approach delivers a sequence of compressed and expanded interior spaces while addressing multi-generational living needs and aging-in-place requirements.

Material-Driven Spatial Strategy in Moon Valley ADU

The project focuses on materiality and site response, using a continuous CMU finish as both exterior skin and interior surface. This choice creates a cohesive tactile quality and connects the dwelling to a desert vernacular.

The distinct elevations and volumes guide a clear spatial journey from the street to a private patio. The arrangement of volumes shapes the occupants’ experience as they move through the ADU.

Volumetric Organization, Elevations, and Privacy

A curved wall acts as a privacy screen for the cul-de-sac and defines the ADU’s intimate thresholds. An interstitial glazed volume connects the living and sleeping zones, allowing visual continuity while preserving separation where needed.

The wedge-shaped dining space links to the main house. A living room and kitchen oriented toward Lookout Mountain frame the desert views.

The sleeping quarters include a guest suite and a primary suite that opens to a private patio. This flexible arrangement can serve aging relatives or nearby family members while maintaining independence.

Materiality, Desert Context, and Sustainability

The design is influenced by the designer’s childhood travels through the Southwest and visits to Montezuma Castle. The Moon Valley ADU reduces typical single-family volume density and uses strategies to mitigate desert heat and glare.

The unbroken CMU surface creates a robust, low-maintenance envelope that withstands the region’s climate. It also provides a texturally rich interior.

This material-forward approach informs both performance and aesthetics in a compact, site-responsive plan.

Structural and Utility Strategies

To accommodate the continuous CMU finish, the design uses self-supporting masonry ceilings. This approach minimizes added framing that would break up the material language.

All utilities are integrated into built-in millwork. This is a practical solution because it allows for clean, uninterrupted CMU surfaces.

The project was delivered by Rare Form Builders. Structurology served as the structural engineer, and photography was by Logan Havens.

Key design features

• CMU exterior and interior finish creates a continuous, tactile material language across the ADU.
• Four rectilinear volumes set at varying elevations create a deliberate sequence of spaces.
• A curved wall provides privacy from the cul-de-sac and shapes the entry sequence.
• An interstitial glazed volume links living and sleeping zones for visual connection.
• Wedge-shaped dining space connects to the main house and expands dining opportunities.
• Living room and kitchen are oriented to Lookout Mountain to optimize views and daylight.
• Primary and guest suites open to private patios for outdoor-indoor living.
• Self-supporting masonry ceilings preserve uninterrupted CMU surfaces.
• All services are integrated into built-in millwork due to CMU constraints.
• The design supports multi-generational living and aging-in-place while maintaining family connectivity.
• Desert-appropriate strategies address heat, light, and material performance.
• Photographed by Logan Havens, with structural input from Structurology and construction by Rare Form Builders.

Moon Valley Residence reflects a Phoenix trend toward material-driven, site-responsive, small-scale architecture. The project demonstrates how CMU can be used for both beauty and durability while maintaining a strong connection to the desert landscape.

 
Here is the source article for this story: Benjamin Hall Design uses masonry walls for Arizona accessory dwelling