A New Complex of Micro Flats in Arizona Invites Nature Inside

Located in the heart of downtown Phoenix, the blocky structure is perforated by succulent-filled atriums and skylights that look up to desert stars.

Nestled into the Triangle Neighborhood of downtown Phoenix is a new apartment complex that takes on the challenge of dispelling incorrect notions of city living. Made by Benjamin Hall Design in collaboration with 180 Degrees Design + Build, White Stone Flats is made up of four "micro flats" contained in two identical volumes—and all four flats sit in a footprint of just 600 square feet. "White Stone Flats is a true example that being connected to the outdoors doesn’t need to be compromised by high-density, micro housing," says designer Benjamin Hall.

"The ‘sugar cube’ like volumes of the complex allows the architecture to frame the historic home to the north and the seamless mirrored glass windows reflect the surrounding context onto the building facade," says designer Benjamin Hall. "It's sort of acting like a canvas for the context." 

The exterior landscaping is designed using succulents and desert plants to minimize the water requirements. Inside the complex, mature Palo Verde and Mesquite trees provide shade canopies over the walkways.

White Stone Flats sits in an infill lot that remained empty for two decades, until it was purchased by Hall. "Our goal was to design and develop architecture that could withstand the harsh desert climate and hopefully stand the test of time," he reveals. "To do so, the project needed to be financially sustainable, which in this case meant a minimum of four units. This would allow us to generate enough income to reduce the possibility of being torn down relatively soon."

The Triangle Neighborhood was originally developed with temporary housing for rail workers in the early 1900's.  

The site is located at an intersection within the Triangle Neighborhood, which was developed as temporary housing for rail workers in the early 1900's. "Walking around the neighborhood, you can feel the effects of gentrification moving in, but also a sense of its prior history," says Hall. "At 2:30pm every day, the ice cream truck rolls around and at 3:30pm the horn of the Mexican candy push cart rolls through. It's charming."

"The modern complex humbly matches the height of the neighboring gabled roof house to the north," says Hall. "The architecture tries not to compete with the historic brick construction of the early 1900's homes in the neighborhood. Instead, it finds joy in being a simple, modern version of the durable white concrete block construction, using today's contemporary building techniques." 

With easy access to the University of Arizona and Arizona State University in downtown Phoenix, the complex was originally developed for young couples or roommates who might want to split rent to make living costs more affordable. Interestingly, once they were built, the flats also attracted newly retired couples who wanted to downsize yet still be centrally located.

The building is primarily constructed from custom concrete masonry units (CMU blocks). Each CMU block has a foam-filled interior core to provide an R20 insulation value and the white color helps reflect the harsh desert heat off of the building. "The feeling of the pathway between the two built forms is reminiscent of standing in a Northern Arizona slot canyon," says Hall.  

"The idea of bringing high-end design that's hyper-focused on detailing to multi-family housing, generally has not been embraced professionally," says Hall. With this approach in mind, the architecture was conceived as a simple box and the budget was spent on "fine tuning the little things".

Hall was part of the day-to-day build, which led to subtle refinements of the design throughout. "One day, I saw the beautiful pattern left by the crew using a concrete screed—a tool used to temporarily stamp on wet concrete to drive the moisture to the top. The morning light hit that surface in a way that inspired me to stop the crew and leave this texture as the final product," he says. "In a million years I would never envision that texture in a way that I could accurately annotate in a drawing." 

Residents enter the complex through a steel gate and are greeted by the sound of a fountain, which drowns out the city sounds. The apartments are located through a complex pathway between the two building volumes. "The architecture creates a self-shaded pathway—like the old barrio neighborhoods of Tucson, Arizona—through the composition of the complex," says Hall. "You meander till you are welcomed by simple vertical ipe wood gates, with a simple steel letter, denoting a unit coordinate, north, south, east or west."

Each unit is designed around the two-story slot atrium—which functions like an interior garden or courtyard. 

Behind each timber entry gate is a private two-story "slot" atrium, which opens up to the desert sky. The apartment is then entered through a glass door in a glazed wall. "The idea was that every space should have access to an open-air atrium and abundant desert light, while the hard-shell exterior does all the hard work of shielding the sun," says Hall.

Each apartment has access to a private two-story "slot" atrium. "It's like stepping under a giant skylight," says Hall. "Eventually, the creeping fig vines will scale the full height of the space." The narrow atrium also provides separation between the apartments. "Nature and access to unobstructed daylight without compromising privacy is paramount in this project," says Hall. 

The glazed entrance door leads directly into the bright, white open-plan living, dining and kitchen space on the ground floor. 

Kitchen appliances, including the oven and fridge, are built into the timber joinery beneath the stair. The door to the bathroom is also concealed behind this cabinetry, keeping the space visually uncluttered.

The ground floor features an open-plan living/dining/kitchen space, with a "secret" door to the bathroom/laundry room hidden behind one of the white birch plywood cabinets in the kitchen. The glass shower opens out to the private atrium.

The kitchen has views into the atrium, and the cooktop hood is tucked flush into the ceiling plane leaving the view unobstructed.  

The kitchen countertop extends the length of the space becoming the dinning surface, negating the need for a dining table in such a small living space. 

Thoughtful details, such as this storage nook built into the wall at the end of the kitchen bench, help to condense the essentials into a small footprint.  

The small living space is adjacent to the stair, which conceals a number of utilities beneath it. Concrete floors give the space a refined industrial edge. 

"The glass shower is operable to your private atrium providing you the sensation of showering outdoors in your small but protected environment," says Hall. The water-resistant coating on the interior-facing blocks allowed for an exposed shower wall without the need for tile surface treatment.  

Upstairs, there are two identically sized bedrooms with floor-to-ceiling frameless doors and authentic French oak floors. "The combination of frameless doors and windows and the full height wall-to-wall, high-gloss white closet doors help bounce the ambient light in a way that makes the modest dimensions of the space feel expansive," says Hall.

The stair treads have been cleverly constructed to save space. "We knew that the depth of typical construction would impede the head clearance of the user while in the kitchen," says Hall. "Instead of using stringers, we engineered the steel treads to be self supporting folded plate steel to avoid having any exposed structural elements on the underside."

The entire width of each bedroom is lined with floor to ceiling closets to maximize storage in the small space, and bedside nooks have been recessed into the block wall in the bedrooms to create storage within the architecture itself. 

The upper level features two bedrooms. Some tenants have converted one bedroom into a light-filled study. 

The most notable material used—and the one from which the complex takes its name—is the custom white concrete masonry unit (CMU blocks). Although the construction appears simple, it’s actually a matrix of 42 different block types with two to three subtle surface treatments on each block. The outside face, for example, is honed once, while the inside face is honed twice with a high-gloss, water resistant coating.

The purpose of the high-gloss-coated surface facing the interior was to optimize for the most ambient light to bounce into the depth of the space. 

"The white concrete blocks were the most costly part of the build, but it's money well spent because they serve so many functions," reveals Hall. "They reflect heat off the walls, are durable, and it’s the final finish of both the inside and outside. It doesn't require paint and it ultimately lowers the maintenance costs for the longevity of the building."

Each unit is identical, but is oriented in a different direction—one gets south light, north light, east light, and west light.  

The resulting micro-flats are a study in crafting high-density homes in a city environment, while still remaining connected to nature—something Hall points out is more important than ever these days. "It’s especially unique to leave your doors and windows open all night to the atrium and feel as if you are living outside without any hesitation walking around in the nude," he says. "We’ve also had tenants comment on how lovely it is to lay in bed at night and rest your head on a pillow and watch shooting stars through the top of the atrium." 

Site plan of White Stone Flats by Benjamin Hall Design 

Ground floor plan of White Stone Flats by Benjamin Hall Design 

Second floor plan of White Stone Flats by Benjamin Hall Design 

Sections of White Stone Flats by Benjamin Hall Design 

Elevations of White Stone Flats by Benjamin Hall Design


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