Two great ideas don’t always play well together. That’s certainly true in the urban design realm, at least as a practical matter. Building on an infill lot avoids waste and the fragmentation caused by scattering houses into the countryside. It leads to a compact city with a clear identity and pedestrian-friendly streets. And a beautiful dwelling inspires everything around it. But can the twain meet on a tight trapezoidal plot?

Project Credits:

Builder: McCoubrey/Overholser, Philadelphia; Architect: Qb3 Design, Philadelphia; Living space: 3,000 square feet; Site: 0.02 acres; Construction cost: $400 per square foot; Photographer: Todd Mason/Halkin Photography. / Resources: Bathroom plumbing fixtures: Hastings, Kohler; Bathroom plumbing fittings: Duravit, Hansgrohe; Bathroom cabinets: Broan, James Van Etten; Brick/masonry products: Endicott; Countertops: Caesarstone; Dishwasher and range: Bosch; Entry door, garage door, and exterior siding: James Van Etten; Garbage disposal: Waste King; Hardware: Schlage; Kitchen cabinets: James Van Etten; Kitchen plumbing fittings and fixtures: Blanco; Lighting fixtures: Bega, Contrast Lighting; Oven: Jenn-Air; Paints/stains: Benjamin Moore; Patio doors and windows: Weather Shield; Refrigerator: GE Monogram; Skylights/roof windows: Velux.

They can, and do, thanks to the collaboration by builder Charlie Overholser, of McCoubrey/Overholser, and Qb3 Design partners Stephen Mileto, Kevin Angstadt, and Patrycja Doniewski. Located in the eclectic Northern Liberties section of Philadelphia, this house adds a bright domestic presence to an awkward site while strengthening the neighborhood’s ties to its industrial past. But its forward-thinking stance belies the often extraordinary challenges of building on a remnant lot.

Curve Wall

A reinterpretation of the old pharmacy building across the street, the Split Level House’s arcing façade makes sense of the irregular street grid. And the glazed three-story entry slot frames views across layers of space: from inside to outside and back inside again.

The cantilevered curve contains a structural steel radius tied to a series of point loads on round lolly columns. Its metal stud framing was covered in plywood sheathing and then sprayed with a waterproof membrane. “The radius was gentle enough that we could bend the plywood,” says builder Charlie Overholser. To lay the Flemish bond-pattern brick, masons strung lines from top to bottom, point to point, every foot or so to maintain the radius. “It’s standard brick, not curved,” he says. “We were within an acceptable limit where it didn’t look faceted.”

Northern Liberties has a colorful, if hardscrabble, past. Until the middle of the last century, it was a manufacturing hub populated by German and Irish immigrants who lived in tiny row houses near the tanneries, factories, and foundries where they worked. Blight claimed it in the 1970s as those jobs crumbled away, but over the past 10 years, redevelopment and the influx of artists and professionals has led to a renaissance. Responding to that history, Qb3 chose basic exterior materials—brick, wood, and concrete. Design cues came from a series of bullnose corner buildings on the street, including an inn that stood on this parcel until about 30 years ago.

The home’s bullnose brick wraps the front corner, cantilevering over a deeply recessed entryway. But the unusual split-floor layout came from the owner’s request for a garage, and the need to elevate the front door to create some distance from the street. “It immediately started setting up this series of splits through the small, irregularly shaped site,” Mileto says.

Six exposed pipe columns skewer the two halves of the building together, creating point loads for staggered platforms that lead upward through the house and expand the space horizontally as well as vertically. “You’re always looking into the floor below and above, or out on the street, or straight through the building,” Mileto says. The seven levels culminate in a master suite with views of an eye-level roof garden and brick parapet.

This complicated scheme called for steel framing. The cantilevered radius required it, and with only a sidewalk staging area, the structure had to go up quickly. Of course, the budget affected the playbook and added new technical challenges. To save money by mobilizing the steel framing crew just once, the structure was erected in one shot rather than floor by floor. “Often you build the first floor, take measurements, then build the second floor,” Overholser says. “The challenge was hitting our heights and trying to keep the whole structure plumb, level, and square while not tied into the flooring systems.”

More costs were trimmed by devising a hybrid framing system of steel and engineered wood. “The whole frame of the house initially was going to be steel, but as we worked toward the body of the structure we transitioned to engineered lumber,” Overholser says. “It ended up being a little trickier because you have different materials running into each other.”

Getting out of the ground correctly is fundamental to any successful project. Although the house size was manageable, it covered a cramped site with no right angles. The original plan was to use helical piers, drilling down rather than removing the unstable soil. But after hitting the old hotel’s “monstrous” foundation, that plan was scrapped. With an engineer watching, the crew spent three days removing the old foundation and digging down 14 feet against the neighbor’s shored-up foundation until they found solid fill. “Luckily, we had dry weather,” Overholser says. More modified soil was trucked in and compacted in 12-inch increments before a new concrete foundation could be poured.

Those difficulties seem negligible now. One benefit of the design-and-engineering collaboration is that, upon approach, the house appears as a robust brick building carved up with mahogany windows, sapele wood cladding, and clear and frosted glass. But the inside is airy and light-filled. “Because of the massively solid brick curve, it reads as an introverted house,” Mileto says. “But from the inside it feels like a predominantly glass building.” The façade’s historic-looking gray brick also negotiates subtle shifts of sensibility and place. A closer look at the clean, wire-cut surface reveals unexpected orange flecks and a bluish iridescence. “It was a design and construction process attuned to detail,” Mileto says. “Every inch is considered.”