Site size: 174,240 square feet Project size: 4,000 square feet

Program: The clients wanted the house—which is situated on a ravine near the city center—to have a strong connection between indoor and outdoor spaces, and to encompass a modernist sensibility, with every space and site line being fully considered. 

Location: Toronto, Ontario, Canada

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Solution: A stipulation of a 1950s-era zoning law required a setback from the top of the ravine, in turn influencing the house’s shape, which takes the form of three stacked volumes. Each of the house’s levels shifts in response to its own set of criteria: zoning, views both into and out of the house, daylight, and structural design. The site offered opportunities for expansive glazing to the rear without concerns for privacy and quiet. This allowed for protected outdoor spaces, including a terrace to the west of the middle volume, which provides a covered space for outdoor cooking and dining. In accordance with site constraints specifying a compact footprint for the lower floor, main living spaces were placed in the middle volume and cantilevered to the rear, with views directly to the treetops.

Construction and materials: Concrete was selected for its durability, strength, and potential for vertical and horizontal application, as well as for its aesthetic. The architect employed a building system of cast-in-place concrete sandwich panels: the inner layer of concrete is structural, the outer one forms the cladding. Between the two is a continuous layer of extruded polystyrene insulation. With the concrete left exposed on both sides, this construction method allowed the exterior cladding, insulation, vapor barrier, structure, and interior wall finishes to be completed in a single casting.

Completion date: January 2015


Additional Information

Total project cost: Withheld

Client: John Pylypczak and Diti Katona



Angela Tsementzis Architect

+1 416-564-4268


Personnel in architect's firm who should receive special credit:

Partner in Charge - Angela Tsementzis, OAA



Structural Engineer – Blackwell Structural Engineers


General contractor:

Marcus Design Build  



Bob Gundu — +1 416-876-4621; Colin Faulkner — +1 416-469-1557



North Design Office





Structural System

Cast-in-place concrete sandwich panels


Exterior Cladding

Masonry: Thermomass

Curtain wall: Alumicor  

Other cladding unique to this project: Sto cladding at upper floor



Built-up roofing: Soprema



Metal frame: Door Studio



Sliding doors: Door Studio

Wood doors: Solid core wood framed doors



Locksets: Omnia

Pulls: Omnia


Interior Finishes

Cabinetwork and custom woodwork: Bulthaup kitchen cabinets; Duravit bathroom cabinets; other millwork custom by O’Sullivan Millwork

Paints and stains: C2 Pain

Solid surfacing: Corian custom sink at master bath

Special interior finishes unique to this project: Admonter engineered wood flooring at upper floor



Downlights: Delta



Water fixtures: Vola and Duravit bathroom fixtures