Interior designer René Desjardins elevated the spirit of a reconstructed 1960s suburban home in Montreal while tripling its square footage. The centerpiece of the addition is a new anthracite “iron lace” staircase, which was loosely inspired by wooden circle motifs found in the house’s original entryway.

The family who hired Desjardins had two main goals for the addition: It should house their growing modern art collection and provide ample space for frequent entertaining. In terms of aesthetics, “The client wanted something theatrical; I wanted something a little more subdued,” says Desjardins. The lacy, laser-cut iron staircase—fabricated by Jean-François Smith of Artisan de l’Acier—was the happy compromise. To camouflage screws and give the piece fluidity, many layers of car paint were applied to the quarter-inch-thick metal.

Floating gypsum walls and a sliding white wall add contrast to the dark steel railing. The balustrade wraps up to the mezzanine level and encloses a loftlike space, surprising for a bungalow, that allows a bird’s-eye view of the living room below. Desjardins sourced all the main furniture pieces from Minotti, including a Jensen armchair and Mitchell coffee table. Spicing up the dark color palette is a striped Spectrum rug by the Rug Company. The designer chose subtle, gallery-like lighting by EKLIPSE Architectural Lighting: LED rails and back-lit niches complement the owners’ art, particularly a painting by Simen Johans.