Peter Gilgan, the billionaire founder of Mattamy Homes, is diving headfirst into prefab—and not with a pilot project, but a full-scale factory. His new venture, Stelumar Advanced Manufacturing, SAMI, is set to crank out components for mid-rise condos and multi-bed units. They’re targeting a jaw-dropping 3,000 units annually, with operations expected to begin in 2026—and Mattamy Homes locked in as its first customer
This isn’t a side gig—it’s a strategic bet on fixing Toronto’s housing crunch.
What makes this move so striking is the scale and ambition. Stelumar isn’t tinkering around the edges; it’s aiming to slash traditional build times—from years down to months—and cut costs in the process . That ambition aligns neatly with Ottawa’s housing plan: build 500,000 homes per year by 2035, backed in part by a $26B prefab incentive. Gilgan is staking his chips right in the middle of that federal push.
But let’s be honest: prefab isn’t a new experiment in Canada. Mattamy already tried it—back in the Milton facility, they built entire house modules in 11 days and cut onsite timelines by 70 days before relocating the plant. That’s real-world proof this can work—if it’s done right. The challenge has always been scaling, funding, and navigating regional codes—but Gilgan’s deep pockets and Gov’t backing might just break the cycle.
At the end of the day, Gilgan’s game here is twofold: ramp up housing supply and position himself at the cutting edge of factory-built solutions. If Stelumar delivers on its promise, it could shift the timeline, costs, and quality curve of urban housing in Canada. And if he stumbles, we’ll learn just how tough real change remains. The next two years are going to tell us whether prefab goes mainstream—or retreats back to pilot mode.
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Gary Fleisher, The Modcoach, writes about the modular and offsite construction industry at Modular Home Source.
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