I've written about this a number of times now. There are different types of precast brick panels.
The cheapest type is where the concrete is laid into a mould with the brick pattern in it already. That stuff is typically erected with the panel in a neutral concrete colour, the bricks getting stained once the panels have been installed on the building face. That's how it was does at King West Life in Liberty Village, for one example.
More frequently these days, bricks, yes actual bricks, are laid into a mould, spacers are placed between them, and then the concrete is then poured in as a structural backing. After curing, the panel is removed from the mould, the spacers are removed, and you've got a real brick panel to hoist into place. This allows builders to put brick high up on buildings without having to erect either massive scaffolds beside the walls, or dropping movable stages over the side.
Besides the more efficient fabrication of the brick panels, the panels are expected to be lower maintenance, longer lasting, and have a higher R value.
When you see varying tones in the bricks of a panel, that's a pretty good indication that you're looking at real brick.
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