The trade relationship between Canada and the United States, stable for decades under successive agreements, deteriorated sharply in the first quarter of 2025 when the Trump administration imposed a 25 per cent tariff on most Canadian goods and a 50 per cent tariff on Canadian steel and aluminum. Canada responded with retaliatory tariffs on $155 billion of American imports, including construction-critical materials.
The Canadian construction industry found itself on both sides of that equation.
An Altus Group analysis estimated that Canada's exposure to American construction inputs, materials and labour combined, represents roughly 8.1 per cent of total construction costs, or approximately $33.1 billion nationally. That figure sounds manageable until you look at where it concentrates. Roughly 40 per cent of HVAC and mechanical equipment used in Canadian construction is sourced from the United States. Boilers, chillers, and fabricated steel components cross the border and, under the 2025 tariff regime, face compounding duties when Canadian steel is used to manufacture American products that are then imported back into Canada.
Lumber tells a different story. Canada is a major softwood lumber exporter to the United States, and American tariffs on Canadian lumber reached a combined rate approaching 45 per cent in 2025. Those tariffs were intended to protect American mills. The effect on American homebuilders was higher input costs. The effect on Canadian producers was market access disruption and price pressure at home as supply rerouted.
For Canadian contractors working on fixed-price contracts, the tariff environment created immediate legal exposure. Standard fixed-price contracts place tariff cost risk on the contractor unless specific escalation clauses exist. BDO Canada estimated that Canadian counter-tariffs alone were projected to increase infrastructure project costs by $1 billion over two years. Contractors without escalation language in their agreements absorbed those increases directly.
By September 2025, Canada removed counter-tariffs on most American imports after the United States agreed to restore tariff-free access for CUSMA-compliant goods. Counter-tariffs on steel, aluminum, and automobiles remained in place, as the United States maintained tariffs on those sectors regardless of CUSMA compliance.
The net effect for the Canadian construction industry is a cost environment that has not returned to pre-2025 baselines. Material costs that spiked during the tariff escalation period did not fully retreat when the tariffs were partially unwound. Contractors who absorbed cost overruns during the peak period did not recover those margins. And procurement teams across the country began, for the first time in a generation, seriously evaluating domestic sourcing alternatives for materials that had always been purchased across the border as a matter of habit and price efficiency.
That shift, if it sustains, has long-term implications for Canadian manufacturing and supply chain investment. The tariff episode was disruptive. Its secondary effect, a serious national conversation about domestic material supply capacity, may prove more consequential than the tariffs themselves.
