US tariffs hit Canadian construction through three channels in 2026. First, Section 232 tariffs on steel, aluminum, and copper were restructured on April 6, 2026 into tiered rates of 10 to 50 percent charged on the full customs value of in-scope products, with goods under 15 percent metal content by weight exempt. Second, softwood lumber carries a 10 percent Section 232 tariff on top of combined anti-dumping and countervailing duties of roughly 14 percent, for a stacked burden around 24 percent. Third, Canada's response, including reciprocal measures on US steel and aluminum, a $1.5 billion support package announced May 4, 2026, and dollar-for-dollar retaliatory tariffs beginning September 8, 2026, raises the cost of US-sourced materials and equipment coming north. The scopes most exposed on an Ontario project are structure, mechanical and electrical equipment, curtain wall, and elevators. Wood-frame low-rise is the least exposed structure type.
Tariffs show up in an Ontario pro forma long before any material crosses a border. When the United States charges up to 50 percent on steel and aluminum and Canada answers with dollar-for-dollar counter-tariffs, the entire North American supply chain reprices, and a Toronto tender absorbs that repricing even when every tonne of steel in the building is domestic. This page maps how the 2026 tariff structure actually works and which lines of a construction budget carry the exposure.
| Measure | Rate | How it applies |
|---|---|---|
| Section 232: steel, aluminum, copper | 10 to 50 percent, tiered | Restructured April 6, 2026. Charged on the full customs value of in-scope products, not just the metal content. Under 15 percent metal content by weight is exempt |
| Section 232: softwood timber and lumber | 10 percent | Layered on top of existing trade duties |
| Anti-dumping and countervailing duties on lumber | ~14 percent combined | Applies to most Canadian softwood exporters, for a stacked burden around 24 percent |
The April 6 restructuring matters more than the headline rate. Charging the tariff on full customs value instead of metal content means a fabricated product that is mostly steel by weight pays the tariff on its entire price, labour and margin included. The 15 percent metal-content exemption spares light-content goods, but structural steel, rebar, aluminum curtain wall, and metal-heavy equipment sit squarely in scope.
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Check my site →The uncomfortable arithmetic for a builder: both directions of the trade war are inflationary for a Canadian project. US tariffs reprice the continental market for metals; Canadian counter-tariffs directly tax the US-made equipment and products that have no domestic substitute on the timeline of a live project.
| Scope | Exposure | Why |
|---|---|---|
| Structural steel and rebar | High | Directly in Section 232 scope; continental pricing reprices even domestic supply |
| Mechanical, electrical, elevators | High | Metal-heavy equipment, much of it US-sourced and exposed to Canadian counter-tariffs |
| Curtain wall and cladding | High | Aluminum content puts most systems in scope |
| Concrete | Moderate | Rebar and embedded steel carry the tariff; cement itself does not |
| Wood framing | Low | Lumber duties run export-direction; domestic lumber for domestic use is unaffected, and prices sit roughly 60 percent below the 2021 peak |
| Sitework and earthworks | Low | Fuel and equipment hours, limited tariff content |
The lumber tariffs are charged by the US on Canadian exports. They hurt Ontario sawmills and exporters, but they do not add cost to Canadian lumber bought for a Canadian site. For an Ontario builder, lumber is the cheap scope in 2026, which is part of why wood-frame low-rise is the best-costed product type right now.
They are US Section 232 national-security tariffs on steel, aluminum, and copper. Restructured on April 6, 2026, the tariffs run in tiers from 10 to 50 percent and are charged on the full customs value of in-scope products rather than just the metal content, with goods under 15 percent metal content by weight exempt. Structural steel, rebar, and aluminum systems sit at the high end of the range.
Three ways: metals are priced continentally, so US tariffs lift North American benchmarks and Canadian mill quotes rise even for domestic supply; Canadian counter-tariffs directly increase the landed cost of US-made equipment and materials on Canadian sites; and uncertainty pushes suppliers to shorten price-validity windows, which moves risk into contractor contingencies. Steel-heavy scopes on Ontario projects rose close to 12 percent in the most recent index readings.
The US charges a 10 percent Section 232 tariff on softwood timber and lumber on top of combined anti-dumping and countervailing duties of roughly 14 percent, a stacked burden around 24 percent for most Canadian exporters. These are export-direction duties: they hurt Canadian sawmills selling into the US but do not raise the price of Canadian lumber bought for a Canadian project.
Canada applies reciprocal tariffs on US steel, aluminum, and other products, announced a $1.5 billion support package on May 4, 2026 including a BDC program for businesses reliant on steel, aluminum, or copper, and announced dollar-for-dollar retaliatory tariffs beginning September 8, 2026. For builders, the retaliation matters most where equipment is specified from US manufacturers.
Structural steel, rebar, aluminum curtain wall and cladding, and metal-heavy mechanical, electrical, and elevator equipment carry the highest exposure. Concrete is moderately exposed through its embedded steel. Wood framing and sitework carry the least, which combined with lumber prices roughly 60 percent below their 2021 peak makes wood-frame low-rise the least tariff-exposed way to build in Ontario in 2026.
PreBuildIQ maps any Ontario address to its approval path, required studies, and cost drivers in 60 seconds, so the entitlement side of your budget is nailed down while the tariff side moves.
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