The 96-Year-Old Tariff Went Live. Canada Answers September 8.

UPDATE to our August 20 lead. The three-day pause expired without a deal. U.S.-Canada talks collapsed late Friday, August 21, and the 50% Section 338 duties took effect at 12:01 a.m. ET Saturday, August 22 - the first use of the statute in 96 years.

• The optionality is gone. This is now a cost, not a threat.
• The framing lumber in a wall is exempt. The sheathing on it is not.
• Retaliation has a date, and it hits another construction input.

Four days ago this was a scheduled event that had already slipped once. It is now the operative law at the border, and the refund mechanism that applied during the suspension no longer helps anyone.

The carve-out structure is what estimators need to internalize. Section 338 does not apply to articles already under Section 232. Softwood lumber carries a 10% Section 232 duty, so it sits outside the 50%. No grade of plywood carries a Section 232 duty - so plywood is fully exposed, listed across nearly the entire heading.

Read that as a wall assembly. Studs: protected. Sheathing: 50%. Cabinets and vanities: 25% today, 50% in January 2027. Cement: covered.

The September 8 retaliation list extends the problem rather than resolving it. Pulp and paper is on it, and appliances are on it - one a construction input, the other a multifamily unit-turn and delivery cost. A builder gets hit going out as well as coming in.

USMCA origin provides no exemption, which removes the workaround most procurement teams reach for first. Energy, potash, critical minerals and fish are carved out. USTR puts covered trade near $20 billion; two-way trade ran $376 billion in the first half of 2026. The statute carries no expiry and requires no investigation. There is no sunset to underwrite toward.

Implications

For anyone with a GMP signed before August 22, the exposure is live today. The question is not whether costs rise but who absorbs them - and that answer sits in the contract's material escalation and change-in-law language, not in the tariff schedule.

For projects still pricing, the discipline is line-item rather than blanket. A flat contingency bump misprices the risk in both directions, because the duty lands on specific commodity codes and skips others entirely. Sheathing, panel goods, millwork and cement need repricing. Framing lumber does not.

The January 1, 2027 cabinet escalation deserves a place in any schedule extending into next year. A project delivering units in Q1 2027 is buying cabinets into a 50% duty, and that is knowable today rather than a forecast.

The sourcing response has limits worth naming. Canada already ranks behind Indonesia and Vietnam in hardwood plywood shipped to the U.S., and Indonesian panel has its own antidumping exposure. Substitution moves the problem; it does not eliminate it. The genuine uncertainty is duration - this is a bilateral standoff with two governments publicly blaming each other.