The price track

Framing lumber traded at $524.55 per thousand board feet on September 11, according to the Madison's Lumber Price Index figures published by the National Association of Home Builders on September 14. That was 1.2% above the prior week, 2.2% below a month earlier and 8.8% above the same point in 2025.

The August reading tells a different story from a different vantage point. On August 7 the price was $558.19 per thousand board feet — unchanged on the week, 2.1% above a month earlier, and 2.6% below the year-earlier level.

Between those two dates the cash price fell roughly $34, or 6%, while the annual comparison swung from negative 2.6% to positive 8.8%. Both facts are true simultaneously because the year-ago base changed as well as the current price.

The duty structure changed

The trade regime on Canadian softwood lumber was adjusted during the period. The preliminary antidumping rate was cut from 20.6% to 10.7% and the countervailing duty rate from 14.6% to 14.2%, taking the combined duty rate to roughly 25.9% from 35.2%.

A separate Section 232 tariff of 10% remains in place on top of those duties, which brings the total applied rate on Canadian imports to approximately 35.9%.

Analysis: the headline duty reduction of more than nine points is therefore smaller in effect than it sounds, because the Section 232 layer sits above it. The combined rate moved from about 45.2% to about 35.9% — real relief, but leaving a tariff burden that remains high by historical standards.

What lumber does to a house price

Framing lumber is a meaningful but not dominant share of the cost of a single-family home. Moves in the cash price transmit to builder costs with a lag of weeks to months, depending on how far ahead a builder buys and whether it holds inventory.

The more consequential channel in 2026 has been uncertainty rather than level. Duty rates that change mid-year make forward pricing difficult for builders who must quote a house price to a buyer months before the lumber package is purchased.

That uncertainty is one component of the broader cost pressure builders reported this year. In the July NAHB survey, the median builder reported building material costs up 6.7% over the preceding twelve months — an aggregate across all materials, of which lumber is one input.

Reading a weekly commodity series

Madison's index is a trade publication's survey of transaction prices, published weekly, and it is volatile by nature. Week-to-week moves of one or two percent carry little information, and NAHB republishes it precisely because no government series tracks the cash market at that frequency.

Futures prices, published alongside, moved less sharply: up 0.4% on the week and 4.4% year over year as of September 11, against a cash price up 8.8% year over year. A futures market pricing a smaller annual increase than the cash market implies traders do not expect the current cash premium to persist.

For buyers, none of this shows up directly in a house price. It shows up in whether the builder starts the house at all, and at what margin — which is the channel through which input costs actually reach the market.