Roof decking doesn’t get much attention until it’s rotted through or crushed by a fallen limb. Then a homeowner in Austin or Round Rock finds out the plywood or OSB sheathing under their shingles needs full replacement, not just a patch. That’s when the price of lumber starts to matter more than it used to.

Decking is the layer nobody sees: sheets of oriented strand board or plywood, usually 7/16 or 15/32 inch thick, nailed across the rafters before shingles or underlayment ever go down. Most of the softwood lumber that becomes that sheathing, and the framing lumber behind it, comes from Canada. That supply line has been running through a tariff fight for a while now, and 2026 has not been kind to it.

Canada still supplies most of the wood behind Austin roofs, and that’s the problem

Canada supplied roughly 74% of U.S. softwood lumber imports in 2024. There’s no quick substitute at that scale. Domestic mills can’t fill the gap overnight, and OSB producers, the ones making the sheathing panels that go under shingles on most Austin homes, don’t have unlimited capacity either.

The average tariff on Canadian softwood lumber currently sits above 34%, though there’s talk it could ease later this year if trade negotiations go somewhere. Talk is cheap. A contractor ordering decking material for a fall reroof can’t wait around for a rate cut that may or may not land before the crew shows up.

This isn’t the same tariff story that’s dogged the metal side of construction for the past couple of years. Steel and aluminum pricing has its own separate mess. Lumber and OSB run on a different set of duties, tied to a decades-old dispute over Canadian softwood that keeps getting renegotiated and keeps not getting resolved.

A new 50% tariff proposal adds pressure right as storm season winds down

On July 21, 2026, a fresh proposal surfaced: a 50% tariff on a broader set of Canadian goods, with a 30-day window to strike a deal before it kicks in. Cement, glass, doors and plywood products are named specifically. Plywood is decking material. It isn’t a footnote here.

Analysts at UBS estimate tariffs have added roughly $7,900 to the cost of building a home as of this summer, a figure that bleeds into repair and replacement work too, not just new construction. UBS homebuilding analyst John Lovallo put it plainly: it’s confusing, and even he’s not sure how it shakes out. That’s about as honest a read on the lumber market as anyone’s offered lately.

OSB suppliers, separately, have already raised prices or say they plan to, partly because of higher natural gas costs tied to the Iran conflict earlier in the year. Making sheathing panels takes energy. When that input gets pricier, the panel does too, tariff or no tariff, and the two pressures are landing at the same time rather than one after another.

What this means for a decking replacement bid this fall

An Austin homeowner getting a quote for a full deck tear-off and replacement this fall is pricing lumber in a market that’s moved twice already this year: once on the baseline softwood rate, and again on the broader materials proposal still working through negotiations. Material costs on a bid can drift between the estimate and the day the order actually gets placed, especially on jobs that take weeks to schedule around weather and crew availability. For a roof replacement in Austin involving damaged decking, lumber and OSB pricing can change the final bid even when the shingle choice stays the same.

None of this is unique to Austin. Round Rock and Westlake homeowners are buying the same OSB and the same Canadian dimensional lumber as anyone repairing a roof anywhere else in the country. What’s local is the timing. Storm damage tends to expose decking problems right as this tariff situation stays unresolved, which means a price written down this month may not hold if the material order goes in six weeks from now.

Nobody knows yet whether the rate eases or the new 50% proposal actually takes effect. Both outcomes change what a deck replacement costs, and they point in opposite directions. For now, the safer assumption is that decking material stays the volatile line item on a roofing estimate through the rest of 2026.

There’s a practical wrinkle here too. Roofing contractors who bid a job in June and don’t order material until September are effectively guessing at a moving target, and some are building in a contingency line for lumber the way they used to for asphalt shingles during the petroleum price spikes a few years back. Homeowners comparing bids side by side might notice that gap now shows up as a separate line item instead of getting buried in the total.

Storm damage doesn’t wait for tariff negotiations to settle. A tree limb through a section of decking after a summer thunderstorm still needs replacing that week, whatever the softwood rate happens to be that month. Homeowners in that spot have less room to shop around for better lumber pricing than someone planning a routine reroof months in advance.

Whether the number lands at 34%, 24%, or something new entirely by winter, the underlying supply problem doesn’t go away. Canada is still the source for most of this material, and the U.S. hasn’t built enough domestic milling capacity to change that in a single tariff cycle. That’s the part of the story that outlasts any one headline about a rate change.