Treated deck lumber price in Canada: what deck boards cost at Quebec stores

The table is the price of one 5/4x6x8 brown treated board at each Quebec retailer, seen October 13, 2026. Canac is cheapest at $6.99 and Matério the priciest at $7.98, a gap of $0.99 per board (14 percent).

The listings are close cousins rather than identical boards: each store carries its own treatment brand and grade name, and some sell a "select" or "premium" grade. Look at the face of the board before you buy a pallet.

A "6 inch" board is 5 1/2 inches wide. With a 1/8 inch gap between boards, an 8 ft board covers about 3.75 square feet of deck. For a 100 sq ft deck surface that is 27 boards, or 30 with 10 percent set aside for cuts and defects.

At that count, the surface boards of a 100 sq ft deck cost $210 at the cheapest store we track and $239 at the priciest, before tax. That is the surface only: the frame, posts, railings and fasteners are separate.

Boards come in other lengths too. Matching the board length to your deck width cuts waste, so measure first and then compare prices for the length you need.

A deck is more than its surface. The frame, the joists and the posts are usually pressure-treated too, and the table shows what the common sizes cost today.

Pressure treatment pushes preservative deep into the wood, which is what lets it sit outdoors. Use fasteners rated for treated lumber, such as hot-dip galvanized or stainless steel, because the preservatives corrode plain steel.

Buy boards that are straight and dry to the touch, and store them flat and off the ground until you build. Freshly treated boards that are wet can shrink as they dry, which opens the gaps. Seal or stain the deck once it has dried, following the treatment maker's instructions.

The shelf prices on this page are what Quebec retailers charge. If you build somewhere else, the best official yardstick we have is Statistics Canada's building construction price index, which follows what builders pay for wood, plastics and composites in a single-detached house in each province.

Quebec, where our shelf prices come from, reads 118.8, up 5.0% on a year earlier. That is the highest of the 9 provinces Statistics Canada tracks, and Ontario is lowest at 97.4 in the second quarter of 2026. These are cost indexes set to 100 in a base period: they say how fast lumber and panel costs have moved in each province, not what a single item sells for at your local store. We will publish real shelf prices for your province as it goes live.