My deck boards are cupping after 3 years in Walden. Is this a material defect or did they install them upside down?

Deck board cupping after 3 years is typically caused by improper installation rather than a material defect. The boards were likely installed with the bark side (rounded grain pattern) facing up instead of the heart side (cathedral grain pattern) facing up, which is the opposite of proper installation technique.

Proper deck board installation requires placing boards with the heart side up — you'll see the grain pattern looks like upside-down "U" shapes or cathedrals. When installed this way, any cupping that occurs will create a crown in the center of the board, allowing water to run off the edges. When boards are installed bark-side up (grain looks like right-side-up "U" shapes), they cup into a dish shape that holds water, accelerating rot and creating safety hazards.

Calgary's extreme climate makes proper installation critical. Our chinook weather patterns create rapid freeze-thaw cycles and dramatic moisture changes that stress lumber significantly. In Walden's newer development, many homes were built during Calgary's construction boom when some contractors may have rushed installation details. The combination of our clay soils (which affect drainage around deck footings) and temperature swings from -30°C to +15°C in winter put extra stress on improperly installed decking.

Check your installation method by looking at the end grain of your boards. If you see the curved grain lines forming cups facing upward (like bowls), they're installed incorrectly. Properly installed boards should have the curved grain forming upside-down cups. Also examine the fastening pattern — boards should be secured with two screws or nails per joist, and screws should be stainless steel or galvanized to prevent staining.

Professional assessment recommended since this affects both safety and longevity. A qualified deck contractor can determine if the cupping is severe enough to warrant replacement or if the boards can be flipped and reinstalled. Given that your deck is only 3 years old, this may be covered under your contractor's workmanship warranty if the installation was improper. Document the cupping with photos and contact your original contractor first.

Next steps: Have a licensed contractor inspect the installation and fastening methods. If the original contractor won't address the issue, consider having the boards removed, flipped, and reinstalled properly — this is often more cost-effective than full replacement and will extend your deck's lifespan significantly in Calgary's harsh climate.