Deck materials

Pressure-treated pine is the default and the cheapest, at $3 to $8 per square foot in material. The tradeoff is maintenance: restaining and sealing every two to three years, at $2 to $5 per square foot each time. Note one detail most homeowners never hear — aluminum should not be in direct contact with lumber treated with copper-based preservatives such as ACQ, Copper Azole, or ACZA, and all cut ends must be field-treated with an approved preservative.

Cedar and redwood are naturally durable species. Under the standard deck construction guide, redwood and western cedars count as naturally durable when 90 percent or more of the width on each side is heartwood; otherwise the lumber must be preservative-treated. That distinction is a real quality difference between two boards that look similar in the yard.

Composite and PVC buy back maintenance. Composite installs at $28 to $40 per square foot with an expected life around 20 years and much less upkeep than wood. PVC/vinyl runs $17 to $33. Neither is maintenance-free — they still need cleaning — but neither needs staining.

Framing is a material decision too. Whatever you walk on, the frame is almost always treated lumber, and its species controls how far joists can span: at 16 inches on center, a 2x8 southern pine joist spans up to 11 feet 10 inches, Douglas fir-larch/hem-fir/SPF 11 feet 1 inch, and redwood or western cedars 10 feet 7 inches. Ledger boards must be a minimum nominal 2x8, and joists or rim joists that guard posts attach to must also be at least 2x8.

How to choose

Choose on maintenance appetite, not on board looks

Wood needs restaining every two to three years at $2 to $5 per square foot. If you know you won't do that, buy composite or accept a 10 to 15 year deck.

Ask for the species and grade of the framing lumber

Species changes allowable joist span by more than a foot in typical sizes. It should be named in the contract, not assumed.

Match fasteners to the material and the environment

Fasteners and connectors within 300 feet of a saltwater shoreline must be stainless steel grade 304 or 316. Mixing metals is a corrosion failure waiting to happen.

Ipe and mahogany are a commitment

At $30 to $55 per square foot installed, exotic hardwood is premium money. It is a beautiful deck and a bad place to economize on the frame beneath it.

Get the actual product name in writing

"Composite" spans a wide price and quality range. The contract should name the exact product line, not a category.