A deck takeoff combines a framing takeoff (joists, beams, posts — similar math to floor framing) with a decking-specific material list for the visible surface.
Decking boards
Decking boards are calculated from deck square footage divided by the coverage per board (board width plus gap spacing, typically 1/8"–3/16" for composite, slightly more for wood to allow for expansion) — waste runs higher than interior flooring, typically 10–15%, to account for end-cuts and staggered seams.
Framing
Framing follows standard joist-span math, but decks have their own span tables distinct from interior floor framing, since deck joists are often pressure-treated lumber with different allowable spans than interior dimensional lumber, and ledger attachment to the house requires specific flashing and fastening detail that a takeoff should account for separately.
Fasteners
Fasteners vary significantly by decking material — hidden fastener systems for composite decking cost more per square foot than visible screws for wood decking, and this choice affects both material cost and labor time (hidden systems are generally slower to install).
Guardrails and stairs
Guardrails and stairs, when part of the scope, should be taken off separately by linear footage of railing and stair stringer/tread count — these are frequently underpriced because they're treated as an afterthought to the deck surface itself rather than their own material and labor category.