Complete 10x20 Deck Material List & Selection Framework

The 10x20 Deck Material Selection Framework

Designing a 10x20 deck (200 square feet) requires balancing structural load paths, local climate demands, and surface material longevity. A common failure mode in residential deck building is selecting the surface material before finalizing the substructure spacing. Composite and PVC decking often mandate 12-inch on-center (OC) joist spacing, whereas traditional pressure-treated (PT) lumber allows 16-inch OC. This single decision cascades through your entire material list, altering lumber counts, fastener quantities, and overall budget.

Substructure & Footing Material List

The substructure accounts for roughly 35% of your total material cost but dictates the deck's lifespan. According to the American Wood Council's Prescriptive Residential Deck Construction Guide, a 10x20 deck attached to a home typically utilizes a 20-foot ledger board with joists projecting 10 feet outward. Assuming a 40 PSF live load and 10 PSF dead load, here is the exact framing list for a 16-inch OC layout (suitable for standard wood or straight-laid premium composite).

Footings & Posts

• Footings: (3) 12-inch diameter Sonotubes or Bigfoot Systems BF-24 footings. Depth must extend below your local frost line (e.g., 36 inches in Zone 5, 48 inches in Zone 6).
• Concrete: 24 bags of 80-lb high-strength (4000 PSI) concrete mix per footing, or 1.5 cubic yards of ready-mix delivery.
• Posts: (3) 6x6x8' #2 Southern Yellow Pine (SYP) or Douglas Fir, ground-contact rated (UC4A or higher).
• Post Bases: (3) Simpson Strong-Tie EPB66Z or equivalent elevated post bases to keep wood 1 inch above concrete.

Beams, Joists, & Ledger

• Ledger Board: (1) 2x10x20' PT lumber. Must be flash-sealed against the house rim joist.
• Carry Beam: Built-up beam requiring (6) 2x10x10' PT lumber, staggered and nailed together to form a 3-ply 2x10 beam spanning the 20-foot width. Placed 8 feet from the house to allow a 2-foot cantilever.
• Joists: (16) 2x8x10' PT joists, plus (2) 2x10x20' rim joists.
• Joist Tape: (4) rolls of butyl joist flashing tape (e.g., Trex Protect or G-Tape). Critical for composite decks to prevent moisture trapping and joist rot.

Decking Surface Quantities & 2026 Pricing

Calculating surface materials requires accounting for the actual face width of the boards and a mandatory waste factor. Standard 5.5-inch wide decking yields a coverage of 0.458 square feet per linear foot. For a 200 sq ft deck, you need 436 linear feet of decking. Adding a 10% waste factor for straight layouts (or 15% for diagonal) brings the requirement to 480 linear feet.

Fasteners, Flashing, and Code-Compliant Hardware

Hardware failures, specifically ledger board detachment and joist hanger corrosion, are the leading causes of catastrophic deck collapses. Because modern PT lumber is treated with alkaline copper quaternary (ACQ) or copper azole, which are highly corrosive to standard metals, all hardware must be Hot-Dipped Galvanized (HDG) per ASTM A153 or ZMAX/Stainless Steel.

The Hardware Procurement List

• Ledger Fasteners: (14) 1/2-inch x 3-inch HDG lag screws or Simpson SDWS structural screws, staggered in two rows along the 20-foot ledger. Must penetrate the house rim joist by at least 1.5 inches.
• Joist Hangers: (16) Simpson LUS28-2Z (for 2x8 joists) and (2) LUS210-2Z (for rim joist connections).
• Hanger Nails: 2 lbs of 10d x 1.5-inch HDG joist hanger nails. Never use standard galvanized roofing nails or screws in joist hangers.
• Beam-to-Post Connectors: (3) Simpson APCB44Z or similar post caps to secure the built-up beam to the 6x6 posts.
• Decking Fasteners:
  • For Wood: 1 box (350 ct) of #9 x 3-inch polymer-coated star-drive deck screws.
  • For Composite/PVC: 1 box (350 ct) of color-matched composite face screws, plus (1) box of hidden stainless steel start/stop clips and universal hidden fasteners (approx 250 clips for 16-inch OC spacing).
• Flashing: (1) 20-foot roll of Z-flashing or continuous self-adhering membrane (e.g., Trex Seal) for the ledger board top edge to prevent water intrusion behind the house siding.

Railing & Stair Component Breakdown

Any deck surface elevated more than 30 inches above grade requires a code-compliant guardrail. For a 10x20 deck with a 4-foot elevation, you will need railing on the two 10-foot sides and the 20-foot front, minus any stair openings. Assuming one 4-foot stairway on the front, you need 36 linear feet of railing.

Stair Stringers & Treads

For a 48-inch total rise, you will need a 5-tread stair stringer. According to Trex installation guidelines and general composite stair specs, composite treads require a maximum stringer spacing of 12 inches OC. Therefore, a standard 36-inch wide staircase requires four stringers, not three.

• Stringers: (4) 2x12x10' PT pre-cut stair stringers.
• Treads: (10) composite stair treads (12-inch depth x 48-inch width) or standard 5/4x6 decking boards cut to length (3 per step).
• Stringer Mounts: (4) Simpson LSC4Z adjustable stringer connectors to attach to the rim joist without notching the wood.

Procurement Strategy & Waste Allowances

When ordering materials for a 10x20 deck, coordinate delivery in two phases to prevent site damage and warping. Phase 1 should include all PT framing lumber, concrete, and hardware. Allow the PT lumber to dry and acclimate for 48 hours before framing. Phase 2 should consist of the composite/PVC surface boards, hidden fasteners, and railing kits. Store composite boards flat on a level surface, fully supported every 4 feet, and keep them covered with the manufacturer's reflective wrap until installation to prevent thermal warping from direct sun exposure prior to fastening.

Always verify your local municipality's specific amendments to the IRC. Some jurisdictions require engineered stamped plans for decks exceeding 200 square feet or those attached to masonry veneer homes, which will alter your ledger fastening material list from standard lag screws to specialized masonry anchor systems.