Deck Building Guide

Plan the Deck

Before buying materials, lock down the finished dimensions, deck height and how the deck is supported.

• Decide the deck footprint (length and width) to the outside of the framing.
• Confirm the support method: on piers, posts, or attached to the house.
• Check local code for joist spacing, railing height and ledger requirements.

Calculate the Framing

Framing starts with the ledger board, then joists run perpendicular to it. Beam and post spacing depends on the joist span you choose.

Common joist spacing is 16" on center for decking; use 12" for heavier loads or diagonal board layouts. Estimate one extra joist for the end framing.

Estimate Decking Boards

Decking boards run across the framing. For perpendicular 5/4 or 2x boards, count the rows first, then multiply by the deck length.

1. Measure the board length

   Each row runs the full deck length, so note that dimension.

2. Count the rows

   Divide deck width by board width plus your gap, then round up.

3. Add wastage

   Add 10% for cuts, bad boards and layout adjustments.

Fasteners and Hardware

• Choose coated or stainless screws for outdoor exposure.
• Distance between screws follows the board-joining pattern; plan about 2 screws per joist crossing per board.
• Account for joist hangers, flashing and ledger hardware in your cost.

Related Calculators

Related Calculators