How many deck screws per board?
Quick Answer
The standard is 2 deck screws per joist per board — one on each side of the center of the board. A 16-foot deck board on joists at 16-inch centers crosses 13 joists, needing 26 screws per board. For 5/4×6 composite boards, some manufacturers require 3 screws per joist to prevent cupping.
Quick Reference Table
| Board length | Screws per board (16" joist spacing) |
|---|---|
| 8 ft board | 14 screws |
| 10 ft board | 16 screws |
| 12 ft board | 20 screws |
| 16 ft board | 26 screws |
| 20 ft board | 32 screws |
| 24 ft board | 38 screws |
How to Calculate It Yourself
- 1
Count joist crossings per board: board length ÷ joist spacing + 1. For 16 ft at 16" OC: (192 ÷ 16) + 1 = 13 joists.
- 2
Multiply by 2 screws per joist: 13 × 2 = 26 screws per board.
- 3
Count total boards in your deck, multiply to get total screws.
- 4
Add 10% extra for drops, damaged screws, and starting/ending boards.
Pro Tip
For a 200 sq ft deck with 16-ft boards on 16" centers, you'll use roughly 5 lbs of #10 × 2-1/2" screws. Buy a 5-lb box (about 500 screws) — it's cheaper per screw than smaller quantities and covers you for a few mistakes.
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