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.
Assumptions to Check
Before ordering materials, confirm the dimensions, product coverage, waste factor, and local installation requirements for your project. Manufacturer coverage tables and local code rules can change the final quantity, especially for structural work, exterior projects, and irregular layouts.
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