What Size Screws for Deck Boards (5/4 vs 2x6)
Deck boards need 1-1/2 in of joist bite past the board: #8 or #10 x 2-1/2 in for standard 5/4 decking, 3 in for 2x6 boards. Stainless #10 for hardwoods and coast; coated #8 for inland PT pine. Two screws per joist, every joist — decking cups on single fasteners.
What to Look For
- 5/4 decking (1-in actual): #8 or #10 x 2-1/2 in — 1-1/2-in joist bite.
- 2x6 boards (1-1/2-in actual): #10 x 3 in.
- Hardwood and ipe: #10 stainless — #8 snaps in dense grain.
- Two screws per board per joist — one cups.
- Keep 3/4 in from board ends — closer splits.
Top Picks
1. GRK R4 #10 x 2-1/2-in multipurpose screws Best overall
The 5/4 decking screw — serrated threads, no-split point, exterior-rated.
Check price on Amazon →2. Simpson Strong-Tie Deck-Drive DSV 3-in coated screws For 2x6
Extra length and polymer coating for thick boards and ground contact.
Check price on Amazon →3. Eagle Claw 304 stainless #10 x 2-1/2-in deck screws Best stainless
For cedar, hardwood, and coast — never streaks, never surrenders.
Check price on Amazon →What to Avoid
Avoid
- Drywall screws — they rust and snap under deck loads.
- 2-in screws in 5/4 decking — barely 1-in bite, boards lift.
- Uncoated brights — rust streaks in one season.
Also in the toolbox
- Deck board spacing tool (3-pack) — even gaps without eyeballing
- Impact driver plus spare battery — a deck is a thousand screws
FAQ
#8 or #10 deck screws?
#8 handles standard 5/4 PT pine and cedar fine. Step up to #10 for 2x6 boards, hardwoods, and stainless (softer metal needs the diameter). When in doubt, #10 x 2-1/2-in is the one-box answer for a whole deck.
How many screws per deck board?
Two per joist crossing — a 12-ft board over joists at 16-in centers takes about 20 screws. Budget roughly 350 screws per 100 square feet of deck, and buy the 5-lb box.
Screws or hidden fasteners for decking?
Hidden fasteners win on looks for grooved composite and premium hardwood. Screws win on cost, speed, and repairability — and face screws are mandatory for 2x6 and non-grooved boards. Most wood decks screw; most high-end composite hides.
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