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About 3.5 deck screws per square foot — two at every joist on 5½ in boards with joists 16 in on centre, plus 10% for ends and butt joints. A 12 × 16 deck (192 sq ft) takes about 670 screws: 7.5 lb or two 5 lb boxes of 2½ in #9 deck screws, roughly $40. At 12 in joist spacing it is 4.6 per sq ft.
With these inputs:
| Result | Value |
|---|---|
| Deck screws needed | 697 |
| Screws per sq ft (incl. 10%) | 3.5 |
| Pounds (2-1/2 in #9) | 8 lb |
| 5 lb boxes | 2 |
| Estimated cost | $42 |
Includes 10% extra. Use screws rated for treated lumber (coated or stainless); stainless within sight of salt water. Structural hangers, lags and bolts are separate.
Fastener counts are easy to underestimate and unpleasant to run short of halfway through a deck. The number depends on the joist spacing, the board length and whether you are face-screwing or using hidden clips. This counts every screw or hidden clip from your deck size, joist spacing and board width, then converts it into pounds, boxes and cost so you buy the right amount the first time.
About 3.2 screws per square foot, or 3.5 with a 10% allowance, for 5½ inch boards on joists 16 inches on centre with two screws per joist. At 12 inch spacing it is 4.6 per square foot and at 24 inches 2.3.
About 670 screws for 192 square feet at 16 inch joist spacing: roughly 7.5 lb, or two 5 lb boxes of 2½ inch #9 deck screws, at about $40. A 10x10 deck needs about 350 and a 16x20 about 1,120.
About 85 to 95 of the standard 2½ inch #9 deck screw, so a 5 lb box holds roughly 425 to 475 and a 25 lb bucket about 2,200. Three inch screws for 2× decking run 70 to 75 per pound.
Two screws per board at every joist crossing. At 16 inches on centre, a 16 ft board crosses 13 joists, so 26 screws a board. A 16 by 12 ft deck with 26 rows works out around 676 screws, or roughly 3.5 screws per square foot. Buy by the pound with 10 percent spare — the last thing you want is a second trip with four boards to go.
They look considerably better and they leave no screw heads to collect water, which matters on composite. The costs are money and time: clips run around $1.60 to $2.80 per square foot against roughly half that for screws, and they are slower to install. They also make a single damaged board much easier to replace later, which face screwing does not.
Screws rated for contact with modern preservative treatments — stainless steel, or a coated deck screw whose manufacturer lists it for ACQ, CA or MCA-treated lumber. Plain zinc-plated screws corrode in treated wood, sometimes within a couple of seasons, and the streaks they leave are permanent. Stainless is required near salt water.
Yes, wherever a joist ends against a ledger or a rim rather than bearing on top of a beam. Use hangers rated for exterior use and fill every nail hole with the hanger nails the manufacturer specifies — not deck screws, which have no rated shear capacity. Hangers left half-nailed carry a fraction of their rated load.
Roughly 425 to 475 of the common 2 1/2 inch #9 deck screws in a 5 lb box, or about 85 to 95 per pound, so a 25 lb bucket holds about 2,100 to 2,400. Longer 3 inch screws come in around 70 to 75 per pound — about 1,750 to 1,900 in 25 lb. A 200 square foot deck needs about 700 screws, so two 5 lb boxes; a 25 lb bucket covers roughly 600 to 680 square feet at 3.5 screws per square foot.
One clip per board per joist crossing — about 1.7 clips per square foot at 16 inch joist spacing with 5 1/2 inch boards, including a small allowance. Most clip kits hold 90 clips and cover about 50 square feet. The first and last boards and any border are face-screwed, so buy a small box of colour-matched screws as well.
Two at every joist the board crosses. A 16 ft board on joists at 16 inches on centre crosses 13 joists, so it takes 26 screws; at 12 inch spacing it crosses 17 joists and takes 34. Keep screws about 3/4 inch from the board edge and pre-drill near the ends to stop splitting.
About 0.04 lb per square foot, or 4 lb per 100 square feet, for 2 1/2 inch screws at roughly 90 per pound and 3.5 screws per square foot. A 200 square foot deck needs about 8 lb, so two 5 lb boxes. Use 3 inch screws (about 70 to 75 per pound) and it rises to roughly 5 lb per 100 square feet.
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