How Many Boards for a 12x24 Deck?
Deck boards to buy
52 12 ft boards
288 square feet, 26 rows running the 24 foot way, joists 16 inches on center.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Deck length24 ft
- Deck width12 ft
- Board face width5.5 in
- Gap between boards0.25 in
- Board length you buy12 ft
- Joist spacing on center16 in
Deck boards to buy52 12 ft boards
| Deck area | 288 sq ft |
|---|---|
| Board rows across the width | 26 |
| Linear feet of decking | 624 lf |
| Boards at 12 ft | 52 |
| Joists at 16 in on center | 19 |
The material list this produces
| Deck boards, 12 ft | 52 |
|---|---|
| Joists, 12 ft | 19 |
| Joist hangers, each | 38 |
| Deck screws, lb | 9 |
Board length compared
Same deck, four board lengths. Longer boards mean fewer end joints and more offcut risk.
| Board length | Deck boards to buy |
|---|---|
| 8 ft boards | 78 8 ft boards |
| 12 ft boards | 52 12 ft boards |
| 16 ft boards | 39 16 ft boards |
| 20 ft boards | 32 20 ft boards |
What else matters here
Twenty six rows at 24 feet is 624 linear feet, and since decking is not sold at 24 feet, every row is two 12 foot boards meeting in the middle. Fifty two boards, fifty two butt joints.
Twenty six joints all landing on the same joist is a visible line straight down the middle of the deck and a weak line as well, because that joist is carrying the end of every board on both sides. Stagger them: run the joints across three or four different joists in a repeating pattern so no two adjacent rows break in the same place.
Wherever a joint lands, both board ends need full bearing, which a single 2x8 does not give: an inch and a half of joist split between two boards is three quarters of an inch of bearing each, with the screws right at the end grain. Double the joists that carry joints, or add a sister block, and pre drill the ends so they do not split.
What this calculator assumes
- A nominal 2x6 board is 5.5 inches of actual face. Nominal sizes are not real sizes, which is where most deck orders go wrong.
- Joist count is the span across the deck width at the spacing given, plus one for the last joist.
- Waste is not added. Add 5 to 10 percent if the deck is not a plain rectangle.
Questions people ask
How many boards for a 12x24 deck?
Fifty two boards of 5/4 by 6 at 12 feet, two per row across 26 rows.
How do you stagger deck board joints?
Move the joint to a different joist every row or two in a repeating pattern, so the breaks never line up and never sit next to each other.
Do deck boards need a double joist at a butt joint?
They need full bearing for both ends. A single joist gives each board three quarters of an inch, so double the joist or add a block, and pre drill the ends.
The deck calculator takes any dimensions you like and hands back the same list.