Materials for a 20×24 deck
71 deck boards (16 ft)
for 480 sq ft: 43 rows of 5½ in boards with a ⅛ in gap, on 19 joists, with 10% extra.
For a 20×24 foot deck, the boards run along the 24 ft side and the joists span the 20 ft side. At 24 ft you will need to join boards over a joist; stagger the joins from row to row.
Materials for a 20×24 deck
| Deck area | 480 sq ft |
|---|---|
| Deck boards (5½ in × 16 ft) | 71 |
| Linear feet of decking | 1,032 ft (+10% = 1,135 ft) |
| Joists at 16 in on center | 19 × 20 ft |
| Joists at 12 in on center | 25 × 20 ft |
| Rim joists | 2 × 24 ft |
| Deck screws | about 1,634 |
Framing sizes (joist depth, beams, posts and footings) depend on spans and local code; check your building department’s deck guide before you build.
Change the numbers
Other deck sizes
- 18×24 deck
- 20×20 deck
- 16×24 deck
- 24×24 deck
- 18×20 deck
- 14×24 deck
- 16×20 deck
- 12×24 deck
- 14×20 deck
- 10×24 deck
- 12×20 deck
- 10×20 deck
Questions
- How many deck boards do I need for a 20×24 deck?
- 71 boards 16 ft long (5½ in wide), laid in 43 rows, including 10% extra.
- How many joists for a 20×24 deck?
- 19 joists 20 ft long at 16 in on center, or 25 at 12 in on center.
- How many screws for a 20×24 deck?
- About 1,634 deck screws: two per board at each joist. A 5 lb box holds roughly 350 to 450 screws.
- How much does a 20×24 deck cost?
- Decking boards alone run about $1,816 in pressure-treated pine or $4,541 in composite. A finished 480 sq ft deck built by a contractor typically costs $14,400 to $28,800.