Materials for a 16×20 deck
39 deck boards (20 ft)
for 320 sq ft: 35 rows of 5½ in boards with a ⅛ in gap, on 16 joists, with 10% extra.
For a 16×20 foot deck, the boards run along the 20 ft side and the joists span the 16 ft side.
Materials for a 16×20 deck
| Deck area | 320 sq ft |
|---|---|
| Deck boards (5½ in × 20 ft) | 39 |
| Linear feet of decking | 700 ft (+10% = 770 ft) |
| Joists at 16 in on center | 16 × 16 ft |
| Joists at 12 in on center | 21 × 16 ft |
| Rim joists | 2 × 20 ft |
| Deck screws | about 1,120 |
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
- 16×18 deck
- 14×20 deck
- 18×20 deck
- 16×16 deck
- 16×24 deck
- 12×20 deck
- 20×20 deck
- 14×16 deck
- 10×20 deck
- 12×16 deck
- 8×20 deck
- 10×16 deck
Questions
- How many deck boards do I need for a 16×20 deck?
- 39 boards 20 ft long (5½ in wide), laid in 35 rows, including 10% extra.
- How many joists for a 16×20 deck?
- 16 joists 16 ft long at 16 in on center, or 21 at 12 in on center.
- How many screws for a 16×20 deck?
- About 1,120 deck screws: two per board at each joist. A 5 lb box holds roughly 350 to 450 screws.
- How much does a 16×20 deck cost?
- Decking boards alone run about $1,232 in pressure-treated pine or $3,080 in composite. A finished 320 sq ft deck built by a contractor typically costs $9,600 to $19,200.