Materials for a 8×20 deck
20 deck boards (20 ft)
for 160 sq ft: 18 rows of 5½ in boards with a ⅛ in gap, on 16 joists, with 10% extra.
For a 8×20 foot deck, the boards run along the 20 ft side and the joists span the 8 ft side.
Materials for a 8×20 deck
| Deck area | 160 sq ft |
|---|---|
| Deck boards (5½ in × 20 ft) | 20 |
| Linear feet of decking | 360 ft (+10% = 396 ft) |
| Joists at 16 in on center | 16 × 8 ft |
| Joists at 12 in on center | 21 × 8 ft |
| Rim joists | 2 × 20 ft |
| Deck screws | about 576 |
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
- 8×18 deck
- 8×16 deck
- 8×24 deck
- 10×20 deck
- 8×14 deck
- 8×12 deck
- 8×10 deck
- 12×20 deck
- 8×8 deck
- 14×20 deck
- 16×20 deck
- 18×20 deck
Questions
- How many deck boards do I need for a 8×20 deck?
- 20 boards 20 ft long (5½ in wide), laid in 18 rows, including 10% extra.
- How many joists for a 8×20 deck?
- 16 joists 8 ft long at 16 in on center, or 21 at 12 in on center.
- How many screws for a 8×20 deck?
- About 576 deck screws: two per board at each joist. A 5 lb box holds roughly 350 to 450 screws.
- How much does a 8×20 deck cost?
- Decking boards alone run about $634 in pressure-treated pine or $1,584 in composite. A finished 160 sq ft deck built by a contractor typically costs $4,800 to $9,600.