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A 10x20 deck covers 200 square feet and costs about $3,520 – $5,500 installed in pressure-treated pine, up to $7,680 – $12,000 in composite. It takes about 24 decking boards at 20 ft, 16 joists, 4 footings and 40 linear feet of railing.
| Material | Installed cost |
|---|---|
| Pressure-Treated Pine | $3,520 – $5,500 |
| Cedar | $5,120 – $8,000 |
| Redwood | $6,080 – $9,500 |
| Composite (Trex/TimberTech) | $7,680 – $12,000 |
| PVC / Cellular | $9,280 – $14,500 |
| Ipe / Tropical Hardwood | $10,400 – $16,250 |
A 10x20 deck is 200 square feet. In pressure-treated pine, expect roughly $3,520 – $5,500 installed. Cedar runs about $5,120 – $8,000 and composite about $7,680 – $12,000. Building it yourself typically removes 40 to 55 percent of those figures, because labour is around half of a finished deck price.
Laying boards across the 10 ft direction, you need 22 rows — that is 440 linear feet of decking, or about 24 boards at 20 ft with a waste allowance. A 20 ft board crosses the deck in one piece, so there are no butt joints.
About 4, one under each post, with posts at no more than 8 feet along the beam. That is roughly 0.49 cubic yards of concrete for 12 inch tubes poured 42 inches below grade — around 23 eighty-pound bags. Your own frost depth sets the real number and is not negotiable.