As an Amazon Associate I earn from qualifying purchases.
A 12x24 deck covers 288 square feet and costs about $5,069 – $7,920 installed in pressure-treated pine, up to $11,059 – $17,280 in composite. It takes about 57 decking boards at 20 ft, 19 joists, 4 footings and 48 linear feet of railing.
| Material | Installed cost |
|---|---|
| Pressure-Treated Pine | $5,069 – $7,920 |
| Cedar | $7,373 – $11,520 |
| Redwood | $8,755 – $13,680 |
| Composite (Trex/TimberTech) | $11,059 – $17,280 |
| PVC / Cellular | $13,363 – $20,880 |
| Ipe / Tropical Hardwood | $14,976 – $23,400 |
A 12x24 deck is 288 square feet. In pressure-treated pine, expect roughly $5,069 – $7,920 installed. Cedar runs about $7,373 – $11,520 and composite about $11,059 – $17,280. 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 12 ft direction, you need 26 rows — that is 624 linear feet of decking, or about 57 boards at 20 ft with a waste allowance. At 24 ft there is no stock length that crosses in one piece, so each row takes 2 boards with 1 butt joint that needs blocking beneath it.
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.