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A 10x12 deck covers 120 square feet and costs about $2,112 – $3,300 installed in pressure-treated pine, up to $4,608 – $7,200 in composite. It takes about 24 decking boards at 12 ft, 10 joists, 3 footings and 32 linear feet of railing.
| Material | Installed cost |
|---|---|
| Pressure-Treated Pine | $2,112 – $3,300 |
| Cedar | $3,072 – $4,800 |
| Redwood | $3,648 – $5,700 |
| Composite (Trex/TimberTech) | $4,608 – $7,200 |
| PVC / Cellular | $5,568 – $8,700 |
| Ipe / Tropical Hardwood | $6,240 – $9,750 |
A 10x12 deck is 120 square feet. In pressure-treated pine, expect roughly $2,112 – $3,300 installed. Cedar runs about $3,072 – $4,800 and composite about $4,608 – $7,200. 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 264 linear feet of decking, or about 24 boards at 12 ft with a waste allowance. A 12 ft board crosses the deck in one piece, so there are no butt joints.
About 3, one under each post, with posts at no more than 8 feet along the beam. That is roughly 0.37 cubic yards of concrete for 12 inch tubes poured 42 inches below grade — around 17 eighty-pound bags. Your own frost depth sets the real number and is not negotiable.