10×10 Deck Cost

A 10×10 deck is 100 sq ft, which puts the decking surface at roughly $2,500–$4,000 installed in pressure-treated wood and $5,000–$8,000 in mid-range composite at 2026-Q1 national-average rates. The number to budget against is larger: a complete permitted project with railing, a short stair flight, the permit fee and a 10% contingency runs about $13,900 on this footprint, or $139 per square foot. That rate is the highest of any deck size on this site, and it is not because small decks are built to a higher standard — it is because roughly 36% of that budget is permit, stairs and railing, costs that barely change when the deck gets bigger. If the yard allows a larger deck at all, the extra square footage is the cheapest part of the project.

Often not, and this is one of the few deck sizes where the exemption is realistically within reach. IRC 2021 R105.2 allows a jurisdiction to exempt a deck that is not more than 200 sq ft, sits no more than 30 inches above grade at any point, is freestanding rather than attached to the house with a ledger, and does not serve a required exit door. A 10×10 is 100 sq ft, so it clears the area test with room to spare, and a ground-level freestanding build satisfies the rest. The catch is that R105.2 is permissive, not mandatory — plenty of jurisdictions have not adopted it, and some add their own conditions. One call to the building department settles it, and a permit is the cheapest line on the whole project compared with discovering at resale that the deck was never inspected.

It costs more than the price-per-square-foot tables suggest, for a reason specific to this size. Composite decking is extruded in 12-foot, 16-foot and 20-foot lengths only — Trex, TimberTech and Fiberon all publish the same three — while pressure-treated and cedar are sold in 10-foot lengths as well. A 10-foot board run therefore means buying 12-foot composite and cutting two feet off every one of the 22 rows: 44 feet of offcut, about 17% of the decking spend, thrown away before the first screw goes in. Wood has no such waste at this size. If you want composite on a small deck, designing at 10×12 instead removes the waste entirely and adds usable floor, which is usually the better trade than paying for boards you bin.

Twenty-two rows. Standard 5/4×6 or 2×6 decking has a 5½-inch face laid with a ⅛-inch gap, so each row covers 5.625 inches and a 10-foot width takes ceil(120 ÷ 5.625) = 22 rows. In pressure-treated that is 22 boards at 10 feet with no cutting at all. In composite it is 22 boards at 12 feet, of which 44 feet ends up as offcut. Add 5–7% on top if you plan a diagonal layout or a picture-frame border, and order the whole quantity in one delivery — a deck short by one or two boards means a second delivery fee that can exceed the value of the boards themselves, and on composite it risks a different colour lot.

This is the size where a competent DIY build is most realistic. The framing is as simple as decks get: joists run the 10-foot dimension, which SPF 2×8 at 16 inches on centre spans with five inches of margin against the 10 feet 5 inches allowed in the IRC 2021 R507.6 table, so there is no intermediate beam to set. The whole deck lands on 9 joists, one beam line and 4 footings. Labour is roughly half the installed cost of a pressure-treated build, so doing it yourself saves in the region of $1,000–$2,000 on this footprint. The two details worth not improvising are the footing depth, which must reach below the local frost line, and the ledger connection if the deck attaches to the house — that connection is the most common structural failure on owner-built decks.