10×12 Deck Cost
A 10×12 deck (120 sqft) is the median small-deck size in the US — the most-permitted deck size for first-time builders. The calculator below is pre-loaded with these dimensions — change the state, finish tier, or scope to recalculate live.
How much does a 10×12 deck cost?
- PT installed
- $3,000–$4,800
- Mid composite
- $6,000–$9,600
- Per sqft
- $25–$140
How much a 10×12 deck costs by material
A 10×12 costs about $3,000–$4,800 in pressure-treated surface and $6,000–$9,600 in mid-range composite, installed. All-in at the calculator's default spec — railing, four steps, permit, contingency — the project runs near $15,800, or $131 per square foot. The interesting comparison is against the 10×10 next to it: 20 more square feet costs about $1,900, which is $95 per added foot against the smaller deck's $139 average. Twenty square feet is the cheapest upgrade on this page.
Premium composite or PVC (Trex Transcend, TimberTech AZEK) lands around $9,000–$13,200, and tropical hardwood like Ipe tops out near $10,800–$16,800. These are installed (material + labor) for a simple rectangle — an L-shape adds ~10%, a wraparound ~22%, and a tall or hard-to-access deck up to 40%. Regionally, the South runs about 8% under these national figures and the West Coast about 28% over.
Cost per square foot
Installed, that's about $25–$40/sq ft in pressure-treated, $50–$80/sq ft in mid-range composite, and up to $90–$140/sq ft in tropical hardwood.
Materials vs. labor
Labor runs $10–$20/sq ft — about $1,200–$2,400 on this 120 sq ft deck: roughly half a pressure-treated build, about a third of a composite one.
The calculator below itemizes a complete project — framing, footings, railing, stairs, permit, and contingency — so its total runs higher than the surface-and-labor bands above for the same size.
What fits on a 10×12 deck?
120 sq ft is the size that fits a table and a route past it. A six-seat rectangular table takes roughly 8′ × 3′6″ and needs about 2′6″ behind each chair to sit down, which lands almost exactly on the 10′ dimension and leaves the remaining 2′ as a walkway along the 12′ side. That is a genuinely usable deck rather than a landing — and it is the reason 10×12 turns up more than any other small size in permit records and plan books.
Under the 200 sq ft permit-exemption ceiling — but most jurisdictions still require a permit once the deck attaches to the house or sits over 30″ above grade.
Does a 10×12 deck add home value?
A new deck recovers roughly 65–75% of its cost at resale — on a 10×12 that is $1,950–$7,200 back into the appraisal, per Remodeling’s Cost vs. Value report. See the report.
Sources: IRC 2021 (structural + permit thresholds), RSMeans 2026-Q1 residential labor indices, HomeAdvisor / Angi 2026 material pricing, and Remodeling Cost vs. Value.
Dimensions
Plan-view length × width.
IRC R312 requires a 36″ guardrail above 30″.
120 sq ft · Mid composite · 1.22× labor · 1.10× complexity
Project advisories · IRC 2021
Guardrail included (deck 36″ off grade)
IRC R312IRC R312 mandates a 36″ guardrail on open edges when deck height exceeds 30″. 32 lf priced at Mid composite tier.
Building permit included in budget
IRC R105Northeast typical permit fee is in the budget. Most jurisdictions require a permit for decks > 200 sqft, > 30″ above grade, or attached to the house.
Hidden-fastener install premium baked in
Manufacturer specsMid composite uses hidden-fastener clip systems (Cortex / CamoClip / Trex Universal) — labor takes 25–30% longer than face-screwing PT. Already inside the tier's installed $/sqft band.
Cost breakdown
| Cost component | Share | Amount |
|---|---|---|
| Materials | 24% | $4,752 |
| Labor | 35% | $7,086 |
| Add-ons | 30% | $6,051 |
| Soft costs | 2% | $320 |
| Contingency | 9% | $1,821 |
| Total (high est.) | 100% | $20,030 |
Share of the high estimate. Switch tiers below to repaint the split.
National-median pricing (2026-Q1). Local prices vary ±15%. Materials line uses Mid composite tier; switch tiers to repaint the budget. Includes 10% contingency reserve on the high estimate.
Visualize your deck
Photoreal 3D · plan view · framing breakdown. Color matches your tier selection.
Project all-in
Same dimensions, different tier
tap to switchDIY savings
- Materials only: $4,752
- Estimated hours: 180 hr
- Skill required: advanced
Finance estimate
- Principal: $20,030
- Total interest: $4,332
- Estimate only — shop 3+ lenders.
Need exact board counts?
The Deck Material Calculator gives you a permit-ready bill of materials — every joist, hanger, fastener, and footing — validated against IRC 2021 span tables.
Estimates use 2026-Q1 national-median pricing (Home Advisor, Angi, RSMeans). Expect ±15% variance vs your local market. Always get 3 contractor bids before signing. This calculator is not a substitute for a licensed inspector or structural engineer.
Estimated material takeoff — 10×12
The framing and decking a 10×12 (120 sqft) deck needs — board, joist, beam, post, footing, and railing quantities computed from the dimensions at 16″ joist spacing with a 10% waste factor.
Estimated quantities for planning and budgeting — round up when ordering. Beam sizing, post spacing, and footing depth must follow your local code and a stamped plan (frost line, soil, and snow load vary by region per IRC 2021 / AWC DCA-6).
Cutting plan: how a 10×12 lands on stock lumber
12′ is the friendliest run length in decking. Both families stock it — pressure-treated, cedar, and every major composite line — so all 22 rows are single boards with no butt seams, no offcut, and no sistered joist to carry a seam. That is not true of the 10×10 beside it, where composite has to be bought at 12′ and cut back. If you are choosing between the two sizes and leaning composite, the 10×12 is materially cheaper per square foot of finished deck than the two-foot difference suggests.
Framing follows the same logic in the other direction: the 10 joists span 10′, cut from 10′ stock with nothing left over. Quantities come from the takeoff above; check the span itself with the joist span calculator.
What the 10×12 footprint means for framing
Joists still run the 10′ dimension here, so the framing is the same cheap arrangement as a 10×10: SPF 2×8 at 16″ on centre, inside the 11′1″ that IRC 2021 R507.6 allows, on one beam line and 4 footings. What changes is only length — 10 joists instead of 9, and 24 linear feet of beam instead of 20. Adding area along the beam is the cheapest direction to grow a deck, and this footprint is the clearest illustration of it. Check your exact joist setup with the joist span calculator and size the beams with the beam span calculator.
Sizing up or down? See how much a 10×10 deck costs (100 sqft) or how much a 12×12 deck costs (144 sqft).
Why 10×12 is the most-built small deck in the country
Three constraints happen to line up at this footprint. It is under the 200 sq ft that IRC 2021 R105.2 uses as its permit-exemption ceiling. The 10′ joist run is inside what 2×8 SPF spans at 16″ on centre, so the framing needs no intermediate beam. And the 12′ board run matches a stock length in every decking material sold, so nothing is cut to waste.
Push any one dimension out by two feet and one of those three breaks: 12×12 steps the joists up to 2×10, 10×14 puts the boards on 16′ stock with 2′ cut off every row, and anything past 200 sq ft brings the permit back in most places.
That is worth knowing when a contractor offers to "make it a bit bigger while we're here". Sometimes that is nearly free — along the 12′ beam line it is. In the other direction it quietly changes the lumber schedule.
What a square foot really costs at 120 sq ft
The rate below is this page's own calculator run at its default spec, and the third card is the one worth reading: it prices the square feet a 10×12 adds over the next size down, which is almost never the same as the average rate.
Figures come from this page's own calculator engine at its default spec (36″ ledger deck, premium composite, railing, 4 steps, permit included, national labor) — change any input above and the totals move with it.
FAQ — 10×12 deck
How much does a 10×12 deck cost?
A 10×12 is 120 sq ft. The decking surface runs about $3,000–$4,800 installed in pressure-treated and $6,000–$9,600 in mid-range composite at national-average 2026-Q1 rates. Budget against the complete project rather than the surface: with railing, four steps, the permit and a 10% contingency, the calculator's default spec puts a 10×12 near $15,800, which is $131 per square foot. Labour alone is $10–$20 per square foot, so $1,200–$2,400 of that total is the crew. Regionally the spread is wide — about 8% below these figures in the South and 28% above on the West Coast — because labour, not material, is what varies by market. Materials are close to national retail wherever you build.
Is a 10×12 deck worth the extra cost over a 10×10?
By the arithmetic, yes, and it is the best-value step on the entire size ladder. Running the same calculator spec on both footprints, a 10×10 comes to about $13,900 and a 10×12 to about $15,800. That is roughly $1,900 for 20 more square feet, or about $95 per added foot, against the smaller deck's $139 average rate. The reason is that the extra area is added along the beam line, so it needs no deeper joist, no extra beam and no additional footings — just longer members and two more rows of boards. It also removes the composite waste problem: a 12-foot run matches stock in every decking material, while a 10-foot run does not in composite.
What size joists does a 10×12 deck need?
SPF 2×8 at 16 inches on centre, in the standard ledger-and-beam layout. Joists span the short dimension, so on a 10×12 they run 10 feet from the ledger to a single beam at the outer edge. The IRC 2021 R507.6 span table rates 2×8 SPF at 16 inches on centre to 10 feet 5 inches, so a 10-foot run passes with five inches to spare and needs no intermediate support. That gives 10 joists, one beam line, 24 linear feet of beam and 4 footings for the whole deck. Note how narrow the margin is: extend that same direction to 12 feet and the 2×8 no longer qualifies, and the entire joist schedule steps up to 2×10.
How many boards does a 10×12 deck take?
Twenty-two rows of 12-foot boards, and nothing is cut. The 5½-inch face plus a ⅛-inch gap gives 5.625 inches per row, so a 10-foot width needs ceil(120 ÷ 5.625) = 22 rows, each covering the 12-foot dimension. Twelve feet is a stock length in pressure-treated, cedar and every major composite line, so all 22 rows are single boards with no butt seams, no offcut and no sistered joist to carry a seam. That is unusual — most footprints waste something — and it is worth weighing if you are choosing between this size and a 10×14, which would put every row on 16-foot stock and cut two feet off each one.
Do I need a permit for a 10×12 deck?
Usually yes if it attaches to the house, and possibly not if it does not. At 120 sq ft a 10×12 is under the 200 sq ft ceiling IRC 2021 R105.2 uses for its permit exemption, but the exemption also requires the deck to sit no more than 30 inches above grade, to be freestanding rather than ledger-attached, and not to serve a required exit door. Most 10×12 decks are built off a back door on a ledger, which fails two of those tests. Even where a permit is not required, a guard is: IRC 2021 R312 mandates a 36-inch guardrail on open edges once the walking surface is more than 30 inches above the ground, permit or no permit.
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