How much do contractors charge per square foot for a deck?

Folklore says $30–$70+ per sq ft installed, wood to composite — but the spread is height, stairs, railing, and site, none of which per-foot pricing sees. Build the number from systems and it defends itself.

What's the most underestimated part of a deck bid?

Stairs and railing. A tall deck's stair run with matching rails can approach the labor of the main field — priced per rise and per linear foot, not absorbed into the deck's square footage.

How much does height change deck cost?

Substantially: taller posts and bracing, harder footing work, staging or fall protection, and slower everything. State a height factor in the quote instead of eating it.

Field guide

How Much to Charge to Build a Deck — the Systems Math, Worked

Deck pricing folklore is quoted per square foot and paid for in stairs. Here's the systems method on a real configuration, so the folklore's blind spots are visible in the arithmetic.

Worked example: 16×20 attached PT deck, 5 ft off grade, one stair run

Footings: 9 at frost depth, augered — 9 × $140 installed = $1,260.
Frame: 320 sq ft — ledger flashed, 2x10s at 16", doubled beam — materials $2,050, labor 34 hrs.
Surface: PT 5/4 straight lay +10% waste — materials $1,180, labor 16 hrs.
Railing: 44 lf baluster rail — materials $900, labor 13 hrs.
Stairs: 8 rises with rails — materials $340, labor 10 hrs. Note: 73 total labor hours and the stairs+rails are 23 of them — a third of the labor in 6% of the "square footage."
Labor: 73 hrs × $65 loaded = $4,745. Direct cost ≈ $10,475.
At 35% margin: ÷ 0.65 ≈ $16,100 — about $50/sq ft, arrived at honestly.

What the per-foot number can't see

Run the same deck at ground level with no rails and no stairs: direct cost drops by roughly a third, and $50/sq ft becomes gouging. Run it 9 feet up with two stair runs: $50 becomes charity. Height, rises, and rail feet are the price — square footage is just the field they attach to.

Quote the systems, keep the margin

FieldSquire drafts the systems from a narrated site walk at your saved rates, applies your margin privately (divide method — check yours on the free margin calculator), and delivers the signable PDF the same visit. The carpentry estimating app is free for 14 days.

Try it on a real job: FieldSquire's Solo plan is free for 14 days with no credit card — unlimited manual estimates and AI-assisted drafts you review line by line. Start the free trial or see the carpentry estimating app guide.