Most deck pricing online quotes materials only — then the real bids land at double. Here's the honest math, using manufacturer material data plus what installation actually adds — and further down, a real bid broken into line items so you can see where every dollar goes.
Step 1 — Materials
Composite decking boards (Deckorators, Trex, TimberTech) run roughly $8–14 per sq ft for the boards themselves. Add the substructure (pressure-treated framing, footings, hardware) and railing, and all-in materials land around $20–30 per sq ft for a typical composite deck.
Step 2 — Add 50–100% for installation
Industry-wide, labor runs 50–60% of a finished deck's total cost — professional installation adds $15–35 per sq ft on top of materials. The rule of thumb: take your materials number and add 50–100%. A $12,000 materials list is a $18,000–24,000 finished deck. Height, slope, access, and design complexity decide which end you land on.
What that means by deck size
Installed composite, single level, with railing — national data; Front Range labor tends toward the upper half.
For calibration: the 2025 Zonda Cost vs Value report puts the national-average 16×20 composite deck addition at about $25,000 — and wood at about $18,000.
What your budget builds
Numbers anchor better with pictures. Real Haka projects, typical of what each range delivers in the Denver metro:
Ranges bracket what projects of each shape typically land at — every yard prices differently. The calculator gives your number; the portfolio shows what it looks like.
…and by material
Size sets the scale; the surface you choose sets the rate. Typical installed ranges per square foot, Denver metro:
Same substructure under all of them — the framing doesn't care what you walk on, which is why the cheap surface only saves you the board delta, not half the deck. Full comparison in the materials guide.
The three multipliers bids get judged on
These stack, and they're why two 320 sq ft decks can be $14,000 and $27,000 without either builder being wrong. An elevated deck is taller posts, engineered footings, railing at height, and staging — real structure, not margin. If a bid for a walk-out matches a bid for a ground-level deck, one of them misread the job.
A real bid, line by line
Here's what an itemized quote for a common project actually looks like — replacing a worn-out 16×20 wood deck with capped composite, mid-height, 36 lin ft of aluminum railing, four steps:
Landing right in the middle of the 16×20 installed range once tear-out is counted. Yours will differ — the point is the shape: if a bid can't be broken into lines like these, you can't compare it to anything.
The add-ons bids include (and calculators don't)
The big add-ons
Covers and kitchens are engineered structures with their own permits — priced per project, not per square foot. They're also the classic phase-two items: build the deck framed to accept them now, add them next season.
The ten-year math
Wood wins the day-one bid and loses the decade. A 320 sq ft pressure-treated deck at roughly $9,000 wants cleaning and re-staining every other year — $400–900 each round if you hire it out — plus board and fastener repairs as UV and freeze-thaw do their work. Call it $3,000–5,000 over ten years, on a surface that's aging anyway. The same deck in capped composite at $16,000 needs soap, water, and nothing else, with 25–50 year fade-and-stain warranties. The gap narrows to a few thousand dollars over a decade — and past year ten, composite is simply ahead.
How to read a bid — the red flags
Honest ways to bring the number down
Keep the footprint a simple rectangle — corners and angles cost framing hours. Stay low if the yard allows it; height is the biggest multiplier on the list. Put the premium railing on the view side and standard aluminum everywhere else. Pick stock colors (special-order boards add cost and weeks). Phase the pergola or kitchen to next year on framing that's ready for them. And time it right — signing in the off-season buys schedule flexibility and a spring deck, as our timing guide lays out. What doesn't save money: skipping the permit, undersizing footings, or reusing framing nobody inspected — re-decking over sound framing is the legitimate version of that shortcut.