Deck cost by material (per square foot, installed)
Material is the single biggest cost driver in a deck, and in Northern Illinois it's also a genuine decision — composite isn't automatically the smarter buy, and we don't push it by default. Here's the honest range for each, installed, in our market. These are the same numbers we quote from; the exact figure lands after we've seen your yard, because condition, height, and access all move it.
| Material | Installed cost / sq ft | Maintenance | Lifespan | Best for |
|---|---|---|---|---|
| Pressure-treated wood | $15–$30 | High — clean & refinish every few years | 15–20 years with upkeep | Budget builds; selling within 3–5 years |
| Cedar | Mid-range (between PT and composite) | Moderate–high — real-wood finish to keep up | 15–25 years with upkeep | Homeowners who want real-wood grain and warmth |
| Composite (Trex/TimberTech/AZEK/Fiberon) | $30–$55 (premium/elevated ~$60–$70) | Lowest — occasional cleaning, no refinishing | 25–50 years, holds color in full sun | Staying 10+ years; lowest long-term hassle |
Pressure-treated is the lowest upfront cost and the honest choice if you're on a budget or planning to sell soon — no reason to sink composite money into a deck the next owner inherits. The trade-off is maintenance: real wood needs cleaning and refinishing every couple of years to fend off Illinois sun and moisture. Cedar sits in the middle, naturally rot-resistant and beautiful, but it's still a real-wood finish to keep up and it weathers to gray if you let it. Composite is the highest upfront number, and the premium and elevated lines can reach roughly $60–$70 per square foot, but you never refinish it and it holds color far better in full sun. Over a long enough horizon, the maintenance you skip usually makes composite the lower total cost.
Deck cost by size
The fastest way to sanity-check a budget is square footage times the per-foot range above. Below are three common deck sizes with rough installed totals in each material. Treat these as planning ranges, not quotes — a real number comes from the on-site consult, where height, railings, stairs, and site conditions all factor in.
| Deck size | Square feet | Pressure-treated | Cedar (approx.) | Composite |
|---|---|---|---|---|
| 12 × 16 | 192 sq ft | $2,900–$5,800 | $4,800–$7,700 | $5,800–$10,600 |
| 16 × 20 | 320 sq ft | $4,800–$9,600 | $8,000–$12,800 | $9,600–$17,600 |
| 20 × 24 | 480 sq ft | $7,200–$14,400 | $12,000–$19,200 | $14,400–$26,400 |
Two things move these totals up. An elevated or second-story deck costs more per square foot than a ground-level one, because it needs taller posts, more structure, and more labor. And premium composite lines (capped PVC like AZEK, or the top Trex and TimberTech series) can push the composite column toward that $60–$70 figure. A simple, ground-level pressure-treated deck sits at the low end; a tall composite build with a designer railing sits at the high end.
What's in the price — the line items
A deck total isn't just decking boards. Here's what a fixed-bid deck price actually covers, so you can read a proposal and know nothing's hidden:
- Footings & concrete. Holes dug and poured to the 42-inch frost depth code requires here. Deeper footings mean more digging, more concrete, and more labor than warm-climate builds — a real Illinois cost driver.
- Permit & inspections. The permit fee (typically a few hundred dollars, varying by town and project value) plus the two required inspections. On our builds this is handled for you — see the McHenry County permit guide for how that works town by town.
- Framing & hardware. Posts, beams, joists, the ledger connection and flashing, joist hangers, and structural fasteners. This is the skeleton you never see and can't cheap out on.
- Decking. The boards themselves — the material choice that swings the total most.
- Railings. Composite, aluminum, and cable railing systems each carry different costs; railing is often priced by the linear foot, so more perimeter means more railing cost.
- Stairs. Each set of stairs adds framing, treads, and a railing, so a deck with multiple stair runs costs more than one with a single set.
- Lighting & extras. Built-in stair and railing lighting, benches, planters, and multi-level tiers all add to scope.
Why decks cost more to build in Illinois
National cost calculators lowball Northern Illinois for a few concrete reasons, and it's worth understanding them before you compare bids.
Frost footings add real cost
That 42-inch minimum footing depth isn't free. Compared to a deck in a warm state where footings might go 12–18 inches, an Illinois deck needs deeper holes, more concrete, and more labor per footing. It's not a place to cut — footings that stop short of the frost line heave every winter and rack the deck — but it does mean our baseline is higher than a national average suggests.
A five-month build season
Deck building and staining season in Northern Illinois runs roughly late April through early October — about five months. That compressed window means demand stacks into a short stretch, and the summer calendar fills fast. Homeowners who book their consult in late winter or early spring get the summer dates; the ones who wait until June are competing for what's left.
Labor and code
Illinois labor rates and the code requirements here — proper ledger flashing, structural fasteners, guardrail heights, permitted inspections — all sit above what a bare-minimum build in a cheaper market would run. That's the cost of a deck that passes inspection and stands straight for decades, and it's exactly what a suspiciously cheap bid is leaving out.
Composite vs. wood — the total-cost-of-ownership math
The sticker price tells you half the story. The honest way to compare composite and wood is over the years you'll own the deck.
A pressure-treated deck is cheapest to build, but you'll clean and refinish it every couple of years. Refinishing runs $2.75–$4.50 per square foot each time — so on a 320-square-foot deck, that's several hundred to over a thousand dollars every two to three years, plus your weekends. Over 20 years, those recoats add up to real money on top of the build.
A composite deck costs more upfront, sometimes double the pressure-treated number, but you never refinish it — just wash it occasionally. If you're staying in the home 10 or more years, the maintenance you skip usually closes the gap and then some, and you get a deck that holds its color in full sun instead of graying out. If you're selling within a few years, the math flips: pressure-treated is the smart, honest buy, and there's no reason to hand the next owner a premium deck on your dime.
There's no universally right answer — there's the right answer for how long you're staying and what you want to spend maintaining it. We'll give you the straight recommendation on the consult, not an upsell.
How our deck estimates work
Every deck we build is fixed-bid, not hourly. We come out for a free on-site design consult, look at your yard, talk through size, material, height, and railing, and then put one firm number in writing — with material, railing, and lighting allowances spelled out. No hourly meter, no vague "we'll see when we get into it," and no surprise change orders halfway through. The ranges on this page are how to think about the budget before we ever come out; the fixed bid is the number you actually build to.
Ready to price your project? Start with a free deck design consult, and if a permit's on your mind, our McHenry County deck permit guide covers exactly what your town requires.