how much does a 16x20 deck cost in Illinois?

A 320 sq ft deck runs roughly $9,000-$14,000 in pressure-treated, $12,000-$20,000 in cedar, and $16,000-$29,000 in composite, depending on height, railing style and stairs.

why are second-story decks more expensive?

Taller posts, more bracing, deeper footings, longer stair runs and more labor at height. Expect roughly 20-35% over the same deck at ground level.

does the permit cost extra?

Township permit fees vary and are folded into our quote — we pull the permit and schedule inspections so you don't handle any of it.

is composite worth the extra money?

If you're staying in the house, usually yes. You pay more upfront and then stop spending time and money on staining. If you're selling in a couple of years, pressure-treated or cedar often makes more sense.

2026 Cost Guide

how much does a deck cost in illinois?

Straight numbers from a builder, not a national average. This is what decks cost in Naperville and the surrounding Chicago suburbs right now.

Try the cost calculator or call (630) 780-4040

the short answer

Most new decks in this market land between $8,000 and $30,000. The two things that decide where you fall are square footage and decking material. Height off the ground and railing style come next.

cost by decking material

material	per sq ft installed	typical project	upkeep
pressure-treated pine	$25 – $45	$6,000 – $14,000	stain every 1-2 years
cedar	$35 – $65	$9,000 – $20,000	clean & seal every 2-3 years
composite (Trex, TimberTech)	$45 – $90	$13,000 – $30,000	wash occasionally

Typical project assumes a 250-350 sq ft deck with railing and one stair flight. Going composite? Our composite deck cost guide breaks down Trex and TimberTech pricing by tier and deck size.

what moves the number

size — the single biggest factor; cost scales almost linearly with square footage
height — a second-story deck adds roughly 20-35% over the same deck at grade
railing — wood is cheapest; cable and aluminum can add thousands across a long perimeter
stairs — every flight adds framing, treads and labor; landings add more
site access & grade — tight side yards and slopes add labor and footing depth
extras — lighting, built-in benches, pergolas, privacy screens and skirting

where homeowners overspend

Two places, over and over: buying a premium composite line when a mid-tier line performs identically at your deck's exposure, and oversizing. A well-planned 300 sq ft deck gets used more than a sprawling 500 sq ft one, and costs a third less.

The other cost people don't see coming is the change order. Our quotes don't drift — the price we quote is the price you pay.

questions we get

how much does a 16x20 deck cost in Illinois?: A 320 sq ft deck runs roughly $9,000-$14,000 in pressure-treated, $12,000-$20,000 in cedar, and $16,000-$29,000 in composite, depending on height, railing style and stairs.
why are second-story decks more expensive?: Taller posts, more bracing, deeper footings, longer stair runs and more labor at height. Expect roughly 20-35% over the same deck at ground level.
does the permit cost extra?: Township permit fees vary and are folded into our quote — we pull the permit and schedule inspections so you don't handle any of it.
is composite worth the extra money?: If you're staying in the house, usually yes. You pay more upfront and then stop spending time and money on staining. If you're selling in a couple of years, pressure-treated or cedar often makes more sense.

Free, no-obligation estimate — response within one business day.

(630) 780-4040

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