Deck Building Cost in Wilmington, DE (2026)
Updated October 2026 · Wilmington, DE · index 1.03
How much does it cost to build a deck in Wilmington? For a 300 sq ft deck with pressure-treated wood, homeowners in Wilmington, DE pay about $11,600 on average, and most quotes land between $8,000 and $15,200 — $27 to $51 per sq ft. The price covers plans and the permit, footings, a framed and flashed structure, the deck boards, railing, one set of stairs, fascia and cleanup.
The deck building price in Wilmington runs 3% above the U.S. average: construction labor in the Wilmington area runs 4% above the national mean, materials sit at the national level. The same job averages $11,300 nationally and about $11,000 at the Delaware statewide index.
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Deck building price in Wilmington by decking material
What a 300 sq ft deck costs in Wilmington with each decking material, installed:
| Option | Average · range |
|---|---|
| Pressure-treated woodtreated pine or fir boards, stained and sealed$39 per sq ft | $11,600$8,000 – $15,200 |
| Capped compositehidden fasteners and a picture-frame border$46 per sq ft | $13,900$9,900 – $17,900 |
The least expensive option in Wilmington is pressure-treated wood, at about $11,600; capped composite averages $13,900, 1.2 times as much.
Cost to build a deck in Wilmington by size
With pressure-treated wood, priced for Wilmington, DE:
| Size | Average · range |
|---|---|
| A 200 sq ft deck$42 per sq ft | $8,350$5,700 – $11,000 |
| A 300 sq ft deck$39 per sq ft | $11,600$8,000 – $15,200 |
| A 400 sq ft deck$37 per sq ft | $14,800$10,300 – $19,400 |
Some costs stay the same whatever the size — plans, permit and layout, one set of stairs (4 steps), final inspection and cleanup — so a bigger job costs less per unit: $37 per sq ft for a 400 sq ft deck against $42 for a 200 sq ft deck.
What a deck building in Wilmington includes
Line by line, the $11,600 average for a 300 sq ft deck breaks down like this: 47% labor, 53% materials and equipment.
| Line | Low – high |
|---|---|
| Plans, permit and layout | $380 – $1,150 |
| Ground prep, fabric and gravel | $230 – $570 |
| Footings below the frost line | $430 – $850 |
| Flashed ledger on the house | $260 – $500 |
| 6x6 posts | $280 – $570 |
| Beams | $260 – $500 |
| Joist framing with hangers | $1,500 – $2,500 |
| Deck boards | $1,350 – $2,050 |
| One set of stairs (4 steps) | $530 – $1,050 |
| Railing | $1,950 – $3,350 |
| Fascia and skirting | $370 – $890 |
| Final inspection and cleanup | $150 – $380 |
| Stain and seal, two coats | $340 – $800 |
Each line is the price book's U.S. rate for that step, scaled by 0.74 to the installed price published sources give for the whole job (see how these prices are built), times Wilmington's index of 1.03; permit fees are not scaled.
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What affects deck building prices in Wilmington
Labor and materials in Wilmington
Construction wages in the Wilmington metro run 11% above the U.S. mean (BLS, May 2025), and specialty-contractor pay in the city's county moves that down by 6%, to 4% above the national mean. Materials in the area's ZIP codes price right at the national average. Together they give Wilmington a construction cost index of 1.03.
Where Wilmington sits in Delaware
Wilmington is the most expensive of the 2 Delaware cities in our index, against a statewide index of 0.98. Dover is the least expensive at 0.94.
Against the rest of the country
Of the 306 U.S. cities in JobFlex's index, Wilmington ranks 131st from the most expensive. The job that averages $11,600 here averages $11,300 at the national rate.
Frost depth in Delaware
Deck footings go below the frost line, or they heave by the second spring. The typical code frost depth in Delaware is about 24 in.. Your building department sets the exact figure.
The deck code in Delaware
There is no statewide code; decks follow the International Residential Code as the cities and counties of Delaware adopt it (New Castle County: 2021 IRC since 2024 (the 2024 IRC reported from 2026); Kent County: 2018 IRC; Sussex County: 2021 IRC). Guards are required at 36 in. where the deck is more than 30 in. up, and stair risers can be up to 7.75 in.
What decks are built of in Delaware
Most used on decks in the South Atlantic states: treated pine, then capped composite, then cedar.
Sales tax in Delaware
Delaware has no state sales tax. Prices on this page are before any tax.
What a Wilmington contractor will ask before quoting
- Reuse the frame or rebuild?
- Height, railing style and stairs
- Board brand and color
Deck building cost in other Delaware cities
A 300 sq ft deck with pressure-treated wood averages $11,600 in Wilmington; $10,600 in Dover.
| City | Average · range |
|---|---|
| Dover, DE9% less | $10,600$7,300 – $13,800 |
deck building price in Wilmington: questions
How much does it cost to build a deck in Wilmington, DE?
About $11,600 for a 300 sq ft deck with pressure-treated wood, and most Wilmington quotes fall between $8,000 and $15,200. That is 3% above the U.S. average, where the same job averages $11,300.
What is the deck price per square foot in Wilmington?
$27 to $51 per sq ft, about $39 on average with pressure-treated wood. Smaller jobs cost more per unit, because the fixed costs are spread over less.
How much is a 400 sq ft deck in Wilmington?
$10,300 to $19,400, about $14,800 on average, with pressure-treated wood — $37 per sq ft.
Do you need a permit for deck building in Wilmington?
Yes — a new deck needs a permit nearly everywhere, Wilmington included. In Delaware, decks follow the International Residential Code as the cities and counties of Delaware adopt it (New Castle County: 2021 IRC since 2024 (the 2024 IRC reported from 2026); Kent County: 2018 IRC; Sussex County: 2021 IRC). The prices on this page carry $380–$1,150 for plans, permit and layout.
Does the price include sales tax in Delaware?
No tax is included, and Delaware has no state sales tax.
What decking do people choose in Delaware?
Most used on decks in the South Atlantic states: treated pine, then capped composite, then cedar.
Other home projects in Wilmington
Deck building cost in Delaware
How these prices are built
Every price on this page comes from JobFlex's contractor price book: what a homeowner pays a licensed contractor for each step of the job, as a U.S. national average per unit, with the contractor's overhead and profit included and sales tax left out. The deck building is priced step by step, then multiplied by Wilmington's construction cost index of 1.03.
Where the price book's steps for an option add up to more than 20% over the installed price a published source gives for the whole job, every step but a permit fee is scaled down to the middle of that range: pressure-treated wood × 0.74 (HomeGuide 2026: $25–$50 per sq ft); capped composite × 0.80 (Ergeon 2026: $30–$60 per sq ft).
The index weighs local construction wages (BLS Occupational Employment and Wage Statistics, May 2025) at 60% and the area's material prices (Craftsman ZIP-area factors) at 40%. Published indices for Wilmington, each on its own base: HUD 1.08, Craftsman 1.03. Treat any city figure as about ±5%; a contractor's quote for your house is the number to plan with.
Contractors in Wilmington build quotes like these with JobFlex's Deck Studio.
- HomeGuide 2026: pressure-treated deck $25-$50/sqft installed, labor $15-$30/sqft
- Ergeon 2026: composite deck $30-$60/sqft installed
- HomeGuide 2026: composite railing $25-$60/lf, aluminum $50-$200/lf installed