Deck Building Cost in Boulder, CO (2026)
Updated October 2026 · Boulder, CO · index 1.03
How much does it cost to build a deck in Boulder? For a 300 sq ft deck with pressure-treated wood, homeowners in Boulder, CO 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 Boulder runs 3% above the U.S. average: construction labor in the Boulder area runs 2% above the national mean, materials 3% above. The same job averages $11,300 nationally and about $11,400 at the Colorado statewide index.
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Deck building price in Boulder by decking material
What a 300 sq ft deck costs in Boulder 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 Boulder is pressure-treated wood, at about $11,600; capped composite averages $13,900, 1.2 times as much.
Cost to build a deck in Boulder by size
With pressure-treated wood, priced for Boulder, CO:
| 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 Boulder 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 Boulder's index of 1.03; permit fees are not scaled.
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What affects deck building prices in Boulder
Labor and materials in Boulder
Construction wages in the Boulder area run 2% above the U.S. mean (BLS, May 2025), and materials in its ZIP codes price 3% above the national average. Together they give Boulder a construction cost index of 1.03.
Where Boulder sits in Colorado
Boulder is the 4th most expensive of the 7 Colorado cities in our index, against a statewide index of 1.01. Denver is the dearest at 1.06; Pueblo is the least expensive at 0.96.
Against the rest of the country
Of the 306 U.S. cities in JobFlex's index, Boulder ranks 131st from the most expensive. The job that averages $11,600 here averages $11,300 at the national rate.
Frost depth in Colorado
Deck footings go below the frost line, or they heave by the second spring. The typical code frost depth in Colorado is about 36 in. — deep holes, more concrete and more digging time than in the South. Your building department sets the exact figure.
The deck code in Colorado
There is no statewide code; decks follow the International Residential Code as the cities and counties of Colorado adopt it (Denver: 2025 Denver Building Code on the 2024 IRC; Jefferson County: 2024 IRC; Pikes Peak Regional and Arapahoe 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 Colorado
Most used on decks in the Mountain states: capped composite, then treated hem-fir or fir 2x6, then cedar.
Sales tax in Colorado
Colorado's base state sales tax is 2.9%, and cities and counties can add their own. How it applies to a home-improvement contract varies, so ask whether a quote includes it. Prices on this page are before tax.
What a Boulder contractor will ask before quoting
- Reuse the frame or rebuild?
- Height, railing style and stairs
- Board brand and color
Deck building cost in other Colorado cities
A 300 sq ft deck with pressure-treated wood averages $11,600 in Boulder; $11,700 in Lakewood, $11,000 in Colorado Springs, $11,700 in Aurora.
| City | Average · range |
|---|---|
| Lakewood, CO1% more | $11,700$8,100 – $15,300 |
| Colorado Springs, CO5% less | $11,000$7,650 – $14,400 |
| Aurora, CO1% more | $11,700$8,100 – $15,300 |
| Fort Collins, CO4% less | $11,100$7,700 – $14,600 |
| Denver, CO3% more | $11,900$8,250 – $15,600 |
| Pueblo, CO7% less | $10,800$7,450 – $14,100 |
deck building price in Boulder: questions
How much does it cost to build a deck in Boulder, CO?
About $11,600 for a 300 sq ft deck with pressure-treated wood, and most Boulder 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 Boulder?
$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 Boulder?
$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 Boulder?
Yes — a new deck needs a permit nearly everywhere, Boulder included. In Colorado, decks follow the International Residential Code as the cities and counties of Colorado adopt it (Denver: 2025 Denver Building Code on the 2024 IRC; Jefferson County: 2024 IRC; Pikes Peak Regional and Arapahoe County: 2021 IRC). The prices on this page carry $380–$1,150 for plans, permit and layout.
Does the price include sales tax in Colorado?
No. The prices here are before tax; Colorado's base state rate is 2.9%, plus any local rate.
What decking do people choose in Colorado?
Most used on decks in the Mountain states: capped composite, then treated hem-fir or fir 2x6, then cedar.
Other home projects in Boulder
Deck building cost in Colorado
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 Boulder'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 Boulder, each on its own base: RSMeans residential 0.87, HUD 0.95, Craftsman 1.05. Treat any city figure as about ±5%; a contractor's quote for your house is the number to plan with.
Contractors in Boulder 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