2026 cost guide · Denver, CO
How much does it cost to build a home addition in Denver, CO?
Typical range for an addition onto an existing home
$138,000 – $299,000
About $414/sq ft midrange across 500 sq ft. Denver, CO indexes at ×1.15 versus the national building-cost average — a city-level match in our cost index.
These figures come from the same estimating engine we use to price a real project — the local cost index for Denver, CO is baked in, not a national average with your city's name pasted on top. The number that matters is your project’s, though: finish level, site, and scope move it more than geography does. Get your exact home addition estimate →
Home addition cost by finish level in Denver, CO
Starter / builder-grade
$276/sq ft
$138,000
Midrange
$414/sq ft
$207,000
High-end / custom
$598/sq ft
$299,000
Based on 500 sq ft, a typical size for an addition onto an existing home. Your size and scope change the total — run your own numbers.
What goes into a home addition estimate
- •Site work, foundation & structure — the parts you never see but pay for first
- •Framing, roofing & the weather-tight shell
- •Mechanical, electrical & plumbing systems
- •Interior finishes — the single biggest swing in the whole budget
- •Permits, plan review & local fees
- •General conditions, contractor overhead & contingency
Get your exact Denver, CO estimate
Line-by-line costs for your specific project + a builder-ready brief. Free — no account, no card to see your number.
Estimate my home addition →Denver, CO home addition cost — FAQ
How much does it cost to build a home addition in Denver, CO?
A typical an addition onto an existing home in Denver, CO runs about $138,000 to $299,000 — roughly $276–$598 per square foot across 500 sq ft. Denver, CO indexes at ×1.15 versus the national building-cost average — a city-level match in our cost index.
What is the cost per square foot to build a home addition in Denver, CO?
Expect about $276/sq ft at a starter finish level, $414/sq ft midrange, and $598/sq ft for high-end custom work. Your exact rate depends on finish level, site conditions, and design complexity.
What drives the price up or down?
Finish level is the biggest lever, followed by site and access, structural complexity, and (for a remodel or addition) how much of the existing structure you keep. Local permit fees and labor availability move the total as well.
How do I get an exact estimate for my project?
Answer a few questions about your project and get a free, itemized estimate — line by line, with a builder-ready brief — in a few minutes. No account or payment required to see your number.
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Estimates are engine-generated planning figures for Denver, CO, not a quote. Actual pricing depends on your design, site, and builder. All cost guides.