How Much Does an ADU Cost in Denver in 2026?

Planning-level pricing guide by ADUWizard.com
Updated for 2026 budgeting

Denver spent a decade approving ADUs one neighborhood at a time, and then in December 2024 it stopped pretending that made sense. A citywide zoning text amendment put attached and detached ADUs on the table in every residential district at once. If you were waiting for your block to get rezoned, the wait is over.

That single change is why I tell Denver homeowners to budget seriously now instead of someday. The rules got simpler, owner-occupancy is gone, and the city even runs pre-approved plans in West Denver. The one thing that did not get cheaper is the build itself, because Front Range labor and a frost-depth foundation do not care how friendly the zoning got.

Quick disclaimer: This is a budgeting guide, not a quote or legal advice. Denver’s per-lot rules on size, height, and setbacks vary by zone district, so confirm your specific lot with the Denver Zoning Code before you draw anything. Use these ranges to compare bids, not as a price.

What Changed in Denver in 2025

The citywide amendment aligned Denver with Colorado’s statewide ADU law, HB24-1152, which forces larger Front Range cities onto an administrative approval path and bans permanent owner-occupancy requirements. In plain terms: you no longer have to live on the property to build or rent the unit, and the city cannot make you add parking in most cases.

Two Denver-specific rules still shape the budget. Detached units have to sit in the rear 35% of the lot, which decides where your utilities run and how much trenching you buy. And Denver requires a licensed contractor to pull the permit, so the owner-builder route that trims cost in some states is off the table here.

Denver ADU Cost in 2026 (by Type)

Type	Typical size	All-in cost	What usually drives it
Garage conversion	350–600 sf	$100k–$150k	slab, egress, panel, alley access
Basement / interior	500–900 sf	$100k–$180k	egress windows, headroom, moisture
Attached ADU / addition	500–900 sf	$180k–$320k	tie-ins, roof, MEP
Detached new-build	500–1,000 sf	$350k–$500k	foundation, separate taps, rear-35% siting
Prefab / modular installed	490–800 sf	$245k–$320k	crane, foundation, hookups

All-in cost per square foot lands around $390–$500 for a detached new-build, which puts Denver above the Colorado Springs market and a little below Boulder.

Denver ADU Cost by Size

Size	Conversion	Detached
400–500 sf (studio)	$100k–$150k	$245k–$350k
600–750 sf (1-bed)	$130k–$180k	$330k–$430k
800–1,000 sf (2-bed)	$160k–$220k	$400k–$500k

The West Denver Pre-Approved Plans

Here is the Denver detail I wish every city copied. The West Denver Single Family Plus ADU program offers a set of pre-designed, pre-approved detached plans, from studios up to three-bedroom layouts, with expedited review and reduced fees. The city added modular options in late 2025.

A vetted plan means the reviewer checks your site instead of re-litigating the whole design, which trims both soft cost and calendar time. My prediction: pre-approved plans quietly become the default path for cost-conscious Denver builds within a couple of years, because the alternative is paying an architect to reinvent a studio ADU that the city has already blessed.

The Denver Hidden Costs

Item	When it hits	Planning range
ADU System Development Charge (water/sewer)	detached, new service	~$2,055 (rising to ~$2,170 on 7/1/2026)
Panel / service upgrade	older homes, heat pumps	$3k–$12k
Utility trenching + separate taps	detached units	$8k–$25k
Frost-depth foundation	every detached build	baked in, but adds vs warm climates
Soft costs (design, plan check, licensed GC)	every project	$15k–$40k

The SDC gets a lot of attention because Denver publishes it, but honestly it is one of the smaller lines here. The bigger swing is the foundation and the utility runs, which is exactly why the rear-35% siting rule matters: the farther your unit sits from the existing service, the more trench you pay for.

Example Denver Budget: 750 sf Detached ADU (1-Bed)

Category	Budget
Design + engineering	$12,000–$25,000
Permits + SDC + fees	$6,000–$16,000
Sitework + utilities (taps, trenching)	$20,000–$45,000
Foundation + framing + envelope	$130,000–$200,000
MEP (heat pump, plumbing, electrical)	$40,000–$65,000
Interior finishes	$35,000–$70,000
Contingency	$25,000–$45,000
Total all-in	$330,000–$430,000

Denver ADU Permit Timeline

Plan on roughly 2–4 months from a complete submittal to permit for a straightforward unit, faster if you run zoning, building, and sewer review concurrently, and faster still on a pre-approved West Denver plan. Total project time, design through final inspection, usually lands in the 9-to-14 month range.

Where Denver Ranks in Colorado

By our Colorado ADU cost data, Denver sits in the middle of the state’s major markets: more expensive than Colorado Springs, which is the value play, and a step below Boulder, where small size caps push the per-square-foot cost up. What Denver has that neither of those offers is the pre-approved plan program, and for a lot of homeowners that is worth more than a slightly lower sticker price. The Data Hub tracks these ranges as they move.

FAQs (Denver)