How to Choose an ADU Contractor in Colorado (Questions to Ask)
How to hire an ADU contractor in Colorado, the questions to ask, the red flags to avoid, how licensing works here, and modular versus site-built compared.
Aurora’s real rules, taxes and rents — read from the codified ordinance, every figure sourced and dated. Here: a HUD benchmark rent of $1,754/mo for a 1-bed. Run your own numbers below, free.
Read from the Aurora Unified Development Ordinance itself — the operative legal text, not a website summary. Aurora is an HB24-1152 subject jurisdiction: since June 30, 2025, state law requires it to allow an ADU wherever it allows a single-family home, with administrative approval — the local standards below still apply. Aurora Planning told us in October 2026 that it applies UDO §146-3.3.6.G to new ADUs: a 650 sq ft maximum, Conditional Use approval for every ADU, and ADUs only in the zone districts that permit them. That differs from the administrative approval state law calls for. The state requirement still applies, and how the two fit together is unresolved, so confirm the current approval process for your parcel with Aurora Planning.
| Maximum ADU size | 650 sq ftverified September 2026Aurora Unified Development Ordinance §146-3.3.6.G.1.hthe ordinance text"h. The maximum size of an accessory dwelling unit is 650 square feet." |
| Height limit | 24 ft (the code also states a detached ADU may not exceed the main home's height)verified September 2026Aurora Unified Development Ordinance §146-3.3.6.G.1.ithe ordinance text"i. The accessory dwelling shall not exceed the height of the principal dwelling or 24 feet." ... "p. The accessory dwelling unit shall not exceed 24 feet in height, regardless of the height of the primary dwelling structure." |
| Owner occupancy | Yes — the owner must live in either the main home or the ADUverified September 2026Note: Aurora is an HB24-1152 subject jurisdiction. Since June 30, 2025, state law limits these cities to confirming that the owner lives on the lot when the ADU application is filed (and to regulating short-term rentals). Aurora’s code still lists this requirement — confirm with the planning department how it is applied today.Aurora Unified Development Ordinance §146-3.3.6.G.1.lthe ordinance text"l. The property owner shall occupy either the primary dwelling unit or accessory dwelling." |
| Short-term rental | Yes, only when the owner lives in the main home; Aurora's 180-day-per-year short-term-rental cap still appliesverified September 2026Aurora Unified Development Ordinance §146-3.3.6.G.1.nthe ordinance textUDO 146-3.3.6.G.1.n: "Accessory dwelling units may be used as short-term rentals by a property owner who is living in the primary structure on the property." City Code Sec. 26-219(d): "It shall be unlawful to operate a short-term rental of an entire dwelling for longer than 180 days in any 365-day period. (1) Subsection (c) of this section shall not apply to accessory dwelling units when the property owner lives in the primary structure on the property." |
| Extra parking | 1 additional off-street space, accessed from the alleyverified September 2026Aurora Unified Development Ordinance §146-3.3.6.G.1.kthe ordinance text"k. One additional off-street parking space, accessed from the alley serving the lot, is required." |
| Setbacks | Same as other accessory structures: 5 ft from side lot lines; 3 ft from an alley or 5 ft from a non-alley rear line (a garage-top ADU may match the existing garage's setback)verified September 2026Aurora Unified Development Ordinance §146-3.3.6.G.1.othe ordinance text"o. Each detached accessory dwelling unit shall comply with all setbacks applicable to other accessory structures, except that the required setback for an accessory dwelling unit located on top of an existing garage shall be no less than the setback of the existing garage." | Cross-referenced generic standard: "e. Be set back from each side property line a minimum of five feet; f. Be set back from each rear property line a minimum of: i. Three feet from each alley; ii. Five feet from each rear property line;" |
Source: Aurora Unified Development Ordinance, §146-3.3.6.G · ordinance text retrieved 2026-09-09, re-verified September 2026 · open “the ordinance text” under any figure to read the exact sentence it comes from.
Aurora caps an ADU at 650 sq ft. Owner occupancy: Yes — the owner must live in either the main home or the ADU. Note: Aurora is an HB24-1152 subject jurisdiction. Since June 30, 2025, state law limits these cities to confirming that the owner lives on the lot when the ADU application is filed (and to regulating short-term rentals). Aurora’s code still lists this requirement — confirm with the planning department how it is applied today.
Short-term rental is conditional: Yes, only when the owner lives in the main home; Aurora's 180-day-per-year short-term-rental cap still applies. Parking: 1 additional off-street space, accessed from the alley.
What an ADU adds to the tax bill in Aurora, and the federal benchmark for what it rents for.
Levies: Arapahoe County Assessor, "2025 Taxing District Levy Percentage" report (Tax Year 2025), TAG 0002 — cross-checked against the Arapahoe County "2026 Certification of Levies and Revenues" — example: Arapahoe County TAG 0002; levies differ between tax areas inside Aurora; check your parcel with the county assessor. Rates: Colorado DOLA, TY2026 — the 10% reduction on the first $700,000 of value applies to the local-government portion, once per property. Rents: HUD Fair Market Rents, huduser.gov.
Two ways to build the same unit in Aurora. Both figures are all-in — design, permits, foundation, utility connections and installation.
Published Front Range ranges for a comparable one-off build, 2025–26
≈ $2,100–$2,600 / month fully financed
In Aurora, the 490 fits under the 650 sq ft cap, but Aurora's code also lists lot-size, alley, parking and owner-occupancy conditions, so confirm eligibility with Aurora Planning
≈ $2,800–$3,500 / month fully financed
In Aurora, the 735 is over Aurora's 650 sq ft cap, so it does not fit the code as written
Olerra ranges: published all-in project pricing, September 2026 — site preparation, foundation, utility connections and permitting included.
Permit, utility and tax charges for an ADU depend on your parcel, so we name the agency and link its official schedule rather than guess a number. Olerra’s all-in price already includes them; the calculator below itemizes any amount that has been confirmed.
| Building permit & plan review | Aurora Building Division (Development Services)The fee for a factory-built ADU is not confirmed yet; this agency sets it for your parcel.building permit fee schedule (Fee Schedule 3, 2026) |
| Water & sewer connection | Aurora Water — serves most of townTap and connection charges for an ADU are not confirmed yet; they differ if the ADU shares the main home’s service.tap / connection fees |
| Construction use tax | Aurora taxes building materialsWhether it applies to a factory-built ADU, and its rate and taxable basis, are not confirmed yet.use tax information |
Official sources checked October 25, 2026. Water, sewer and tap charges also depend on whether the ADU shares the main home’s service — the provider confirms which applies.
Free and specific to you. Want to go further?
Yes. The Aurora Unified Development Ordinance permits accessory dwelling units (§146-3.3.6.G), subject to the size, height, setback and use rules quoted above from the ordinance text. Aurora is also an HB24-1152 subject jurisdiction, so since June 30, 2025 state law requires it to allow an ADU wherever it allows a single-family home, with administrative approval; the local standards above still apply. Aurora Planning told us in October 2026 that it applies UDO §146-3.3.6.G to new ADUs: a 650 sq ft maximum, Conditional Use approval for every ADU, and ADUs only in the zone districts that permit them. That differs from the administrative approval state law calls for. The state requirement still applies, and how the two fit together is unresolved, so confirm the current approval process for your parcel with Aurora Planning. Zoning district, lot size and setbacks still decide what fits on a specific lot — the free property check confirms yours.
Yes. An ADU is a new dwelling unit, so Aurora requires a building permit (plus any zoning or site-plan review the code calls for) before construction starts. Building permits for Aurora addresses are handled by Aurora Building Division (Development Services); water and sewer service come from Aurora Water (the local fees table above links their official schedules). Olerra's all-in price includes permitting, and factory-built units are inspected to the same building code as a site-built home.
Per the Aurora Unified Development Ordinance: 650 sq ft. The Olerra Flex Flat 490 fits under the 650 sq ft cap, but Aurora's code also lists lot-size, alley, parking and owner-occupancy conditions, so confirm eligibility with Aurora Planning; the 735 is over Aurora's 650 sq ft cap, so it does not fit the code as written. The free property check confirms what fits on your lot.
It depends: Yes, only when the owner lives in the main home; Aurora's 180-day-per-year short-term-rental cap still applies.
Per the ordinance: Yes — the owner must live in either the main home or the ADU.
A one-off site build with a general contractor typically runs about $500,000–$650,000 for a ~490 sq ft unit. Olerra's factory-built Flex Flats run $300,000–$365,000 (490) and $420,000–$465,000 (735) all-in — site preparation, foundation, utility connections and permitting included.
Roughly $686 per year for every $100,000 of value the ADU adds (for a home already worth $700,000 or more; a little less below that, because 10% of the first $700,000 of value is exempt from the local portion), in the example tax area shown above: Colorado's TY2026 school (7.05%) and local-government (6.80%) assessment rates on the latest certified (TY2025) levy, a mixed-year estimate. Levies differ between tax areas, so check your parcel with the county assessor.
Same method, each city’s own ordinance. The Colorado hub lists every city, and the statewide ADU calculator covers any Colorado address.
Guides and real Colorado numbers from our team — a fresh pick every couple of weeks, or search for exactly what you need.
How to hire an ADU contractor in Colorado, the questions to ask, the red flags to avoid, how licensing works here, and modular versus site-built compared.
Latest articles
Planning departments and journalists are welcome to reference this data.
Olerra ADU Cost Calculator — Aurora, CO. Rules last verified September 9, 2026 against the codified ordinance; tax example: tax year 2025 levy, collected 2026 (Arapahoe County TAG 0002); page released October 29, 2026. https://www.olerra.com/adu-calculator/aurora/ <a href="https://www.olerra.com/adu-calculator/aurora/">Aurora ADU rules & costs</a> Page released October 29, 2026 · rules last verified September 9, 2026 · the oldest dated figure on the page is from September 9, 2026.
Planning estimates, not quotes or legal advice. Rules, fees, levies and rents change — confirm with the city and your lender before committing. Rules data: codified ordinance as of September 9, 2026, re-verified September 2026. Olerra pricing: published all-in project ranges, September 2026. Corrections: sales@olerra.com.
Built for your location and what you want to do.
We'll be in touch before then — a confirmation is on its way to your email.
Thanks — we’ll reply to your email, usually the same day.
Our team is already on it — here’s what happens next.
