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.
Golden’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 Golden Municipal Code itself — the operative legal text, not a website summary. Golden 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.
| Maximum ADU size | 800 sq ft cap (if principal dwelling is 1,000+ sq ft, or 50% of primary living space if smaller); flat 500 sq ft cap (if principal dwelling is under 1,000 sq ft); 200 sq ft minimum in all casesverified September 2026Golden Municipal Code §18.28.04.05the ordinance textFor a single-household or two-household dwelling unit of 1,000 square feet or more of living space, the accessory dwelling unit shall be no larger than 50 percent of the living space of such principal dwelling unit, or 800 square feet, whichever is smaller. For a principal dwelling unit of less than 1,000 square feet of living space, the accessory dwelling unit shall be no larger than 500 square feet. No accessory dwelling unit shall be less than 200 square feet. |
| Size relative to the main house | 50% of primary living space applies only when the principal dwelling is 1,000+ sq ft (capped at 800 sq ft); no percentage rule applies for principal dwellings under 1,000 sq ft, which instead face a flat 500 sq ft capverified September 2026Golden Municipal Code §18.28.04.05the ordinance textFor a single-household or two-household dwelling unit of 1,000 square feet or more of living space, the accessory dwelling unit shall be no larger than 50 percent of the living space of such principal dwelling unit, or 800 square feet, whichever is smaller. For a principal dwelling unit of less than 1,000 square feet of living space, the accessory dwelling unit shall be no larger than 500 square feet. |
| Minimum ADU size | 200 sq ftverified October 2026Golden Municipal Code §18.28.04.05the ordinance textNo accessory dwelling unit shall be less than 200 square feet. For the purposes of this subsection, floor area calculations shall exclude any garage, porch or similar area. |
| Owner occupancy | Yesverified September 2026Note: Golden 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). Golden’s code still lists this requirement — confirm with the planning department how it is applied today.Golden Municipal Code §18.28.04.05the ordinance textThe property owner, as reflected in title records and evidenced by voter registration, vehicle registration or other similar means, must occupy either the principal dwelling unit or accessory dwelling unit. |
| Extra parking | 1 additional spaceverified September 2026Golden Municipal Code §18.28.04.05the ordinance textOne on-site parking space shall be required for an ADU. Parking for the ADU is in addition to the required parking for the principal dwelling unit. |
Source: Golden Municipal Code, §18.28.04.05 · ordinance text retrieved 2026-08-25, re-verified October 2026 · open “the ordinance text” under any figure to read the exact sentence it comes from.
Golden’s size cap is conditional rather than a single number: 800 sq ft cap (if principal dwelling is 1,000+ sq ft, or 50% of primary living space if smaller); flat 500 sq ft cap (if principal dwelling is under 1,000 sq ft); 200 sq ft minimum in all cases — worth reading closely before sizing a unit.
Owner occupancy: yes. Note: Golden 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). Golden’s code still lists this requirement — confirm with the planning department how it is applied today.
Plan for 1 dedicated off-street space beyond the main house’s parking — on a tight lot, often a bigger siting constraint than the size cap.
What an ADU adds to the tax bill in Golden, and the federal benchmark for what it rents for.
Levies: Jefferson County Assessor, 'Tax Authority Information and Reports' — 2025 Tag with Mill Levy All; 2025 Tax Authorities with Mill Levy All; 2024 Tag with Mill Levy and Authorities All (composition cross-check: summing 2025 per-authority mills for this authority set reproduces the 2025 tag total of 90.6670 exactly) — example: Jefferson County TAG 5002; levies differ between tax areas inside Golden; 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 Golden. 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
Fits Golden’s size rule
≈ $2,800–$3,500 / month fully financed
In Golden, the 735 needs a main home with at least 1,470 sq ft of living space (the 50% rule)
Olerra ranges: published all-in project pricing, September 2026 — site preparation, foundation, utility connections and permitting included.
Free and specific to you. Want to go further?
Yes. The Golden Municipal Code permits accessory dwelling units (§18.28.04.05), subject to the size, height, setback and use rules quoted above from the ordinance text. Golden 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. 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 Golden requires a building permit (plus any zoning or site-plan review the code calls for) before construction starts. 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 Golden Municipal Code: 800 sq ft cap (if principal dwelling is 1,000+ sq ft, or 50% of primary living space if smaller); flat 500 sq ft cap (if principal dwelling is under 1,000 sq ft); 200 sq ft minimum in all cases. The Olerra Flex Flat 490 fits (main homes under 1,000 sq ft are capped at 500 sq ft); the 735 needs a main home with at least 1,470 sq ft of living space (the 50% rule). The free property check confirms what fits on your lot.
Yes — the owner must live in either the main house or the ADU. Note: Golden 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). Golden's code still lists this requirement, so confirm with the planning department how it is applied today.
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 $628 per year for every $100,000 of value the ADU adds, 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 — Golden, CO. Page updated October 9, 2026; rules verified October 2026. https://www.olerra.com/adu-calculator/golden/ <a href="https://www.olerra.com/adu-calculator/golden/">Golden ADU rules & costs</a> Page updated October 9, 2026. The oldest dated figure on the page is from August 25, 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 August 25, 2026, re-verified October 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.
