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: rents floored at $1,754/mo. 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, Colorado law guarantees one ADU by right on any lot with a single-family home here.
| 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. |
| Owner occupancy | Yesverified September 2026Note: Golden is an HB24-1152 subject jurisdiction. Since June 30, 2025, state law limits such cities to confirming the owner lives on the lot when the ADU application is filed (and to regulating short-term rentals); a standing owner-occupancy rule on a long-term-rental ADU is no longer enforceable. The ordinance text may predate that change — confirm current practice with the planning department.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 September 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.
The owner must live on the property (main house or ADU) — common across Colorado (11 of the 14 codes we’ve read require it), and the rule that most often shapes rental plans. Note: Golden is an HB24-1152 subject jurisdiction. Since June 30, 2025, state law limits such cities to confirming the owner lives on the lot when the ADU application is filed (and to regulating short-term rentals); a standing owner-occupancy rule on a long-term-rental ADU is no longer enforceable. The ordinance text may predate that change — confirm current practice with the planning department.
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 conservative floor on 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). 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
≈ $2,800–$3,500 / month fully financed
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 one ADU to be allowed on any lot with a single-family home. 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. Both Olerra Flex Flats — the 490 and the 735 — are designed to fit typical Colorado caps; check the rules table above for the exact ordinance text.
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 such cities to confirming the owner lives on the lot when the ADU application is filed (and to regulating short-term rentals); a standing owner-occupancy rule on a long-term-rental ADU is no longer enforceable. The ordinance text may predate that change, so confirm current practice with the planning department.
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, using the local mill levy split across Colorado's TY2026 school (7.05%) and local-government (6.80%) assessment rates.
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.
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Planning departments and journalists are welcome to reference this data.
Olerra ADU Cost Calculator — Golden, CO. Data updated August 25, 2026. https://www.olerra.com/adu-calculator/golden/ <a href="https://www.olerra.com/adu-calculator/golden/">Golden ADU rules & costs</a> Data as of August 25, 2026, the oldest figure on the page.
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 September 2026. Olerra pricing: published all-in project ranges, September 2026. Corrections: sales@olerra.com.
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