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.
Lyons’s real rules, taxes and rents — read from the codified ordinance, every figure sourced and dated. Here: a HUD benchmark rent of $1,795/mo for a 1-bed. Run your own numbers below, free.
Read from the Lyons Municipal Code itself — the operative legal text, not a website summary. Lyons 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.
| Size relative to the main house | 100% of principal dwelling size (or up to 800 sq ft if the principal dwelling is 800 sq ft or less); no size limit applies to ADUs located in a basementverified September 2026Lyons Municipal Code §16-10-70the ordinance textADUs shall not be larger than the principal dwelling unit unless the principal dwelling unit is eight hundred (800) square feet or less in which case the ADU may be a maximum of eight hundred (800) square feet. These size limitations shall not apply to ADUs located in a basement, for which there is no size limit. |
| Owner occupancy | No — no owner-occupancy requirement (the ADU and the main house must stay under one title)verified October 2026Lyons Municipal Code §16-10-70the ordinance textSec. 16-10-70(e): "The fee ownership of the principal dwelling and accessory dwelling unit shall not be separated." No part of the ADU section requires the owner to live on the property. |
| Short-term rental | Noverified September 2026Lyons Municipal Code §16-10-70the ordinance textThere shall be no short-term lodgers within an ADU. Owners shall not lease or rent Accessory Dwelling Units for a period of time or term of occupancy of less than thirty (30) days. |
| Extra parking | None beyond the main houseverified September 2026Lyons Municipal Code §16-10-70the ordinance textParking requirements. Off-street parking is not required. |
| Fire sprinklers | No (stated only for ADUs of 800 sq ft or less)verified September 2026Lyons Municipal Code §16-10-70the ordinance textno sprinkler system shall be required for any ADU of eight hundred (800) square feet or less |
Source: Lyons Municipal Code, §16-10-70 · ordinance text retrieved 2026-10-22, re-verified October 2026 · open “the ordinance text” under any figure to read the exact sentence it comes from.
Short-term rental of the ADU is not permitted, so the model here is long-term tenancy or family use. No extra parking is required for the ADU.
Property tax runs heavier than most of the state here: 128.681 mills total in the example tax area (Boulder County tax area 0700), about 43% above the median of the Colorado tax areas we track (levies vary by parcel).
And Lyons is one of only 30 Colorado jurisdictions certified ADU Supportive, which makes residents eligible for CHFA’s state-backed ADU financing — an interest-rate buydown and credit enhancement offered through participating lenders. Most of the Front Range doesn’t have this lever.
What an ADU adds to the tax bill in Lyons, and the federal benchmark for what it rents for.
Levies: Boulder County Assessor - Mill Levy Changes 2024 to 2025 (xlsx), sheets 'Changes_by_Tax_Area' and 'Changes_by_Authority' — example: Boulder County tax area 0700; levies differ between tax areas inside Lyons; 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 Lyons. 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 Lyons’s size rule
≈ $2,800–$3,500 / month fully financed
Fits Lyons’s size 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 Lyons Municipal Code permits accessory dwelling units (§16-10-70), subject to the size, height, setback and use rules quoted above from the ordinance text. Lyons 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 Lyons 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.
No — the ordinance does not permit short-term rental of an ADU here, so plan on long-term tenancy or family use.
Per the ordinance: No — no owner-occupancy requirement (the ADU and the main house must stay under one title).
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 $889 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.
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Planning departments and journalists are welcome to reference this data.
Olerra ADU Cost Calculator — Lyons, CO. Rules last verified October 22, 2026 against the codified ordinance; tax example: tax year 2025 levy, collected 2026 (Boulder County tax area 0700); page released October 22, 2026. https://www.olerra.com/adu-calculator/lyons/ <a href="https://www.olerra.com/adu-calculator/lyons/">Lyons ADU rules & costs</a> Page released October 22, 2026 · rules last verified October 22, 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.
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