Published, dated market reference. Your assessment numbers above are yours to change.
| Build type | $ / sqft | Typical | Source · as of |
|---|
| Size | All-in range | Note |
|---|
| Item | Share | $ range |
|---|
Net operating income = gross rent × (1 −
vacancy) − gross rent × operating-cost %.
Breakeven (years) = simple undiscounted payback: accumulate
NOI (rent compounding at the growth rate) until it repays total
project cost. Cap 40 years.
Loan payment = standard amortization P·r ⁄ (1
− (1+r)⁻ⁿ); a HELOC is interest-only during
its 10-yr draw, then amortizes.
Property tax = added market value × blended 6.7%
assessment rate × mill levy ÷ 1000 (accurate within ~1%
for these cities).
Wealth = value created day one (added market value −
project cost) + appreciation on that added value + loan principal
paid + cumulative cash flow, over your hold.
No. Colorado assessors add only what the ADU contributes to your property's market value — in strong markets like Boulder often more than the build cost† — on top of your existing valuation. The new value first appears the January after the ADU is finished, and you start paying on it the following year.
Not exactly. HUD's FY2026 Fair Market Rents are 40th-percentile recent-mover rents used for voucher programs — a solid, conservative baseline. A brand-new, well-finished ADU often rents above FMR. We default to a conservative baseline — HUD FMR in most areas, new-unit comps in Boulder — and let you edit the rent to your local numbers.
The 2024 state ADU law requires many Front Range municipalities to allow at least one ADU on single-family lots and limits the most restrictive local barriers, like blanket owner-occupancy mandates. Cities still set their own size caps, fees and design rules — which is why Boulder, Denver and Fort Collins look so different in this tool.
Boulder requires fire sprinklers on detached ADUs, which adds roughly $3–10K to construction, and its plant-investment fees are among the highest in the metro. The upside: sharing your main house's existing water and sewer service can cut about $12,700 off those fees — toggle it in section 1.
If your lot is served by city utilities, ADU fees run around $14K. But if you're in a special district like Fort Collins–Loveland Water District (FCLWD), a new water tap was $55,685 on the January 2026 schedule and can top $113K on large lots. Confirm your water district before you budget anything.
No. This is a pre-tax planning estimate to help you think through the decision. It is not a quote, an appraisal, or financial advice, and Olerra is not a lender or financial advisor. Confirm fees, rates and tax treatment with your city, lender and a tax professional before committing.
In production this opens Olerra's scheduling flow — an Olerra advisor walks your property, confirms fees with your city and water district, and quotes a fixed price on a 490 or 735. For this prototype it's a stub; no data is sent.
