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Westminster spans Jefferson and Adams counties with neighborhoods ranging from established ranch homes to newer subdivisions. Here’s what ADU rules look like in Westminster today.
| ADUs Allowed? | ✅ Yes — under HB 24-1152 compliance |
| Maximum Size | 1,000 sq ft or 50% of primary home area |
| ADU Types Permitted | Detached, attached, basement, garage conversion |
| Owner-Occupancy Required? | Not required under HB 24-1152 |
| Parking Requirement | 1 space per ADU |
| HOA Override? | HOAs cannot prohibit ADUs per HB 24-1152 in covered zones |
| Short-Term Rental (STR)? | Westminster STR rules apply; verify with city |
| Permit Path | Administrative approval for compliant ADUs |
| Estimated Permit Timeline | 8–14 weeks typical |
| Official Source | City of Westminster Planning & Development |
⟳ Last reviewed: October 2026. ADU rules change. Always verify current code with Westminster before starting a project. View official source →
Westminster straddles Adams and Jefferson counties, which creates some variability in utility providers and permit workflows depending on your specific address. The city has very little ADU information published online for homeowners, which means most residents are navigating this without clear guidance — a significant opportunity for homeowners who want to move quickly. Westminster has a mix of 1970s–1990s ranch homes with large lots that can accommodate detached ADUs.
Not sure if your lot qualifies? The ADU quiz takes 3 minutes and gives you a personalized eligibility summary based on your property type, location, and goals. Take the free ADU quiz →
| Detached Backyard Cottage | $195,000–$360,000 |
| Garage Conversion | $50,000–$130,000 |
| Basement ADU Conversion | $38,000–$105,000 |
| Permit Fees (estimate) | $3,000–$9,000 |
| Utility Tap Fees (detached) | $5,000–$15,000 (Westminster Water or various Adams/Jefferson County districts) |
| Estimated Monthly Rent | $1,600–$2,500/month |
| Estimated Break-Even | 7–11 years for detached; 3–5 years for conversion |
Local note: Westminster’s lower land costs compared to closer-in suburbs can make ADU ROI stronger. Confirm your utility district before budgeting — the city’s county split affects provider fees.
Cost ranges reflect 2026 Denver metro construction pricing. Individual project costs depend on site conditions, finishes, utility distances, and contractor selection. Get multiple bids before committing to a budget.
Official Sources
Rules and fees change. Always verify current requirements directly with your local jurisdiction and utility provider before starting a project.
Answer 7 questions to see your estimated cost range, likely ADU type, and local eligibility — free, no sign-up required.