Accessory Structures in Westminster, CO: What Residents Actually Need to Know

If you live in Westminster or are thinking about moving there, accessory structures are one of those things you probably won't think about until they affect you directly. Westminster has 5 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

ADU Rules

Westminster regulates ADUs through local zoning. Colorado HB 24-1152 requires certain municipalities to allow ADUs. Rules vary by city.

Key details: State Law: HB 24-1152 (2024). Local Rules: Vary by city. Permit: Building permit required. HOA: May restrict.

Unpermitted ADU: standard building code enforcement. May require demolition or legalization. Occupying unpermitted dwelling: code violation.

Garage Conversions

Westminster may allow garage conversions with permits. Colorado has no statewide garage conversion mandate. Replacement parking may be required.

Key details: Permit: Building permit required. Parking: Replacement usually required. Insulation: Cold weather standards. HOA: Usually prohibited.

Unpermitted conversion: building code enforcement. Must bring to code or restore. Safety violations: immediate correction.

Carport Rules

Westminster requires permits for carport construction. Setback requirements, height limits, and lot coverage maximums apply.

Key details: Permit: Required. Side Setback: 3 to 5 feet typical. Lot Coverage: Counts toward maximum. HOA: May restrict or prohibit.

Unpermitted carports: stop-work orders, required removal or retroactive permitting with penalty fees. Fines $200 to $1,000.

Tiny Homes

Westminster regulates tiny homes differently based on whether they are on a permanent foundation or on wheels. Zoning and minimum square footage requirements apply.

Key details: Foundation: Treated as dwelling. On Wheels: RV classification typically. Min Size: 400 to 800 sq ft varies. ADU Path: May allow as secondary.

Unpermitted dwellings: removal or retroactive permitting. Zoning violations: fines and required relocation. Occupancy without certificate: prohibited.

Shed Rules

Westminster allows small sheds without permits (typically under 120 to 200 sq ft). Larger structures need building permits. Setback requirements apply.

Key details: No Permit: Under 120 to 200 sq ft. Permit: Over threshold. Setbacks: Per zoning code. Snow Load: Check local requirements.

Unpermitted structure: retroactive permit with penalty. Non-compliant setback: modification or removal.

If you are coming from a city with tighter rules, you will find Westminster gives residents more flexibility on shed rules.

The Bottom Line

Westminster's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Westminster is broadly strict or permissive.

These rules come from Westminster's publicly available municipal code. For complete penalty schedules, exemption details, and answers to common questions, see the individual ordinance pages throughout this guide.