How Centennial Handles Accessory Structures: A Practical Guide

Centennial maintains 39 local ordinances across all categories, and 4 of those deal specifically with accessory structures. Here is a breakdown of what the city actually requires, what is prohibited, and where Centennial falls on the strict-to-permissive spectrum compared to other cities.

Carport Rules

Centennial regulates detached carports under Land Development Code Section 12-3-603 as accessory structures. Detached carports serving attached single-family or multifamily dwellings must be set back at least 20 feet from a building setback line on adjacent lots of a different dwelling type. General accessory structures have 5-foot rear and interior side setbacks and a 17-foot height cap.

Key details: Side/Rear Setback: 5 feet (general accessory). Height Limit: 17 feet / one story max. Size Cap: ≤25% rear yard or 600 sq ft. Code: LDC §12-3-603.

Carport built without permit: stop-work order and after-the-fact permit fees. Setback or height violation: removal or relocation order. Encroachment into easement: required removal at owner's expense.

ADU Rules

Centennial approved ADU regulations unanimously in 2024. Interior ADUs are limited to 50% of the primary residence. Detached ADUs cannot exceed 800 sq ft. ADUs must match the primary home's design. Under HB 24-1152, owner occupancy cannot be required, and STRs in ADUs are prohibited except in PUDs.

Key details: Interior Max: 50% of primary residence. Detached Max: 800 sq ft. Design: Must match primary home. STR in ADU: Prohibited (except PUDs).

Building without a permit: building code violation. Exceeding size limits: zoning violation. Operating an STR in an ADU outside a PUD: code violation.

Shed Rules

Centennial regulates accessory structures through the Land Development Code. Small sheds typically do not require building permits but must comply with setback requirements. Structures over 50 sq ft in certain districts require screening with a 6-foot fence. HOA approval may also be needed.

Key details: Permit Exempt: Generally under 200 sq ft. Screening: Required for 50+ sq ft structures. Height: Cannot exceed primary dwelling. HOA Rules: Approval may be needed.

Building in setback: zoning violation. Failure to screen: code enforcement action.

The rules around shed rules in Centennial lean permissive, but that does not mean anything goes.

Garage Conversions

Centennial permits garage conversions as a form of ADU under its 2024 ADU ordinance and Colorado HB 24-1152. Conversions require building permits and must meet residential code including 7'6" ceiling height. Under state law, cities should not require replacement parking for garage-to-ADU conversions.

Key details: Permit: Required. Ceiling Height: 7 ft 6 in minimum. Replacement Parking: Not required per state guidance. Entrance: Side or rear preferred.

Conversion without permit: building code violation. Occupying non-code-compliant space: safety violation with potential red-tag.

The Bottom Line

Centennial'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 Centennial is broadly strict or permissive.

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