Accessory Dwelling Unit (ADU) Regulations in Lone Tree

Max Size-

• Internal & Attached- 50% of primary residence 
• Detached- 40% of primary residence

Max Height- Can not be higher than the primary residence or 25' (whichever is less)

To qualify for an ADU in Lone Tree, your property must meet the following conditions:

• Only one ADU is permitted per lot.
• The ADU must be secondary to a single-family home.
• ADUs are not allowed on properties with duplexes, townhomes, condos, or multifamily units.
• Mobile homes, RVs, and temporary structures cannot be used as ADUs.
• In some cases, homeowners must obtain special approval before building an ADU.

Lone Tree has specific size limitations and design standards for ADUs to ensure they fit within neighborhoods:

• Maximum ADU Size:
  
  • Interior ADUs cannot exceed 50% of the total floor area of the primary home.
  • Detached ADUs cannot exceed 800 sq/ft, unless the zoning district allows a larger size.
• Architectural Compatibility: ADUs must match the design, materials, and character of the primary home.
• Foundation Requirements: ADUs must be permanently affixed to an engineered foundation.
• Setbacks & Placement: ADUs must comply with zoning setback requirements for the lot.

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• HB 24-1152 requires cities to allow ADUs without designated parking, except in these cases:
  ✔ If no parking is currently required for the primary home, parking cannot be required for the ADU.
  ✔ If the lot does not have an existing parking space for the primary home, no additional parking is required.
• Entrances must be positioned to maintain privacy—new ADU entrances visible from the street must be limited.
• Driveways must meet Lone Tree’s building and zoning standards.

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• ADUs must share water and sewer connections with the primary home; separate taps are not permitted.
• All utility bills will be charged to the primary residence’s account holder.
• If an ADU requires a larger water tap size, the homeowner must pay the incremental System Development Fees.

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• HB 24-1152 prohibits cities from requiring owner occupancy meaning ADUs can be rented out separately from the primary home.
• ADUs cannot be sold separately from the main home—they must remain part of the same lot.
• Short-term rentals (STRs) are still prohibited, except in Planned Unit Developments (PUDs) where STRs were previously allowed.

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Under HB 24-1152, all ADU approvals must be handled administratively—meaning there are:
✔ No public hearings
✔ No subjective design reviews
✔ No neighborhood approval required

Homeowners must obtain a building permit before constructing an ADU. The permit process includes:

1. Zoning Verification – Confirm that the property meets ADU requirements.
2. Design Review – Ensure that the ADU complies with size, design, and setback regulations.
3. Building Permit Application – Submit architectural plans, site plans, and supporting documents.
4. Plan Review & Approvals – The city will review the plans to confirm compliance with zoning and building codes.
5. Construction & Inspections – Once approved, construction must follow local regulations and pass final inspections.

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Building an ADU in Lone Tree requires careful planning, compliance with zoning laws, and expert execution that’s where Kindred Tiny Homes comes in.

• We handle everything from design and permitting to construction and final approvals.
• We navigate Lone Tree’s ADU requirements seamlessly, ensuring your project is fully compliant and stress-free.
• We create high-quality, beautifully designed ADUs that enhance property value and maximize functionality.

If you’re considering building an ADU in Lone Tree, contact us today for a free consultation, we’ll walk you through your options and help bring your vision to life!

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