Pennsylvania ADU Laws

Complete 2026 guide to accessory dwelling unit regulations

○Local Control Only

📋Quick Facts

Owner Occupancy
May be required
Parking
Set locally
Approval Process
Varies locally

⚠️Key Requirements & Restrictions

  • •No statewide ADU law
  • •Rules vary entirely by county and municipality
  • •Bucks County requires foundation (no tiny homes on wheels)
  • •York County prohibits ADUs as permanent residences
  • •Must comply with PA Building Code 2018 (based on IRC)

📖Detailed Analysis

No statewide ADU law - entirely local control. Philadelphia has ADU regulations (attached or in accessory buildings like garages/basements). Pittsburgh had ADU Overlay District pilot in Garfield neighborhood (2018), considering city-wide expansion. Lancaster County is ADU-permissive without strict size mandates. Bucks County requires foundations. York County prohibits permanent ADU residency. Tiny homes on wheels classified as RVs under 2018 Board of Vehicle Act 134. Must navigate municipality-specific zoning - city ordinances can supersede county laws.

🔗Official Resources

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⚠️ Disclaimer

The information provided on this website is for general informational purposes only and does not constitute legal, financial, or professional advice. ADU laws, regulations, and requirements vary by jurisdiction and change frequently. While we strive to keep this information accurate and up-to-date, we make no representations or warranties of any kind about the completeness, accuracy, reliability, or suitability of this information. Always consult with qualified local professionals, including attorneys, architects, and your local planning department, before making any decisions regarding ADU construction or investment. Use of this information is at your own risk.

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Last updated: February 2026