ADU Regulations in Pennsylvania (PA)
Pennsylvania is rated Moderate for ADU construction with an ADU-friendliness score of 30/100 (Restrictive). Pennsylvania does not have a statewide ADU law — regulations are set entirely by local jurisdictions. Owner must reside on the property. Additional parking may be required. Pennsylvania has no statewide ADU law. Philadelphia and Pittsburgh have local ADU provisions. Pennsylvania's Municipalities Planning Code gives local governments broad zoning authority. ADU policies vary widely across the state's municipalities and townships.
Full ADU Regulations Summary for Pennsylvania
| ADUs Allowed | Yes |
| Statewide ADU Law | No |
| Maximum ADU Size | Set locally |
| Owner Occupancy Required | Yes |
| Parking Required | Yes |
| Minimum Setback | Set locally |
| Permitting Timeline | Varies by jurisdiction |
| Impact Fees | Varies by jurisdiction |
| Long-Term Rental Allowed | Yes |
| Short-Term Rental (Airbnb) Allowed | Yes |
| Ease of Building | Moderate |
ADU Regulations by City in Pennsylvania
ADU rules can vary by city even within the same state. Without a statewide ADU law, Pennsylvania cities set their own rules, and policies can differ significantly. Below are ADU details for 3 cities in Pennsylvania.
Philadelphia
ADUs allowed in most residential zones. Philadelphia permits attached ADUs (in-law suites) and some detached ADUs. Permit required.
Pittsburgh
ADUs permitted in certain residential zones. Pittsburgh updated zoning in 2023 to expand ADU options.
State College
ADUs allowed in some zones. State College Borough has ADU provisions for student and workforce housing.
How Pennsylvania Compares to Other States
Below is a comparison of Pennsylvania with five states that have similar ADU-friendliness scores. This comparison helps illustrate where Pennsylvania stands nationally.
| State | Score | Statewide Law | Parking Req? | Owner Occ? | Ease |
|---|---|---|---|---|---|
| Pennsylvania (PA) | 30 | No | Yes | Yes | Moderate |
| Alabama (AL) | 30 | No | Yes | Yes | Difficult |
| Arkansas (AR) | 30 | No | Yes | Yes | Difficult |
| Delaware (DE) | 30 | No | Yes | Yes | Moderate |
| Georgia (GA) | 30 | No | Yes | Yes | Moderate |
| Idaho (ID) | 30 | No | Yes | Yes | Moderate |
Frequently Asked Questions About ADUs in Pennsylvania
Can I build an ADU in Pennsylvania?
Yes, ADUs are allowed in Pennsylvania. However, Pennsylvania does not have a statewide ADU law, so the specific rules depend on your city or county's zoning code. Some cities are more permissive than others. The ease of building is rated "Moderate" with a friendliness score of 30/100.
Do I need to live on the property to have an ADU in Pennsylvania?
Yes, Pennsylvania generally requires owner occupancy — the property owner must live either in the main house or the ADU. This means you cannot rent out both units simultaneously. Note: individual cities may have their own owner-occupancy rules, so check your local zoning.
How big can an ADU be in Pennsylvania?
Pennsylvania does not set a statewide maximum ADU size — this is determined by your local jurisdiction. Common local limits range from 600 to 1,200 square feet. Check your city's zoning code for the specific maximum.
Do I need extra parking for an ADU in Pennsylvania?
Pennsylvania may require additional off-street parking for ADUs. The specific number of spaces depends on your local jurisdiction. This can be a significant barrier if your lot has limited space for parking.
Can I rent out my ADU in Pennsylvania?
Yes, long-term rentals of ADUs are allowed in Pennsylvania. Short-term rentals (like Airbnb) are also generally permitted, though your city may have separate short-term rental regulations.
How long does it take to get an ADU permit in Pennsylvania?
The permitting timeline in Pennsylvania is: Varies by jurisdiction. Without a statewide mandate, permitting timelines depend entirely on your local jurisdiction's review process. Actual timelines can be affected by plan review backlogs, inspection scheduling, and the complexity of your project. Pre-approved ADU plans, where available, can significantly speed up the process.
Check ADU Rules for Your City
Use our ADU regulations lookup tool to find the specific rules for your city in Pennsylvania, or browse all 50 states to compare ADU regulations across the country. Remember that local rules may be more specific than state-level regulations.