ADU (Accessory Dwelling Unit) Permit in Philadelphia (2026)

Can I build an ADU (accessory dwelling unit) in my Philadelphia rowhouse rear yard?

Yes. Philadelphia allows accessory residential units (ARUs) in RSA and RSD zones subject to Title 14 standards. For a typical rowhouse (RSA-5 zone), you can build a detached accessory structure in the rear yard up to 800 sqft and 24 ft height, with a 12 ft rear setback maintained. Your rear yard must be deep enough to accommodate the structure and setback. L&I zoning and building permits required. No parking requirement for ADUs.

What is the eCLIPSE permit system and how do I use it?

eCLIPSE is Philadelphia L&I's online permit and licensing portal (eclipse.phila.gov). You can apply for zoning permits, building permits, trade permits, and licenses online. The system tracks application status, allows document uploads, and schedules inspections. For residential projects, you typically need a zoning permit first (verifying compliance with Title 14), then a building permit (verifying construction code compliance). Philadelphia L&I Customer Service Center at 1401 JFK Blvd assists with complex applications.

Do I need Historical Commission approval to renovate my Philadelphia rowhouse?

It depends on your property's designation status. If your property is a designated Philadelphia landmark or is a contributing structure in a historic district (approximately 15,000 properties citywide), all exterior changes require a Certificate of Appropriateness (CoA) from the Philadelphia Historical Commission before L&I issues a permit. Interior changes do not typically require PHC approval. Check your property at Atlas (atlas.phila.gov) to see if it has a historical designation. In historic neighborhoods like Old City, Society Hill, and Germantown, many properties require PHC review.

How does Philadelphia's stormwater fee affect my property?

Philadelphia Water Department charges a Stormwater Management Service Charge (SMSC) based on the total impervious surface area of your property (roof area + driveways + paved areas). The fee is billed monthly with your water bill. When you add impervious surface (additions, new driveways, patios), PWD may recalculate your fee. Green stormwater infrastructure (rain garden, permeable paving, green roof) can qualify for a Stormwater Management Credit Program (SMCP) reducing your charge. Philadelphia's green stormwater program is nationally recognized.

Are Airbnb and short-term rentals allowed in Philadelphia?

Yes, with a Limited Lodging Operator License ($200/year). You must be a primary resident of the property (owner or renter). Hosted rentals (you're present) are allowed without a nightly cap. Unhosted rentals (you're away) are capped at 90 nights/year and require an additional Visitor Accommodation designation. Maximum 3 guest rooms per unit. Philadelphia Hotel Tax (8.5%) applies. License number must be displayed on your listing. Airbnb and VRBO collect and remit the tax.

What makes Philadelphia rowhouses unique for zoning purposes?

Philadelphia rowhouses are built wall-to-wall with shared party walls — zero side setbacks in RSA-5 zone (the most common residential zone). This means additions and alterations must be evaluated for party wall impacts. Rear yards (typically 10-20 ft deep) are the primary space for ADUs and accessory structures. Flat roofs are standard, making rooftop deck additions and solar installation common but requiring permits. Historic district designations affect a large proportion of rowhouse neighborhoods. L&I's Rowhouse Exemption provisions address common modifications unique to this building type.