ADUs in University City: What Zoning Allows

Thinking about adding a small apartment for family or extra income in University City? Philadelphia does allow accessory dwelling units in certain situations, but the rules are specific and narrow. If you own a rowhouse, you may face limits, while historic or twin homes often have more options. This guide walks you through what zoning permits, how the historic exception works, and the steps to get an ADU approved in University City. Let’s dive in.

Quick snapshot: what Philadelphia allows

• ADUs are permitted only on lots with a single-family use in a detached or semi-detached building, in the areas listed in the Code. Historic buildings can qualify even if attached. See the Accessory Dwelling Unit standards in §14-604(11) of Philadelphia’s Zoning Code for details.
• Either the main home or the ADU must be owner-occupied, and you must record an owner-occupancy deed restriction before final occupancy. Removal later requires Zoning Board approval. Review the deed restriction requirement in the Code.
• You can build one ADU per lot. The maximum size is 800 square feet, except that historic properties may have different limits.
• ADUs are not allowed in RSA-5 and CMX-1 districts unless the property qualifies under the historic exception. See the supplemental use regulations for district exclusions.

References: Philadelphia Zoning Code §14-604(11), Supplemental use regulations, and City Council Bill No. 190612 establishing these standards.

How the rules fit University City

University City includes a mix of rowhouses, twin homes, larger detached houses, multifamily buildings, and major institutions. Many blocks are also within local or national historic districts. That mix matters because the Code mainly allows ADUs on single-family detached or semi-detached lots, and it gives a special path for historic properties. Learn more about the neighborhood’s building context in the University City overview.

Historic exception could unlock options

If your home is designated historic or contributes to a local historic district, the Code allows ADUs even in attached buildings that would otherwise be ineligible. Historic properties may also have different size or placement flexibility. If you think your property might be historic, contact the Philadelphia Historical Commission to confirm status and any required reviews.

Detached backyard cottages

You can place an ADU in a detached accessory building only if that structure already existed as of January 1, 2020. In University City, many lots do not have qualifying garages or carriage houses, which makes brand-new backyard cottages hard to permit by right.

District exclusions to watch

If your property is in RSA-5 or CMX-1, ADUs are generally not allowed unless the property is historic. Many University City rowhouse blocks fall in RSA-type districts, which is why ADU uptake here has been limited.

Eligibility checklist

• Confirm zoning. Use the City’s Atlas tool to look up your parcel’s zoning district and overlays. Start with the City’s guide to find location and zoning information.
• Confirm building type and use. Is it a single-family detached or semi-detached home? If attached, check if it is historic.
• Check historic status. Ask the Historical Commission if your property is designated or contributing to a district.
• If planning a detached ADU, verify the detached structure existed before January 1, 2020.
• Plan for owner occupancy. Be ready to record the required deed restriction.

Permits and steps

1. Research your lot. Use Atlas to confirm zoning, then review §14-604(11) for ADU standards.
2. Pre-application consultation. Contact the Department of Planning & Development for zoning questions and L&I for permit scope using the City’s information portal.
3. Prepare plans. Your design must meet building, electrical, plumbing, mechanical, and fire codes.
4. Apply for zoning and building permits. L&I reviews plans and issues permits.
5. Record the deed restriction. Before final occupancy, record the owner-occupancy deed restriction and affidavit with the Department of Records.
6. Final inspections and Certificate of Occupancy. L&I closes permits when the work passes inspection.

Key design standards to plan for

• One unit per lot and a maximum ADU size of 800 square feet, unless historic.
• Entrances: only one street-facing entrance is allowed on the front facade unless a second entrance already existed.
• The ADU can be within the principal home or in a detached accessory building that existed before January 1, 2020.
• Owner-occupancy is required and must be recorded as a deed restriction.

See Philadelphia Zoning Code §14-604(11) for the full standards.

Real scenarios in University City

• Detached or twin home: If your single-family detached or semi-detached home is in an eligible district, you may be able to convert a basement or attic into an ADU, or use a pre-2020 garage. You still must meet the 800 square foot limit and record the deed restriction.
• Typical rowhouse: Many rowhouses sit in RSA districts where ADUs are not allowed unless the property is historic. Without historic status, you would likely need a variance from the Zoning Board, which is not guaranteed.
• New backyard cottage: The Code limits detached ADUs to accessory buildings that existed before 2020. Owners often pivot to an interior conversion if no qualifying structure exists.
• Historic property: Historic designation can open the door for an ADU in attached buildings and may allow different size or placement standards. Expect Historic Commission review as part of the process.

Who to contact and key resources

• Zoning standards for ADUs: Philadelphia Zoning Code §14-604(11)
• District exclusions (RSA-5, CMX-1): Supplemental use regulations
• Property research and zoning lookups: City’s guide to find location and zoning information
• Legislative history: City Council Bill No. 190612
• Historic status and review: Philadelphia Historical Commission

Ready to explore your options?

If you are weighing an ADU as part of a buy, sell, or hold strategy in University City, let’s talk through eligibility, timeline, and value impact together. Reach out to Tom Englett for a clear, concierge plan tailored to your property.

FAQs

Are ADUs allowed in University City rowhouses?

• Most attached rowhouses are not eligible unless the property is designated historic, because the Code focuses ADUs on single-family detached or semi-detached lots and excludes RSA-5 districts.

What is the maximum ADU size in Philadelphia?

• The general cap is 800 square feet per lot, with potential differences for historic properties under the Code.

Do I have to live on the property if I add an ADU?

• Yes, either the main home or the ADU must be owner-occupied, and you must record a deed restriction that cannot be removed without Zoning Board approval.

Can I build a new backyard cottage in University City?

• A detached ADU is only allowed in an accessory building that existed before January 1, 2020, so brand-new backyard cottages are typically not permitted by right.

Where can I check my property’s zoning and historic status?

• Start with the City’s guide to find zoning information and contact the Historical Commission to confirm historic designation or district contributions.