Permit Required? Required
Typical Fee Range $1,500–$5,000 Governed by local zoning; building permits range from $500–$2,000 plus trade permits.
Fee Method Valuation-based
Apply Online Apply at Philadelphia Department of Licenses and Inspections →

What's Required in Philadelphia

  • Permit required for all Accessory Dwelling Units (ADUs), detached or attached
  • Property must be owner-occupied (either the main house or the ADU)
  • Separate zoning approval is typically required as a prerequisite
  • Must meet PA energy efficiency requirements and IRC ceiling heights (min 7 ft)
  • Smoke and CO detectors mandatory in every sleeping room and hallway
  • At least one egress window per bedroom is required

How Much Does an ADU Permit Cost in Philadelphia?

Budget $1,500–$5,000 for the Philadelphia permit itself (valuation-based), issued by the Philadelphia Department of Licenses and Inspections — but treat that as the entry fee, not the total. ADUs are full dwelling units, so the permit stack usually includes building, electrical, plumbing, and mechanical trade permits, plus plan review. One local note: governed by local zoning; building permits range from $500–$2,000 plus trade permits. Get an itemized fee estimate from the department before finalizing your budget; the spread between a simple conversion and a new detached build is wide.

ADU Size Limits and Zoning Rules in Philadelphia

Before drawing plans, check the two gates that sink most ADU projects: size and zoning. Size ceilings vary by lot and ADU type (attached, detached, or conversion), so confirm your specific configuration. Other recorded conditions: property must be owner-occupied (either the main house or the ADU). Setbacks, height limits, and utility connections layer on top of those rules. The Philadelphia Department of Licenses and Inspections can confirm what your specific lot allows — worth doing before you pay for architectural drawings rather than after.

How to Get a ADU Permit in Philadelphia

1

Step 1: Zoning Variance/Approval

Check Philadelphia zoning for ADU eligibility; historic properties have specific bonus paths.

2

Step 2: Full IRC Plans

Prepare detailed architectural, structural, and energy (Title 24) plans.

3

Step 3: eCLIPSE Submission

Apply for the 'New Construction' or 'Major Alteration' permit via eCLIPSE.

4

Step 4: Fee Payment

Pay building fees ($500+) plus trade permit fees for electrical and plumbing.

5

Step 5: Inspection Sequence

Schedule Slab, Framing, MEP Rough-in, and Final Inspections.

Frequently Asked Questions

Yes, but it depends on your specific zoning district and lot size; historic properties have more flexibility.
Total permit costs (building + trades) typically range from $1,500 to $5,000.
Zoning rules vary, but many ADUs are limited by lot coverage and height rather than a specific square footage.