Permit Required? Required
Typical Fee Range $500–$2,000 New ADU state laws effective 2025; local rules must align by Oct 2026.
Fee Method Valuation-based
Apply Online Apply at Department of Permits, Approvals and Inspections →

What's Required in Baltimore

  • Permit required for additions or conversions to independent dwelling units.
  • Must meet new Maryland state ADU guidelines as of October 2025.
  • Full construction plans signed and sealed by a MD design professional.
  • Site plan required to show placement relative to main home.
  • Must include independent living, cooking, and sleeping areas.
  • Electrical, plumbing, and mechanical permits are mandatory.

How to Get a ADU Permit in Baltimore

1

Step 1: Site Evaluation

Confirm lot has a single-family detached dwelling.

2

Step 2: Professional Plans

Have signed/sealed plans prepared by a Maryland architect.

3

Step 3: Submit Online

Apply via the PAI portal for a residential building permit.

4

Step 4: Technical Review

County reviews for zoning, building code, and utilities.

5

Step 5: Impact Fees

Pay calculated fees, including any applicable development impact fees.

Frequently Asked Questions

Maryland law now supports ADUs on land with a single-family detached dwelling.
Trade requirements often necessitate separate service for attached or detached ADUs.
Local laws being updated in 2026 will specify exact square footage limits.