An ADU permit package in Maryland is not one universal form. Zoning, building, health and utility review can be handled differently by each county or municipality. The useful approach is to assemble the property evidence first, then confirm the exact submission list with the authority that reviews your address.
Maryland’s ADU law requires local governments to authorize ADUs under the statewide framework by October 1, 2026, while preserving public-health, safety, building-code and adequate-public-facilities review.
Start with the reviewing jurisdiction
Before collecting drawings, identify who controls zoning and who handles building permits. Do not rely on the postal city alone. Start with the Maryland ADU Jurisdiction Finder, then confirm the current application requirements with the office shown for the property.
The homeowner’s pre-application file
These are not promises that every jurisdiction will require every item. They are records that answer common questions before or during ADU review.
1. Property identification
- Street address
- Tax account or parcel number
- Owner name
- Current zoning district
- Municipality, if applicable
2. Survey or recorded plat
A current survey or usable recorded plat helps establish property lines, existing structures and the base information needed to discuss setbacks and placement. For a detached or expanded ADU, do not estimate property lines from fences or online aerial imagery.
3. Existing-home size evidence
Maryland’s ADU definition uses a 75% size relationship to the primary single-family detached dwelling. MDP recommends finished living area above grade because the statute itself does not specify the measurement method. Keep the source you used and confirm the local implementation before relying on the number.
Use the Maryland ADU size measurement guide, then test the figures in the Property Feasibility Checker.
4. Concept or site plan
At the early stage, a concept plan should make the proposal understandable: existing house, proposed ADU or conversion area, property lines, access, parking if relevant, and major site constraints. Final submission requirements can be more detailed. See the Maryland ADU Site Plan Guide.
5. Building drawings
The building department may require floor plans, elevations, sections, structural information and code details appropriate to the project. Interior conversions, garage conversions, additions and detached new construction do not create identical drawing needs. Maryland’s statewide ADU law does not replace applicable building-code review.
6. Water and wastewater records
For public systems, ask the serving utility whether the project needs capacity review, a connection change, meter work, fees or another approval. For septic, obtain the approved septic design or bedroom rating before assuming the system can serve an added dwelling. For a private well, ask the health/environmental office about capacity and required separation distances.
See the Maryland ADU septic and well guide.
7. Overlay and environmental checks
- Critical Area status where applicable
- Floodplain or mapped environmental constraints
- Historic property or district status
- Other locally mapped overlays that affect development review
Do not guess. Use the official map or record and keep a copy or link with your project file.
8. HOA, deed and recorded covenants
Obtain the actual recorded language rather than relying on a neighbor’s summary. Maryland law limits unreasonable private restrictions on ADUs in covered circumstances, but that does not make every covenant irrelevant, and short-term-rental restrictions are a separate issue. See the Maryland ADU HOA guide.
What not to pay for too early
Before commissioning a full construction set, resolve the issues that could change the concept: jurisdiction, primary-dwelling framework, size, placement, septic/well constraints and major mapped overlays. A polished drawing does not cure a site or authority problem.
Who handles each part?
If zoning, building, Environmental Health and utility review are starting to blur together, use Who Reviews a Maryland ADU? to see what each office can establish—and what it cannot.
A practical permit-preparation sequence
- Identify the reviewing authority.
- Run a property feasibility screen.
- Collect the survey/plat and primary-home measurement source.
- Resolve water/wastewater and mapped constraints.
- Confirm the jurisdiction’s current ADU submission checklist.
- Prepare the drawings and supporting documents that checklist actually requires.
- Keep copies of submitted plans, comments, revisions and approvals in one project file.
Maryland sources
MDP HB 1466 FAQ · Maryland Land Use § 4-504 · MDP Model Local ADU Ordinance & Assessment Tool
Reviewed September 25, 2026. Always use the current checklist issued by the office reviewing your property.
What to do next
Start by finding the office that reviews your property. A mailing city or a county guide does not establish your parcel’s authority.
- Find Who Reviews My Property.
- Obtain your parcel identifier, survey, floor plans and utility records.
- Ask the reviewing office which current rules, supporting documents and approvals apply.
- Continue to your planning workspace.
Enable JavaScript to prepare a downloadable next-step brief. Planning guidance is not permit approval.