Last researched: September 19, 2026. Perryville has its own zoning authority, a zoning ordinance updated December 10, 2025, and an older local category called a “Residence, Primary with Accessory Apartment.” That definition limits the second dwelling to no more than 25% of the building’s gross floor area and no more than 750 square feet. Maryland’s current ADU guidance says jurisdictions required to authorize ADUs may not set a local maximum below the state’s 75% size limit, so Perryville homeowners should not treat the legacy 25%/750-square-foot language as the final 2026 answer.
Homeowner takeaway: If your property is inside Perryville, start with the Town Planning & Zoning office. Ask for the current enacted ADU ordinance, ordinance number and effective date, then confirm whether your parcel is affected by the Chesapeake Bay Critical Area before choosing a floor plan or detached structure.
Perryville ADU planning snapshot
| Question | What we verified |
|---|---|
| Zoning authority | Perryville reviews zoning inside Town limits and issues a Town Zoning Certificate before applicable Cecil County construction permits. |
| Current zoning ordinance | Chapter 84 is posted as updated December 10, 2025. |
| Legacy accessory-apartment definition | A second dwelling within a primary residence is defined at no more than 25% of the building’s gross floor area and no more than 750 sq ft. |
| 2026 state-law issue | Maryland Planning says jurisdictions may not limit ADU size below the state’s 75% limit. |
| Critical Area rule | Perryville’s Critical Area provisions contain a separate RCA accessory-dwelling standard, including a same-sewage-system condition and 100-foot/900-sq-ft language for certain configurations. |
| Town permit | A Zoning Certificate is required before site work or improvements and for interior or exterior modifications. |
| Building authority | Cecil County issues construction permits and performs building inspections for the Town. |
| Final HB 1466-compliant ordinance | I did not locate a clearly identified final 2026 Perryville ADU ordinance in the Town materials reviewed on September 19, 2026. Confirm directly with Planning & Zoning. |
Perryville zoning applies inside Town limits
Property inside Perryville is reviewed under Town zoning rather than the zoning rules for unincorporated Cecil County. A mailing address can cross jurisdictional boundaries, so verify municipal limits before relying on either code.
For property outside Perryville, use our Cecil County ADU Rules guide. If you are unsure which government has zoning authority, use the Maryland ADU Jurisdiction Finder.
Perryville’s current posted ordinance still contains a 25% / 750 sq ft accessory-apartment definition
Chapter 84 defines a “Residence, Primary with Accessory Apartment” as a residential use that keeps the external appearance of a single-family residence while containing a second dwelling unit. Under that definition, the second unit may comprise no more than 25% of the gross floor area of the building and no more than 750 square feet.
This is useful historical and zoning context, but it creates an obvious 2026 compliance question. Maryland’s statewide ADU law defines an ADU as a secondary dwelling unit no greater than 75% of the primary single-family detached dwelling, and the Maryland Department of Planning says a jurisdiction required to authorize ADUs may not impose a lower local size ceiling.
Why the old Perryville cap should not be used as the final design limit
Take a 2,000-square-foot primary house. Perryville’s legacy 25% formula would limit an accessory apartment to 500 square feet. Maryland’s 75% ceiling reaches 1,500 square feet. The state rule does not require a homeowner to build that large, but Maryland Planning’s current guidance says the local law cannot cap the ADU below that 75% threshold.
Before choosing between a 400-, 600- or 800-square-foot layout, confirm Perryville’s current ordinance and measurement method. Our Maryland ADU size guide explains why “75% of the primary dwelling” still requires a measurement convention.
Perryville also has a separate Critical Area ADU rule
Perryville’s zoning ordinance contains Chesapeake Bay Critical Area provisions for Resource Conservation Area (RCA) land. Those provisions allow one additional dwelling unit as part of a primary dwelling under specified conditions.
The RCA language requires the additional unit to use the same sewage-disposal system as the primary dwelling. It also provides a path where the unit is within the primary dwelling or its entire perimeter is within 100 feet of the primary dwelling and the unit does not exceed 900 square feet of total enclosed area. An alternative applies to a unit located within the primary dwelling that does not increase the lot coverage attributed to the primary dwelling.
The Critical Area provision also says the additional dwelling cannot be subdivided or conveyed separately from the primary dwelling.
The Critical Area 900 sq ft figure is not a townwide answer
Do not read the RCA language as a universal Perryville ADU size cap. Critical Area regulations serve environmental and land-management purposes and can apply in addition to the Town’s general zoning law. Maryland Planning also says local ADU laws must continue to meet public-health, safety, facility-capacity and environmental requirements.
For a parcel in or near the Chesapeake Bay Critical Area, ask Perryville to identify both the general ADU rule and the Critical Area provisions that apply to the site.
Perryville requires a Town Zoning Certificate before the County construction permit
Perryville’s Planning & Zoning office states that a Zoning Certificate is required before site work or improvements to a property. The Town uses the certificate to confirm that the proposed use complies with its zoning ordinance.
The requirement is broad. Perryville says interior and exterior modifications require submission for a Zoning Certificate, and its permit FAQ lists additions, garages, renovations, changes of use and other common projects among the work that needs Town review.
After Town zoning approval, Cecil County serves as the building authority for Perryville. Construction modifications involving building, electrical or plumbing work can therefore require separate County permits and inspections.
A practical Perryville ADU permit sequence
- Confirm that the property is inside Perryville municipal limits.
- Identify the zoning district on the Town zoning map.
- Ask Planning & Zoning for the current enacted ADU ordinance and effective date.
- Confirm whether the parcel is in the Chesapeake Bay Critical Area and, if so, its designation.
- Prepare the site plan and floor-area information required for Town zoning review.
- Apply for the Perryville Zoning Certificate.
- After Town approval, submit the applicable construction application to Cecil County Permits & Inspections.
- Obtain electrical, plumbing or other trade permits as required.
- Complete required inspections before occupying the ADU.
What to ask Perryville before paying for plans
- What ordinance currently governs ADUs in Perryville?
- What is its ordinance number, adoption date and effective date?
- Has the 25% / 750-sq-ft accessory-apartment definition been amended or superseded?
- How does Perryville measure the primary dwelling for the 75% state definition?
- Which residential districts allow internal, attached and detached ADUs?
- What side and rear setbacks apply?
- What height and lot-coverage rules apply to a detached ADU?
- Does the parcel lie in the Chesapeake Bay Critical Area?
- If it is in an RCA, how do the 100-foot, 900-sq-ft and sewage-system provisions apply?
- What off-street parking requirements apply, and is there a waiver procedure?
- What water and sewer capacity review is required?
- What drawings must accompany the Town Zoning Certificate application?
- Which permits must then be obtained from Cecil County?
Perryville homeowner checklist
- Verify municipal jurisdiction.
- Check the parcel’s zoning district.
- Ask for Perryville’s current HB 1466-compliant ADU ordinance.
- Do not use the legacy 25% / 750-sq-ft definition as the final design limit without confirmation.
- Check Critical Area status.
- Confirm ADU type: internal, attached, garage conversion or new detached unit.
- Verify size, setbacks, height, lot coverage and parking.
- Confirm water/sewer or septic requirements.
- Prepare a scaled site plan or survey.
- Obtain the Town Zoning Certificate first.
- Complete Cecil County building and trade permits next.
- Do not make a non-refundable prefab or construction commitment until the parcel-specific rules are confirmed.
Perryville MD ADU FAQs
Does Perryville allow accessory apartments?
Perryville’s current posted zoning ordinance contains a category called “Residence, Primary with Accessory Apartment.” Because Maryland now requires local ADU laws that meet HB 1466, ask the Town which current ordinance and approval pathway govern a new 2026 application.
Is the Perryville ADU limit 750 sq ft?
The current posted Chapter 84 definition contains a legacy maximum of 25% of the building’s gross floor area and 750 square feet. Maryland Planning says jurisdictions may not cap ADU size below the state’s 75% threshold, so confirm the Town’s updated 2026 rule before designing to the old limit.
What if my Perryville property is in the Critical Area?
Perryville’s Critical Area provisions contain additional ADU conditions for Resource Conservation Area property, including sewage-system, location and size language. Those environmental provisions should be reviewed together with the Town’s general ADU zoning rules.
Do I need a Perryville permit before a Cecil County permit?
Yes. Perryville states that the Town Zoning Certificate is the local zoning approval. Cecil County then serves as the building authority and issues applicable construction and trade permits.
Who should I contact about a Perryville ADU?
Start with Perryville Planning & Zoning at Town Hall, 515 Broad Street, Perryville, Maryland 21903. The Town currently lists 410-642-6066 for zoning assistance.
Primary sources checked
- Town of Perryville — Chapter 84 Zoning Ordinance
- Town of Perryville — Zoning Certificates
- Town of Perryville — Zoning Map
- Maryland Department of Planning — HB 1466 ADU FAQ
- Maryland Land Use § 4-504 — Local ADU law requirements
Maryland ADU Guide is an independent research publication, not the Town of Perryville, Cecil County, the Critical Area Commission, a law firm, architect or contractor. Local rules can change during Maryland’s 2026 ADU implementation period. Confirm the current ordinance and parcel-specific requirements with Perryville before spending money on design or construction.
What to do next
Start by confirming municipal jurisdiction, zoning and Critical Area status.
- Find Who Reviews My Property.
- Gather your parcel identifier, survey, zoning district and utility information.
- Ask Perryville which current ADU ordinance and overlay rules apply.
- Continue to your planning workspace.
Planning guidance is not permit approval.