Calvert County now has an active ADU framework with updated size, setback and parking rules. For properties under County zoning, one attached, interior or detached accessory dwelling may be possible, but homeowners still need to verify the 75% size calculation, owner occupancy, parking or waiver eligibility, and any Critical Area, septic, well or access constraints before paying for plans.
The safest way to plan is to separate County rules from municipal rules and property-specific constraints. Chesapeake Beach and North Beach administer their own zoning, so a Calvert County mailing address does not guarantee that County zoning controls the parcel. If you are inside either town, verify the municipal rule first. See our Chesapeake Beach ADU guide, or use the Maryland ADU Jurisdiction Finder to confirm the controlling jurisdiction.
Current local framework · Last verified September 13, 2026
🟢 Active — Calvert County has enacted updated ADU standards.
Ordinance 41-25 was adopted September 30, 2025 and revised the County’s ADU size and setback language. Ordinance 22-26 was adopted July 28, 2026 and added a parking-waiver path. These are enacted local rules, but parcel-specific zoning, Critical Area, septic, well and access reviews can still control feasibility.
Last verified: September 13, 2026. This page separates enacted County rules from municipal exceptions and property-specific permit conditions. Maryland ADU Guide is an independent research publication and is not legal, zoning, architectural, engineering or permitting advice.
Calvert County ADU status at a glance
| Question | Verified status |
|---|---|
| Are ADUs currently allowed? | Yes. Calvert County has an active local ADU framework for qualifying properties under County zoning. |
| What forms are allowed? | Attached, interior and detached accessory dwellings may be possible, subject to the parcel and permit review. |
| Maximum size | Up to 75% of the principal single-family dwelling’s gross floor area under Ordinance 41-25. |
| Owner occupancy | Required. An owner of the lot or parcel must occupy either the principal dwelling or the ADU, subject to the County’s temporary-absence provision. |
| Parking | Default: one additional off-street space. Ordinance 22-26 creates a waiver path where the qualifying on-street-space standard is met and Public Works approves. |
| Detached setbacks | The old primary-structure setback language was removed by Ordinance 41-25. The actual buildable location still depends on the applicable zoning district and parcel constraints. |
| Municipal exception | Chesapeake Beach and North Beach administer their own zoning. Confirm jurisdiction before relying on County standards. |
How big can an ADU be in Calvert County?
Calvert County’s 2025 amendment is important because older County materials can still surface in search results with obsolete limits such as a 1,500-square-foot detached cap or a 40% attached-unit formula. Ordinance 41-25 amended Section 18-5 so that the accessory dwelling may be no greater than 75% of the gross floor area of the single-family dwelling and must remain subordinate to it.
This is also a place where homeowners should understand the difference between the percentage and the measurement method. Maryland’s Department of Planning says HB 1466 does not itself define how the primary dwelling’s size must be measured and recommends using finished living area above grade. Calvert County’s ordinance uses the phrase “gross floor area.” Because those are not automatically the same measurement, ask Calvert County Planning & Zoning to confirm the square-footage basis it will use for your specific application before designing to the maximum.
Does Calvert County require owner occupancy?
Yes. The County’s current accessory-dwelling regulation requires an owner of the lot or parcel to occupy at least one of the two dwelling units, except for temporary absences as determined by the Zoning Officer. In practical terms, the owner can live in the main house or the ADU, but the property cannot ordinarily operate as two fully non-owner-occupied dwelling units under this provision.
Do not confuse this local zoning condition with Maryland’s statewide HOA provisions. HB 1466 limits unreasonable private restrictions on developing or renting an ADU, but it does not erase every local land-use condition or create one identical owner-occupancy rule for all Maryland jurisdictions.
What are the setback rules?
Older Calvert County text required a detached accessory dwelling to meet the setbacks of a primary structure. Ordinance 41-25 removed that language and replaced it with a requirement for adequate vehicular access as determined by the Department of Public Works. That amendment matters because Maryland HB 1466 says local side and rear ADU setbacks may not exceed the setbacks that otherwise apply to accessory structures.
That does not mean every detached ADU can automatically sit at one universal setback. The actual buildable location can still depend on the zoning district, lot configuration, easements, wells and septic areas, Critical Area restrictions, floodplain conditions and other overlays. Treat the parcel-specific zoning review as the controlling step.
How does the parking rule work after Ordinance 22-26?
The County zoning ordinance lists one off-street parking space for a “Dwelling, Accessory to a Residence.” In 2026 the County adopted Ordinance 22-26 to create a specific waiver path instead of making that requirement absolute.
Under the new provision, the Zoning Officer may waive the minimum ADU off-street parking requirement, with Department of Public Works approval, when the applicant demonstrates that enough area exists to accommodate an on-street parking space at least 7 feet wide by 23 feet long.
This is more useful than simply saying “parking is required” or “parking is not required.” The default remains one ADU space, but a qualifying property now has a defined waiver route. Maryland’s state guidance separately says jurisdictions that impose additional ADU parking must have a parking study and a waiver process.
What permits will a Calvert County ADU need?
Calvert County’s permit guidance identifies accessory apartments as a specific work type. A building permit is required, and separate electrical and plumbing/gas permits apply when that work is part of the project. Attached and detached projects also require grading review, and health review can become decisive where a private well or septic system is involved.
Properties in the Chesapeake Bay Critical Area require additional Critical Area review. Town Center and Rural Commercial locations can also trigger architectural-review requirements. These are not minor details: a parcel may satisfy the basic ADU zoning definition but still need environmental, access, wastewater or design approvals before construction can begin.
What fees should homeowners expect?
The County currently publishes a residential excise-fee schedule that lists an Apartment and Residential Accessory Dwelling Unit total of $7,750, split among school, recreation, road and solid-waste components. The County’s permit page separately lists a $25 application fee, with permit fees due after review and before issuance.
Because fee schedules can change and exemptions can depend on project type, do not use $7,750 as an all-in permit budget. Confirm the current assessment for the proposed ADU before finalizing financing or comparing contractor bids.
Critical Area, septic and well checks can change the project
Calvert County has extensive Chesapeake Bay shoreline and many properties outside public water and sewer service. For those parcels, the most important early question may not be “How large can my ADU be?” but whether the proposed additional dwelling can be supported by the existing or proposed wastewater and water system and whether the location affects a septic reserve area.
Use our Maryland ADU septic and well guide before paying for final plans if your property is not on public utilities.
Calvert County vs. Chesapeake Beach and North Beach
A Calvert County mailing address does not always mean County zoning controls the project. The incorporated towns of Chesapeake Beach and North Beach can have their own zoning authority and local ADU standards. That is why our Maryland ADU tracker separates county rules from municipal rules instead of presenting one countywide number as if it applies everywhere.
If you are uncertain which government controls your parcel, start with the Maryland ADU Jurisdiction Finder.
What Calvert County homeowners should verify before spending
That sequence is especially important in Calvert County because the current rules are materially different from older accessory-apartment handouts that may still appear online.
Primary sources used for this Calvert County guide
Calvert County Ordinance 41-25 — 2025 amendment to Section 18-5 governing accessory dwellings.
Calvert County Ordinance 22-26 — 2026 ADU off-street parking waiver amendment.
Calvert County Zoning Ordinance — current County zoning source.
Calvert County Accessory Apartment permit guidance — permit, grading, Critical Area and trade-permit requirements.
Maryland Department of Planning HB 1466 ADU FAQ — statewide size, setback, parking and October 1, 2026 implementation guidance.
Rules and official source pages reviewed September 13, 2026. Maryland ADU Guide is an independent research resource, not a government agency, law firm, architect or contractor. Verify property-specific requirements with the controlling local agency before relying on this page for design or construction decisions.
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.