Last researched: September 18, 2026. St. Michaels has a detailed municipal ADU code, but several published limits now need to be read alongside Maryland’s newer statewide ADU law. Before buying plans, confirm which standard the Town is currently administering.
Quick answer: St. Michaels Code §340-58 allows one ADU on the same lot as a detached single-family home. It recognizes an internal conversion, an addition, a stand-alone unit, or an addition to an accessory building such as a garage. The published code also contains an 800-square-foot/50% size limit, owner-occupancy requirement, two-person occupancy cap, short-term-rental ban and detailed design standards. Maryland HB 1466 creates important 2026 compliance questions around some of those provisions.
St. Michaels ADU rules at a glance
| Question | Published Town rule / planning note |
|---|---|
| Eligible home | Same lot as a detached single-family dwelling; not a two-family dwelling, townhouse or multifamily dwelling under §340-58. |
| Number | One ADU per lot. |
| Creation | Internal conversion, addition to home, stand-alone unit, or addition to an accessory building such as a garage. |
| Published size cap | 50% of principal dwelling living area or 800 sq ft, whichever is less; verify current 2026 HB 1466 implementation. |
| Owner occupancy | Published code says owner occupies the principal unit as primary residence. |
| Occupancy | Published code caps ADU occupancy at two persons. |
| Short-term rental | Expressly prohibited for the ADU. |
| Kitchen/bath | Complete kitchen and bathroom facilities separate from the principal dwelling. |
| General accessory setbacks | 3-ft side / 5-ft rear under §340-101, with special rear-alley treatment; confirm application to the specific ADU. |
1. First confirm you are actually inside St. Michaels
Do not use Talbot County’s ADU dimensional rules simply because the mailing address says St. Michaels. Inside Town limits, St. Michaels Planning & Zoning administers Chapter 340. If you are outside Town limits, start with our Talbot County ADU guide. If unsure, use the Maryland ADU Jurisdiction Finder.
2. Four ways St. Michaels says an ADU can be created
§340-58 is unusually specific. An ADU may be created by converting existing living area, adding floor area to the home, constructing a stand-alone unit, or adding onto an existing accessory building, with a garage-related apartment given as an example. An internal conversion may therefore be more practical than a backyard cottage on a constrained lot.
3. The published 800-sq-ft limit is a major 2026 verification point
The published §340-58 caps an ADU at 50% of the principal dwelling’s living area or 800 square feet, whichever is less. Maryland’s HB 1466 framework defines an ADU as up to 75% of the size of the primary single-family detached home, and Maryland planning guidance says covered jurisdictions may not impose an ADU size limit below that 75% threshold.
Example: for a 1,600-sq-ft primary home, the published Town formula yields 800 sq ft; 75% is 1,200 sq ft. A 400-sq-ft difference is too large to ignore when commissioning plans. Use our 75% ADU Size Calculator for planning, then confirm the currently administered Town standard.
4. Detached ADU setbacks: useful numbers, but verify the parcel
For residential accessory structures generally, §340-101 states a 3-foot minimum side setback and 5-foot minimum rear setback. For a residential lot whose rear lot line abuts an alley, customary accessory uses may be permitted without regard to the rear-yard requirement if they do not obstruct the alley or reduce access.
Those numbers are valuable for early feasibility, but an ADU also has its own standards and a parcel can have other constraints. Confirm the exact treatment before placing a detached ADU on a survey.
5. Additions have detailed design-matching rules
If the ADU adds floor area to the house, §340-58 addresses exterior finish materials, roof pitch, trim, window proportions/orientation and eave projection. In plain English, the addition is expected to visually relate to the principal home. Discuss exterior design before paying for finished architectural drawings.
6. Even the location of the ADU entrance matters
The published rule says only one entry may be on the front façade of the principal dwelling facing the street unless additional front-façade entrances existed before the ADU was created. For an internal conversion, this can materially affect the floor plan and independent access.
7. Owner occupancy can change your rental strategy
The published code requires the owner to occupy the principal unit as a primary residence and says the owner may not receive rent for the owner-occupied unit. If your plan is to live in the ADU and rent the original house, do not assume the published rule permits it. Verify the currently effective 2026 language with Planning & Zoning.
8. Can you Airbnb a St. Michaels ADU?
The published ADU code says no. §340-58 expressly states that an ADU may not be used for a short-term rental. Do not confuse “ADU allowed” with “vacation rental allowed”; they are different land-use questions.
9. The published occupancy cap is two people
§340-58 limits ADU occupancy to no more than two persons. That can materially affect multigenerational plans. Because this is a locally restrictive provision during the 2026 statewide transition, confirm its current status before relying on it for long-term household planning.
10. Historic District review can create a second design layer
St. Michaels Planning & Zoning supports a Historic District Commission in addition to the Planning Commission and Board of Zoning Appeals. If the property is subject to historic controls, exterior work can involve another review track. Visible additions, detached structures, exterior materials, windows and roof forms should be checked before final design.
11. Critical Area and waterfront constraints matter
The Town zoning code incorporates Chesapeake Bay Critical Area requirements. Waterfront, wetland or otherwise environmentally constrained properties can therefore have restrictions not apparent from the basic 3-foot/5-foot accessory-structure setbacks. Ask whether Critical Area, floodplain, buffer or lot-coverage rules affect the proposed location.
12. St. Michaels homeowner roadmap
- Confirm Town jurisdiction.
- Confirm the principal dwelling qualifies under the effective ADU rule.
- Ask what HB 1466 implementation standard is effective, especially for size.
- Choose the ADU type: internal, addition, detached or garage-related.
- Locate a survey and check lot lines, structures, alleys and easements.
- Verify setbacks and environmental constraints.
- Check Historic District review where applicable.
- Confirm parking; §340-58 points to the Town parking article.
- Confirm owner-occupancy and occupancy limits.
- Keep short-term-rental plans separate; the published ADU rule prohibits STR use.
- Only then commission final plans.
St. Michaels ADU FAQs
Can I build a backyard cottage?
The published code expressly recognizes a stand-alone ADU on the same lot as a detached single-family dwelling. The actual location still depends on setbacks, zoning, environmental constraints, historic review where applicable, and building/fire-safety requirements.
Can I convert my garage?
Potentially. §340-58 recognizes an ADU associated with an existing accessory building and gives a garage-related apartment as an example. Confirm whether the existing garage footprint, setbacks, structure and utilities can support legal residential occupancy.
Can I create an ADU inside my house?
Yes as a recognized ADU type: the code allows conversion of existing living areas. The ADU must have complete kitchen and bathroom facilities separate from the principal dwelling and meet building/fire-safety requirements.
How big can it be?
The published local code says 50% of the principal dwelling’s living area or 800 sq ft, whichever is less. Maryland’s newer HB 1466 framework creates a significant 2026 conflict with that cap. Confirm the standard the Town is currently applying before designing to either number.
Does Maryland’s 75% rule guarantee that much buildable area?
No. Maximum size does not guarantee the lot can accommodate it. Setbacks, lot coverage, environmental restrictions, building code and design standards still matter.
How close can a detached ADU be to the property line?
The general residential accessory-structure rule states 3 feet at the side and 5 feet at the rear, with special treatment for rear-alley lots. Have the Town confirm those setbacks for the actual ADU proposal.
My backyard has an alley. Does that help?
Potentially. §340-101 gives special rear-yard treatment to customary accessory uses on residential lots abutting an alley, provided the structure does not obstruct or reduce alley access. Ask the Zoning Inspector how it applies to your ADU.
Can I Airbnb the ADU?
Not under the published ADU rule. §340-58 expressly prohibits short-term-rental use.
Can more than two people live there?
The published provision caps occupancy at two persons. Verify whether this remains unchanged under 2026 implementation.
Can I have two ADUs?
The published Town code says no more than one ADU per lot.
Can I live in the ADU and rent my main house?
Do not assume so. The published code requires the owner to occupy the principal unit as the primary residence. Verify whether the Town’s 2026 implementation changes that provision.
Do I need a separate kitchen and bathroom?
Yes. The published ADU rule requires complete kitchen and bathroom facilities separate from those of the principal dwelling.
Will a historic St. Michaels property need extra review?
It can. If the property or proposed work is subject to Historic District requirements, exterior changes may require Historic District Commission review in addition to ordinary zoning/building steps.
What should I do before buying plans online?
Confirm jurisdiction, current 2026 size rule, ADU type, setbacks, Critical Area/flood constraints, historic review, parking and owner-occupancy requirements first. A stock plan is useful only after you know its footprint and exterior treatment can work on the parcel.
Primary sources checked
- St. Michaels Code §340-58 — Accessory Dwelling Unit
- St. Michaels Code §340-101 — Accessory Structures
- Town of St. Michaels — Planning & Zoning
- Maryland Department of Planning — HB 1466 FAQ
Maryland ADU Guide is an independent research publication, not the Town of St. Michaels, a law firm, architect or contractor. Rules can change and parcel-specific conditions matter. Confirm requirements with the Town before making design, permitting or financial 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.