Last researched: September 19, 2026. Smithsburg already has a zoning concept that closely matches a modern accessory dwelling unit. The Town’s current Chapter 405 defines an accessory apartment as a complete second dwelling that may be located inside or added to a single-family detached house or in a separate accessory structure on the same lot.
Homeowner takeaway: Smithsburg is not starting from zero, but its current accessory-apartment framework predates Maryland’s 2025 statewide ADU law. Before paying for plans, ask the Town Planning & Zoning Department whether the existing TR/TC/SR treatment has been amended for HB 1466 and how the Town now applies Maryland’s 75% size, setback and parking rules.
Smithsburg ADU planning snapshot
| Question | What we verified |
|---|---|
| Current local term | “Accessory apartment.” |
| Internal / attached / detached? | All three are contemplated in the current definition: within, added to, or in a separate accessory structure on the same lot. |
| District treatment documented by Maryland Planning | TR and TC permitted; SR special exception. |
| Parking documented in Maryland’s ADU inventory | One space for the primary use plus one for the accessory unit. |
| Small accessory-building setback | Detached accessory buildings 100 sq ft or less: 5 ft from side/rear property lines. |
| Larger accessory-building setback | For structures over 175 sq ft, setback is tied to the longest horizontal dimension or district minimum, whichever is less. |
| Accessory-building height | 20 ft maximum under current § 405-23, subject to listed exceptions. |
| Water-allocation charge | The current code assesses each apartment/housing unit as a separate domestic equivalent unit; § 390-19 lists a $2,600 allocation charge per added DEU. |
| 2026 state-law issue | Maryland requires covered municipalities to implement ADUs under the statewide 75% size, setback and parking framework. |
Smithsburg’s definition already includes detached ADUs
The current zoning code defines an accessory apartment as a second dwelling unit that can be:
- inside an existing single-family detached dwelling;
- added to an existing single-family detached dwelling; or
- located in a separate accessory structure on the same lot as the main dwelling.
The unit must provide complete independent living facilities for cooking, eating, sanitation and sleeping.
That definition is broader than old “in-law suite” rules limited to relatives or internal conversions and is much closer to Maryland’s current ADU concept.
Maryland’s ADU inventory documents TR, TC and SR treatment
The Maryland Department of Planning’s statewide ADU ordinance inventory identifies Smithsburg as having an accessory-apartment ordinance and documents:
- TR — Town Residential: permitted;
- TC — Town Center: permitted; and
- SR — Suburban Residential: special exception.
Because that inventory predates Maryland’s 2025 HB 1466 implementation period, homeowners should still confirm the current use table with Smithsburg Planning & Zoning before relying on it for a 2026 application.
Smithsburg’s current eCode still retains the accessory-apartment definition, and Chapter 405 remains the controlling zoning chapter.
Smithsburg’s current accessory-building setbacks matter for detached units
Current § 405-21 gives different rules based on accessory-building size.
A completely detached accessory building of 100 square feet or less may occupy a required side or rear yard but must remain at least 5 feet from the side or rear property line.
For a detached accessory building larger than 175 square feet, the required side/rear distance is the lesser of:
- the structure’s longest horizontal dimension; or
- the minimum distance required by the zoning district.
A permanently placed accessory building also cannot occupy a recorded easement.
Maryland’s current ADU law says a local government may not impose ADU side or rear setbacks more restrictive than its existing accessory-structure setbacks. That makes § 405-21 an important benchmark for a detached Smithsburg ADU.
Accessory buildings are generally capped at 20 ft
Current § 405-23 says accessory buildings and structures may not exceed 20 feet in height, subject to listed exceptions such as farm structures, towers, chimneys and similar features.
For a detached ADU, ask whether the Town applies this 20-foot limit directly or whether a newer HB 1466 amendment establishes a separate ADU height rule.
Parking is another rule that needs a 2026 check
Maryland’s statewide ADU inventory documents Smithsburg’s accessory-apartment parking as one space for the primary use and one space for the accessory unit.
Maryland’s current HB 1466 framework now limits additional ADU parking requirements. If a jurisdiction imposes extra off-street parking specifically because of an ADU, it must complete the required parking study and provide a waiver process.
For a current Smithsburg application, ask:
- whether one additional ADU space is still required;
- whether the Town completed the required parking study;
- whether on-street parking can be considered; and
- what waiver procedure applies.
Water allocation can add a real cost to a Smithsburg ADU
Smithsburg’s water code is unusually specific. § 390-19 says a water-allocation benefit charge applies to conversions, alterations or additions to residential property already connected to the Town water system.
The current code treats each residence, apartment or housing unit as a separate domestic equivalent unit (DEU) for allocation purposes.
The current charge listed in § 390-19 is $2,600 per additional domestic equivalent unit.
That does not mean every ADU project will automatically owe exactly $2,600 in total utility costs. Smithsburg also has separate water/sewer connection and usage charges, and the Town makes the initial DEU assessment after consulting with the user.
Before final design, ask Public Works or Planning:
- whether the ADU creates an additional DEU;
- whether the existing water service has capacity;
- whether a separate meter or connection is required;
- whether sewer capacity or hookup charges apply; and
- what current fees apply on the application date.
Smithsburg’s current hookup fees are separate from the allocation charge
The Town’s current water and sewer code lists separate hookup or connection fees in addition to water-allocation charges.
For in-Town customers, the current code lists:
- $2,500 for a water hookup; and
- $3,000 plus the current County hookup/connection fee for sewer.
A project that can reuse existing service may be treated differently from one needing a new connection. Get a written utility determination before budgeting the project.
Maryland’s 75% rule is broader than Smithsburg’s old framework may have assumed
Maryland now defines an ADU as a secondary dwelling unit on the same lot as a primary single-family detached dwelling and allows the ADU to be up to 75% of the size of the primary dwelling.
The Maryland Department of Planning says jurisdictions subject to HB 1466 may not impose a lower local maximum.
Smithsburg’s current eCode definition itself does not state a modern 75% formula. Before choosing a floor plan, ask the Town:
- what maximum size applies now;
- how the primary dwelling is measured;
- whether attached and detached units use the same calculation; and
- whether any absolute square-foot cap remains in the current ordinance.
Use our Maryland ADU size guide to understand the statewide calculation before applying it locally.
Do not assume Washington County zoning controls inside Smithsburg
Smithsburg has its own municipal zoning authority, zoning map, Planning Commission and Planning & Zoning Department.
Washington County health, building, utility or other departments may still be involved in specific parts of the permit process, but the Town’s zoning code should be checked first for property inside Smithsburg.
Town Planning & Zoning should be involved before construction
Smithsburg’s Planning & Zoning Department handles local zoning administration. The Town also says building intentions should be presented early enough for application, approval and permit processing.
For an ADU, ask which approvals are required for:
- zoning use approval;
- an internal conversion;
- an attached addition;
- a detached accessory apartment;
- site-plan review;
- building inspections;
- electrical and plumbing permits;
- water allocation; and
- final use and occupancy.
We did not find a separately identified 2026 ADU amendment in the current eCode new-law display
Smithsburg’s current eCode Chapter 405 display shows a 2025 zoning amendment as its newest listed zoning law, while the accessory-apartment definition remains in the code.
During this September 19, 2026 research pass, I did not locate a separately identified 2026 HB 1466 ADU amendment in the current public code materials surfaced.
That does not prove none has been adopted or is pending. With Maryland’s October 1 deadline approaching, ask the Town directly whether the accessory-apartment provisions have been amended for HB 1466 compliance.
What to ask Smithsburg before paying for ADU plans
- Has Smithsburg adopted a 2026 HB 1466 ADU amendment?
- Are accessory apartments still permitted in TR and TC and special exceptions in SR?
- What maximum ADU size applies now?
- How does the Town calculate Maryland’s 75% size limit?
- Are internal, attached and detached units all still allowed?
- What side and rear setbacks apply to a detached ADU over 175 sq ft?
- Does the 20-ft accessory-building height limit apply?
- What parking requirement and waiver process apply?
- Has the Town completed the required ADU parking study?
- Will the project be assessed an additional water DEU?
- What water-allocation benefit charge applies?
- Will a new water/sewer hookup be required?
- What Town and Washington County building/trade approvals are required?
Smithsburg homeowner checklist
- Confirm the property is inside Smithsburg municipal limits.
- Check whether the parcel is SR, TR, TC or another district.
- Ask Planning & Zoning for the current ADU/accessory-apartment ordinance.
- Confirm whether the existing district treatment has changed for HB 1466.
- Determine whether the ADU will be internal, attached or detached.
- Verify the current legal size and measurement method.
- For a detached unit, confirm the § 405-21 setback calculation.
- Check height, easements and lot configuration.
- Confirm parking and any waiver process.
- Ask whether a second DEU and the $2,600 allocation charge apply.
- Confirm any water/sewer hookup charges before budgeting.
- Map zoning, building and trade permits before construction.
Smithsburg MD ADU FAQs
Does Smithsburg allow detached ADUs?
Smithsburg’s current definition of “accessory apartment” expressly includes a second dwelling in a separate accessory structure on the same lot as the main dwelling. Confirm the current zoning-district and 2026 HB 1466 standards before applying.
Which Smithsburg zoning districts allow accessory apartments?
Maryland’s statewide ADU ordinance inventory documents accessory apartments as permitted in Town Residential (TR) and Town Center (TC), with special-exception treatment in Suburban Residential (SR). Confirm that district treatment with the Town for a 2026 application.
What are Smithsburg’s accessory-building setbacks?
A detached accessory building of 100 sq ft or less must remain at least 5 ft from side and rear property lines. For a structure over 175 sq ft, § 405-21 uses the lesser of the structure’s longest horizontal dimension or the district minimum setback.
How tall can a detached accessory structure be?
The current code uses a 20-ft maximum for accessory buildings and structures, subject to listed exceptions. Confirm whether Smithsburg applies that directly to a detached ADU.
Can a Smithsburg ADU trigger a water fee?
Yes. The current water-allocation code treats each residence, apartment or housing unit as a separate domestic equivalent unit and lists a $2,600 allocation charge per additional DEU for qualifying conversions, alterations or additions.
Who should I contact about a Smithsburg ADU?
Start with the Town of Smithsburg Planning & Zoning Department at 21 West Water Street, Smithsburg, Maryland 21783. The Town lists 301-824-7234 and info@townofsmithsburg.org.
Primary sources checked
- Town of Smithsburg — Chapter 405 Zoning
- Town of Smithsburg — § 405-7 Definitions / Accessory Apartment
- Town of Smithsburg — § 405-21 Accessory Buildings and § 405-23 Height
- Town of Smithsburg — Water System Allocation Fees
- Town of Smithsburg — Water/Sewer Rates and Hookup Fees
- Town of Smithsburg — Planning & Zoning Department
- Maryland Department of Planning — ADU Ordinance Inventory
- Maryland Department of Planning — HB 1466 ADU FAQ
Maryland ADU Guide is an independent research publication, not the Town of Smithsburg, Washington County, a law firm, architect or contractor. This page reports Smithsburg’s current accessory-apartment definition, accessory-structure standards, water-allocation rules and Maryland Planning’s documented zoning treatment, then compares them with the state’s 2026 ADU framework. Confirm any newer amendment and parcel-specific requirements with the Town before spending money on design or construction.
What to do next
Confirm Smithsburg’s current accessory-apartment district treatment and utility charges before choosing an ADU layout.
- Confirm who reviews the property.
- Ask Smithsburg Planning & Zoning for the current ADU/accessory-apartment ordinance.
- Ask whether the project creates an additional water DEU or hookup charge.
- Continue to the Maryland ADU planning tools.
Planning guidance is not permit approval.