Build Your ADU in Howard County, MD
Makara ADU designs, permits and builds accessory dwelling units to Howard County’s rules, and builds nothing else.
- ADU max size
- 75% of the principal dwelling exterior footprint · Max 2 bedrooms
- Minimum lot size
- No minimum
- Owner occupancy
- Required
- Off-street parking
- Three off-street spaces per ADU (exceptions allowed)
- Allowed by
- Right, in permitted zones
- Rules current as of
- 2026-04-08
- Licensed & Insured in Maryland (MHIC 151479)
- Howard County ADU Specialists
- Full-Service: Design → Permits → Build
- Free Property Eligibility Assessment
Can you build an ADU in Howard County, MD?
Howard County ADU Guidelines
The rules that decide whether, and what, you can build. The table below carries the specifics.
75% of the principal dwelling exterior footprint
75% of the principal dwelling exterior footprint · Max 2 bedrooms
Permitted by right
All residential zones. No minimum lot size.
Accessory-Structure Setbacks
Per zoning district accessory structure standards
Off-street spaces
Three off-street spaces per ADU (exceptions allowed)
Owner must live on site
Not permitted as a short-term rental · one ADU per single-family lot
Governing ordinance
Howard County CB3-2026 (effective April 8, 2026)
Check Your Address
Run our free eligibility check and get Howard County’s rules applied to your exact lot in about a minute.
Check my property →| Requirement | Howard County standard |
|---|---|
| Allowed by | Right, in permitted zones |
| Minimum lot size | No minimum |
| Permitted zones | All residential zones |
| Maximum size | 75% of the principal dwelling exterior footprint · Max 2 bedrooms |
| Setbacks | Per zoning district accessory structure standards |
| Parking | Three off-street spaces per ADU (exceptions allowed) |
| Owner occupancy | Required |
| Garage or basement conversion | Allowed |
| Who may live there | Not permitted as a short-term rental · one ADU per single-family lot |
| Ordinance | Howard County CB3-2026 (effective April 8, 2026) |
| Rules current as of | 2026-04-08 |
The Howard County ADU Permit Process
Makara ADU handles this entire process from design to move-in, full turn-key.
- 01
Zoning & Eligibility
Confirm the lot holds a single-family detached dwelling and identify the zoning district's accessory-structure setbacks. Makara ADU does this free with our property eligibility checker.
- 02
Design & Drawings
Architectural and structural plans to the county's residential code, sized to 75% of the house's exterior footprint, with three off-street spaces planned or an exception requested.
- 03
ADU Application (County)
File the plans with the Department of Planning and Zoning. Makara ADU handles this for its clients.
- 04
Building Permits & Build
Building and trades permits from the county; construction proceeds with county inspections along the way.
- 05
Final Inspection & Occupancy
The county's final inspection and use-and-occupancy approval, then keys in hand, ready to occupy or rent while the owner remains in residence.
Howard County’s ADU Specialists
We don't build everything. We build ADUs. Based in Gaithersburg, we work with local permitting offices every week and know how each jurisdiction's rules shape what can be built.
Local Rules, Known Cold
Every jurisdiction we serve has its own size limits, setbacks, parking and occupancy rules. We track them, and the eligibility checker on this page runs on that same data.
One Contractor, Start to Finish
Architecture, engineering, permits, foundation, framing, MEP, sprinklers, finishes, and the rental license — Makara ADU manages everything under one contract. No coordinating separate architects, engineers, and builders.
Fixed-Price Proposals
We quote your project in full before a shovel goes in the ground. No surprise change orders mid-construction — we plan for lot coverage, stormwater, and utility connections up front.
Built for Aging in Place & Family
Most of our Howard County clients build to keep aging parents or adult children close. We design single-floor, accessible units that work beautifully today and adapt gracefully over time.
ADU Types We Build in Howard County
Most jurisdictions allow more than one ADU configuration. We help you choose the right one for your lot, your zone and your goals.
Detached Backyard Cottage
A fully independent structure in your backyard with its own entrance, kitchen and bath. The most flexible option, and the one most people picture. Size and placement follow the rules in the table above.
Attached Second Home
Add an attached ADU with its own separate entrance, kitchen, and bath. Makara ADU will collaborate with you to design the space to be functional to meet your needs while creating an aesthetically pleasing space that will add value to your life, family and your home.
Basement and Garage Conversions
Convert an existing garage or basement into a legal, licensed ADU — the most cost-effective path to added living space, and often faster to permit than new construction.
ADUs We’ve Built Recently
A sample of ADUs we have completed.
Howard County ADU FAQ
Is there a minimum lot size for an ADU in Howard County?
No. CB3-2026 eliminated lot-size minimums for accessory dwelling units.
How big can an ADU be in Howard County?
Up to 75% of the main house's exterior footprint, with no more than two bedrooms.
Can I rent out an ADU in Howard County?
Long-term, yes, provided the owner lives in the house or the unit. Short-term rental is not permitted.
How much parking is required?
Three off-street spaces per ADU under CB3-2026, up from one previously. Exceptions are allowed.
When did the new rules start?
CB3-2026 was signed on February 6, 2026 and took effect on April 8, 2026.
Is Your Howard County Property Eligible for an ADU?
Use our free eligibility checker to find out in about a minute, and get a personalized report sent to your inbox.