Short answer
Do I need a permit to build a garage in Howard County?
Yes. Only one-story sheds under 200 square feet are exempt from a building permit. Attached garages are filed as residential additions.
| Project | Howard County permit? |
|---|---|
| Detached garage | Yes, building permit |
| Attached garage | Yes, residential addition permit |
| One-story shed under 200 sq ft | Not required |
| Wiring, plumbing, gas or HVAC | Yes, separate trade permits |
| Converting a garage to living space | Yes, alteration permit; ADU rules for a separate unit |
1. The size cap on detached garages
Howard County caps the total floor area of all detached accessory structures on a single-family lot, garages and sheds together:
| Lot | Total detached accessory space |
|---|---|
| In the planned public water and sewer service area | 600 sq ft |
| RC or RR zone, 2 acres or less | 1,200 sq ft |
| RC or RR zone, over 2 acres | Higher limits, revised in 2026: check with Planning and Zoning |
A typical two-car garage of 24 by 24 feet is 576 square feet, which uses almost the whole 600-square-foot allowance on a suburban lot, including any existing shed. Pools and farm buildings on a qualifying farm don't count. Going over the cap needs a variance from the Hearing Examiner. An attached garage is part of the house, so it doesn't count toward this cap but must meet the house setbacks.
2. Setbacks and placement
Accessory building setbacks depend on your zoning district and can differ a lot (recent county variance cases involved 10-foot and 30-foot side setbacks), so look up your district in the Howard County Zoning Regulations before you design. Garages that don't fit need a variance, and the Hearing Examiner both grants and denies them. Detached accessory buildings can't hold a full bath, a full kitchen or living space unless they are an approved accessory dwelling unit.
3. Columbia and the historic districts
In Columbia, covenant approval from your village comes before the county permit. In Ellicott City and Lawyers Hill, the Historic Preservation Commission reviews new buildings. See our Howard County permit guide.
4. Applying, inspections and fees
Apply through the county's online permit portal with a plot plan drawn to scale showing every structure and its distance to the property lines, and construction drawings: floor plan, elevations, wall bracing and a cross-section. Lots on a well or septic system need Health Department approval first. Inspections can include footings, slab, framing, insulation and final, plus separate electrical, plumbing, gas and HVAC inspections, depending on the build. Howard County charges by square footage or flat fees rather than project value: a residential addition has a $50 filing fee plus a per-square-foot fee, with a 10% technology fee on top, and the county's building excise tax of $1.96 per square foot applies to new residential construction and additions.
5. Converting a garage or adding an ADU
Converting an attached garage to living space is an alteration that needs a permit. Under the zoning change that took effect in April 2026, Howard County allows accessory dwelling units attached to the house, inside it, or in a detached building, including an existing detached structure. A detached ADU has to meet the district's accessory setbacks and size limits and needs a permit from the Department of Planning and Zoning; confirm the current size and parking rules with the county before you design. See our ADU guide for how in-law suites work in practice.
