Montgomery County, MD Accessory Structures: Shed & Carport Rules (2026)
Shed permit rules in Montgomery County, MD, also referred to as storage shed, backyard shed, or accessory building regulations, set size limits, setbacks, and when a building permit is required.
Key Facts
- Size cap (Residential Detached)
- 50% of house footprint or 600 sq ft
- Size cap (Agricultural/Rural Residential)
- 50% of principal building footprint
- Cap basis
- cumulative across all accessory buildings
- Excluded municipalities
- Rockville, Gaithersburg, Poolesville, Brookeville, Barnesville, Laytonsville, Washington Grove
- Pool enclosure exception
- up to 1,200 sq ft, with conditions
Summary
In Montgomery County's Residential Detached zones, all your sheds and accessory buildings combined cannot exceed 50% of your house's footprint or 600 square feet, whichever is larger.
In Residential Detached zones, where the principal building on a lot is a detached house, the cumulative footprint of all accessory buildings on that lot may not exceed 50% of the footprint of the principal building or 600 square feet, whichever is greater. This Subsection does not apply to Section 3.3.3.C, Detached Accessory Dwelling Unit. Buildings for an agricultural use are exempt from this size restriction.
c. Where the construction of a pool enclosure would cause the cumulative footprint of all accessory buildings, including the pool enclosure, to exceed 50% of the footprint of the principal building or 600 square feet, whichever is greater, the pool enclosure may be allowed, provided:
i. the pool enclosure, not including the rafters, is translucent or transparent;
ii. the pool enclosure has a height of 8 feet or less;
iii. the pool enclosure surrounds and covers an inground swimming pool;
iv. the cumulative footprint of all other accessory buildings on the property is less than 50% of the footprint of the principal building or 600 square feet, whichever is greater; and
v. the cumulative footprint of the pool enclosure and all other accessory buildings on the property does not exceed 1,200 square feet.
B. Accessory Use Defined Accessory Use means a use that is incidental and subordinate to the principal use of a lot or site or the principal building, and located on the same lot or
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-90: Montgomery County Code contains legislation effective through May 7, 2026 | Zoning Updated Effective: April 13, 2026 | COMCOR Regulations effective as of July 1, 2026).
Full Breakdown
Montgomery County Code Section 3.7.4.A caps accessory structures, sheds, detached garages, workshops, at 50% of the principal house's footprint, or 600 square feet, whichever is greater, in Residential Detached zones; the cap is cumulative across every accessory building on the lot, not per-structure. In Agricultural and Rural Residential zones the cap is 50% of the house's footprint with no flat square-footage floor, though farm buildings are exempt. Rockville, Gaithersburg, Poolesville, Brookeville, Barnesville, Laytonsville, and Washington Grove run their own zoning and are not covered by this chapter.
Violations & Fines
Exceeding the cap can get a building permit application denied and trigger zoning enforcement requiring the accessory structure be reduced in size or removed.
Frequently Asked Questions
Does the 50%-or-600-square-foot limit apply per shed or to my whole yard?
Does this rule apply if I live in Rockville or Gaithersburg?
Sources & Official References
Other rules in Montgomery County
How Montgomery County compares: Shed Permit Requirements by City·Compare Montgomery County to another location·View the Maryland accessory structures overview
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