Accessory Buildings and Sheds
Accessory building: A building, subordinate to and located on the same lot with a main building, the use of which is clearly incidental to that of the main building or to the use of the land, and which is not attached by any part of a common wall or common roof to the main building.
Accessory building requirements: An accessory building on a residential lot must be located in the rear yard. Except for a building accessory to an agricultural use, the footprint of an accessory building on a lot where the main building is a one-family detached residential dwelling must not exceed 50 percent of the footprint of the main building. Additional setbacks are required if length of the building along a rear or side lot line has a linear dimension greater than 24 feet, then the side or rear setback is increased 2 feet of additional setback for every 2 feet that the building dimension exceeds 24 feet. This does not apply to swimming pools. Accessory Setbacks can be found on the Development Standards page.
Building: A structure having one or more stories and a roof, designed primarily for the shelter, support or enclosure of persons, animals or property of any kind.
An accessory building includes but is not limited to: Detached garages, sheds, barns, portable storage containers and sea containers.
For simplicity, the terms shed and accessory building are interchangeable.
When is a Permit Required?
A building permit is required to install or construct any shed or accessory building in Montgomery County. When in residential zones, accessory buildings are only permitted on lots with an established principal use. As defined in the Montgomery County Zoning Code, an accessory building may not be attached to or have direct access from the principal structure. Regardless of the structure size, it must comply with the zoning ordinance for accessory building setbacks and location. Accessory buildings are only permitted in rear yards. If an accessory building is attached to a principal structure, it is then considered an “addition” and is reviewed and inspected under different procedures. Common, simple repairs to existing structures do not require permits however, if you are replacing an existing structure you will need a demolition permit as well.
Any electrical wiring or devices supplying electricity to any accessory building must be permitted, inspected and receive final inspection approval priot to utilization.
Shed permits are necessary to ensure compliance with code requirements. All sheds must be anchored to resist wind loads. Single story sheds with a floor area of 200 square feet or less require no structural review but do require a final inspection to verify proper location and anchorage.
Multi-story sheds and those with a floor area greater than 200 square feet, must have footings and floors designed in accordance with the International Residential Code (IRC) for One and Two Family Dwellings, 2009 edition, as amended. Additionally, these sheds may require footing and framing inspections in addition to the final.
Wind load – minimum 15 lb/ft 2 lateral load as required by the IRC or using other hardware installed in accordance with the manufacturers specifications.
Wood floor systems –must be designed to carry 40 lb/ft2 live load.
What is the Application Process?
Single-story sheds with a floor area of 200 square feet or less require a completed building permit application and two copies of a site plan. The site plan should be drawn to scale (1”=30’, 1”=20’) showing the size and location of the proposed shed, and all existing structures on the site, distances from lot lines, and drawn in accordance with an accurate boundary line survey. No construction plans are required. A zoning specialist will review these applications prior to issuance of permit.
Sheds with a floor area greater than 200 square feet and multi-story sheds require a completed building permit application, two copies of a site plan (see above requirements), and two sets of construction plans drawn to scale (min. 1/4”=1’) with sufficient clarity and detailed dimensions to show the nature and character of the work to be performed. A zoning specialist will review these applications for setback compliance. Lastly, a building plan specialist will review the application and provide code notes and inspection instructions prior to issuance of permit.
Certification of modified drawings.
Plan submittal changes which result from the suspension of a plan review must include a "Certification Of Modified Drawings". The design professional(s) responsible for the design of the project shall review all the changes from each of the disciplines and certify that the resubmitted design documents prepared under their license did, or did not, require modification as a result of any changes made.
These guidelines do not apply to “sheds” which are attached to the principal structure. When they are attached, they are considered “additions” to the principal structure and are reviewed and inspected under different procedures.
Note: On November 8, 2005, the County Council approved a special appropriation to the FY06 Operating Budget for the Department of Permitting Services for the creation of site plan enforcement inspection and review process. This special appropriation was needed to ensure that the Department of Permitting Services has sufficient resources to conduct height and setback inspections related to building permits for properties in zones that require site plan approval by the MNCPPC.