An accessory structure is a separate building on a property that supports or complements the main building. These structures are not the primary focus of the property but serve additional purposes. Common examples include garden sheds, playhouses, workshops, detached carports, or garages.

Why is This Information Important?

Understanding the rules for accessory structures is essential for property owners who want to add these buildings to their land. Following local regulations ensures that the structure is safe, functional, and compliant with zoning laws. This information helps property owners avoid potential fines, construction delays, or the need to remove a non-compliant structure. It also ensures that the new building does not negatively impact neighbors or the surrounding community.

Before adding an accessory structure to your property, you need to address the following questions:

• What is the maximum size allowed?
• What is the height of the structure?
• Is a building permit required?
• Where can the structure be located?

Distance between the Structure and Property Lines

Accessory structures, such as garden sheds, tool sheds, garages, and playhouses, must follow specific rules for height, size, and minimum distance from property lines. In some cases, you may also need a building permit to construct these structures.

Main Building Requirement

You can only build an accessory structure if there is already a main building on your property. For residential properties, this usually means there must be a house or other dwelling on the lot. Accessory structures cannot be built alone on an empty property.

Setback Requirements

Accessory structures must be placed a certain distance away from your property lines. This distance, called a setback, depends on the height of the structure and its location on the property. The table below shows the minimum setback requirements for different situations.

Minimum Distance Required between a Fire-Rated Structure and the Property Line

Building code requires accessory structures that do not have a fire rating to be a minimum of three feet from the property line regardless of the structure’s height or location.

Maximum Size

All accessory structures in a rear yard can only cover up to 25 percent of that rear yard area.

In addition, the square footage of the main building determines the maximum size of an accessory building in residential zones (except Residential Agriculture zone) as follows:

Height

Accessory structures are limited to 15 feet in height. Any structure over 10 feet in height requires a building permit.

For building permits, height is measured from the finished floor level. For determining size and location on the property, the height is generally measured from the ground.

Height of a structure with a pitched roof is measured to halfway between the peak and the eave of the pitched roof as shown below.

Example of how to measure the height of a structure

Building Permit Exemption

You need a residential building permit for your structure unless it meets all the following criteria:

• It is used as a tool shed, storage shed, playhouse or similar use which does not include vehicle storage or residential occupancy.
• The floor area is less than 200 square feet.
• The height is less than 10 feet.

You will need to submit building plans as part of the permit process. The City provides pre-approved building plans for you to download.

Example of the definition of front yard, side yard, and back yard in relation to the street, house, and property lines