Accessory Structure Rules: What You Can Build in Your Backyard
Accessory structures are secondary buildings on a property — detached garages, sheds, workshops, pool houses, and similar outbuildings. They have their own set of rules distinct from the primary dwelling, typically with smaller setbacks but also smaller size and height limits.
Definition and Common Types
An accessory structure is any structure on a lot that is subordinate to and serves the primary use of the property. This includes: detached garages, carports, sheds, workshops, garden sheds, pool houses, covered patios, gazebos, greenhouses, and detached ADUs.
Setbacks
Accessory structures typically have reduced setbacks compared to the primary dwelling. Rear setbacks of 3–5 feet are common. Side setbacks of 3–5 feet are typical. A minimum distance from the primary dwelling (often 6–10 feet for fire separation) is usually required.
Height and Size Limits
Most cities limit accessory structure height to 12–20 feet and size to a percentage of the lot area or the primary dwelling footprint. Very large accessory structures (over 1,000 sq ft) may require the same review as an ADU.
Permitted Uses
Accessory structures must be used for purposes accessory to the primary dwelling — storage, vehicles, hobbies, workshops. They cannot be used as separate dwelling units (that requires ADU approval) or commercial businesses.
Frequently Asked Questions
Can I build a workshop in my backyard?
Yes in most jurisdictions. A detached workshop is an accessory structure and is typically allowed in residential zones subject to setback, height, and size limits. Running a business from the workshop is subject to home occupation rules.
How large can my detached garage be?
Limits vary by city. Common limits are 1,000–1,200 sq ft or a percentage of the lot. Garages significantly larger than the primary dwelling may require variance approval. Check your city's accessory structure size limit.