Boulder, CO Accessory Structures: Shed & Carport Rules (2026)
Shed permit rules in Boulder, CO, 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
- Coverage cap
- 500 sq ft combined, rear-yard accessory structures
- Applies in
- RR, RE, RL, RMX-1 zoning districts
- Landmark/historic exception
- One added structure, up to 500 sq ft more
- Inside building envelope
- No coverage limit applies there
- Max fine
- $2,650 per violation (Sec. 5-2-4)
Summary
In Boulder's RR, RE, RL, and RMX-1 residential zones, sheds and other accessory buildings sitting in the rear yard setback area are capped at a combined 500 square feet of building coverage under Section 9-7-8(a), B.R.C. 1981, unless the property is an individual landmark or in a historic district.
(a)Maximum Building Coverage: In an RR, RE, RL or RMX-1 residential zoning district, unless the property has been designated as an individual landmark or is located within a historic district under Chapter 9-11, "Historic Preservation," B.R.C. 1981, the total cumulative building coverage of accessory buildings or structures between the principal building rear yard setback and the rear yard property line shall not exceed five hundred square feet. For a property that has been designated as an individual landmark or is located within a historic district under Chapter 9-11, "Historic Preservation," B.R.C. 1981, such total cumulative building coverage may be increased to permit the addition of one new accessory building or structure of up to five hundred square feet of coverage if such property has existing structures within the principal building rear yard setback area.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Municipal Code: Supplement 167 Update 3).
Full Breakdown
C. 1981, sets Boulder's core rule for sheds, detached garages, and other accessory structures. In the RR, RE, RL, or RMX-1 zoning districts, the total cumulative building coverage of accessory buildings or structures placed between the principal building's rear yard setback line and the rear property line cannot exceed five hundred square feet, combined across every accessory structure on the lot. C. 1981: those properties may add one more accessory building or structure of up to five hundred additional square feet of coverage if the lot already has existing structures within the rear yard setback area.
C. 1981. The chapter also regulates breezeways connecting a house to a shed or accessory building: a breezeway must stay fully open on the sides except for structural columns and the walls it connects to, cannot carry any usable floor area above it, and any portion sitting within the rear yard setback counts toward the same 500-square-foot cap. Homeowners planning a shed larger than 500 square feet, or a second accessory structure that would push the lot over that combined limit, need either a landmark/historic-district exception or a variance rather than an over-the-counter shed permit.
Violations & Fines
A shed or accessory structure that exceeds the 500-square-foot coverage cap, or that is built without the required setback compliance, is a code violation subject to Boulder's general penalty under Section 5-2-4, B.R.C. 1981: a fine of up to $2,650 per violation, up to ninety days in jail, or both, with each day of noncompliance counted separately under Section 5-2-5(b).
Frequently Asked Questions
How big can my shed be in Boulder's RL zone?
Can I build a second shed if I already have one?
Does a breezeway to my shed count against the coverage cap?
Sources & Official References
Other rules in Boulder
How Boulder compares: Shed Permit Requirements by City·Compare Boulder to another location·View the Colorado accessory structures overview
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Shed & Carport Rules in Nearby Cities
How other cities in Boulder County handle shed & carport rules.