Short Answer
A one-story detached storage shed is usually exempt from a building permit up to a size set by the city: 120 sq ft in Seattle and Los Angeles, and 200 sq ft in Austin and Philadelphia. Exempt sheds must still meet zoning setbacks and height limits, and wiring, plumbing or a flood zone location can require a permit anyway.
Key Takeaways
- The building permit exemption for sheds ranges from 120 sq ft in Seattle and Los Angeles to 200 sq ft in Austin and Philadelphia.
- An exempt shed generally has to be one story, detached and used for storage, not as a dwelling.
- Seattle requires a Floodplain Development License even for a shed under 120 sq ft in a floodplain.
- In Philadelphia, a shed of 131 to 200 sq ft at a one- or two-family home is not permitted by zoning and needs a Zoning Board of Adjustment appeal.
- Los Angeles' exemption does not apply if the shed has heating, plumbing or electrical installations.
Quick Facts
| Seattle | No permit up to 120 sq ft roof footprint, one story, storage use, not in or near an environmentally critical area |
|---|---|
| Los Angeles | Exempt up to 120 sq ft, one story, no heating, plumbing or electrical, not in Fire District 1 |
| Austin | Exempt up to 200 sq ft and 15 ft tall, no plumbing, not in a flood hazard area |
| Philadelphia | No building permit up to 200 sq ft; zoning permit needed outside the rear yard |
| Still applies to exempt sheds | Zoning setbacks, height limits, floodplain rules and electrical permits |
From our city pages and each city's open permit data (refreshed October 30, 2026).
Shed Exemptions Compared
| City | Building permit exemption | Other conditions |
|---|---|---|
| Seattle | Roof footprint of 120 sq ft or less | Single story, detached, on a slab, piers or soil, used for storage or plants, not in or near an environmentally critical area |
| Los Angeles | Floor area of 120 sq ft or less | One story, detached tool or storage shed or playhouse, not in Fire District 1, no heating, plumbing or electrical installation, located as the zoning code allows |
| Austin | 200 sq ft or less | One story, detached, 15 ft tall or less, does not create a dwelling, no plumbing, not in a flood hazard area |
| Philadelphia | 200 sq ft or less | One story, 15 ft tall or less; zoning rules depend on size and where the shed sits |
These limits are the city versions of the model code exemption for small accessory structures, explained in Work That Does Not Need a Building Permit: IRC R105.2 Exemptions. A city can be stricter or looser than the model code, so always read your own city's rule.
Step-by-Step: What to Do
- Measure the footprint the city counts; Seattle measures the roof footprint, including overhangs.
- Check your city's size, height and use limits for an exempt shed.
- Check where the shed can sit on the lot under the zoning code, including setbacks and front or side yard rules.
- Check whether the lot is in a floodplain or environmentally critical area, which can require a permit for even a small shed.
- If you plan to add lights, outlets or water, get the electrical or plumbing permit before the work starts.
Seattle: Small Sheds, STFI Permits and Critical Areas
Seattle's Department of Construction and Inspections does not require a permit for a shed with a roof footprint of 120 sq ft or less if it is single story, detached, built on a slab, piers or soil, used for storage or plants, and not in or near an environmentally critical area (ECA). Most larger sheds need a subject-to-field-inspection (STFI) permit, the same quick permit described in Seattle STFI Permits for Decks. A full addition or alteration permit is needed if the shed is in an ECA, larger than 750 sq ft, or has beams spanning more than 14 ft.
In neighborhood residential zones, the city lists a 12 ft height limit for sheds and setbacks of 10 to 15 ft from the front lot line and 5 ft from side lot lines. A shed in a floodplain needs a Floodplain Development License even when it is under 120 sq ft.
Los Angeles and Austin: Utilities and Flood Zones End the Exemption
Los Angeles Municipal Code section 91.101.5 exempts a one-story detached tool or storage shed, playhouse or similar structure of 120 sq ft or less, but only outside Fire District 1 and only if it has no heating, plumbing or electrical installation. Running power to the shed means it is no longer exempt.
Austin's residential exemption covers a one-story detached accessory structure of 200 sq ft or less and no more than 15 ft tall, as long as it does not create a dwelling, has no plumbing and is not in a flood hazard area. For more on Austin's process, see Austin Building Permits for Home Projects.
Philadelphia: Where the Shed Sits Decides the Zoning Permit
For sheds at one- and two-family homes, Philadelphia's Department of Licenses and Inspections separates zoning from building rules:
| Shed size and location | Zoning permit | Building permit |
|---|---|---|
| Up to 130 sq ft, rear yard | Not required | Not required |
| Up to 130 sq ft, front or side yard | Required | Not required |
| 131 to 200 sq ft | Not permitted by zoning; refusal must be appealed to the Zoning Board of Adjustment | Not required |
| Over 200 sq ft | Zoning review applies | Required |
The appeal route involves a community meeting and a hearing, so a shed in the 131 to 200 sq ft range takes far longer than its size suggests. Sheds must be one story and no more than 15 ft tall, and separate electrical, mechanical or plumbing permits may be needed.
Adding Power, Water or a Living Space
An exemption covers the structure, not what goes in it. Wiring for lights or outlets usually needs an electrical permit, and a sink or toilet needs a plumbing permit. Finishing a shed as an office or guest room can turn it into habitable space with very different rules; if you want a backyard unit someone can live in, start with ADU Permit Requirements: What Homeowners Need to Know.
Building Departments in the Cities We Cover
Rules in this guide vary by jurisdiction. These are the official departments that issue residential permits in the 15 cities we track, with the city's open-data source for permit records. Each city page shows the rules for roofing, HVAC, solar, fence and deck work.
Before relying on any rule, read the department's current page or call its permit desk. Model-code sections cited here (such as IRC R105) are adopted locally, often with amendments.
Frequently Asked Questions
How big can a shed be without a permit?
It depends on the city. Seattle and Los Angeles exempt sheds up to 120 sq ft, while Austin and Philadelphia exempt sheds up to 200 sq ft from a building permit. Each city adds conditions on height, use and location.
Does an exempt shed still have to meet setbacks?
Yes. A building permit exemption does not waive zoning. Seattle lists front and side setbacks for sheds in neighborhood residential zones, and Philadelphia requires a zoning permit for a small shed in a front or side yard.
Do I need a permit to run electricity to a shed?
Usually yes. Electrical work generally needs its own permit, and in Los Angeles a shed with an electrical installation no longer qualifies for the shed exemption.
Do I need a permit for a shed in a flood zone?
Often yes. Austin's exemption does not apply in a flood hazard area, and Seattle requires a Floodplain Development License even for a shed under 120 sq ft.
Can I put a 150 sq ft shed in my Philadelphia backyard?
Not without an appeal. Philadelphia's guidance says sheds of 131 to 200 sq ft at one- and two-family homes are not permitted by zoning, so the application is refused and must go to the Zoning Board of Adjustment.
Sources
Official sources checked on . Rules change; confirm with the department before you start work.
- Seattle SDCI: Sheds (seattle.gov)
- LADBS: 2014 City of Los Angeles Amendments to the Building Code (LAMC 91.101.5) (ladbs.org)
- Austin DSD: Work Exempt from Building Permits (austintexas.gov)
- City of Philadelphia L&I: Sheds Permit FAQ (phila.gov)
- City of Philadelphia: Get a Building Permit (phila.gov)