Short Answer
Most new garages need a building permit; in Seattle a single-story garage of 750 sq ft or less usually qualifies for a simpler subject-to-field-inspection permit. A permanently installed generator connected to the home's wiring or gas needs permits; a portable plug-in generator used temporarily does not. Connecting a portable generator to your panel needs an electrical permit for the transfer device.
Key Takeaways
- Seattle garages of 750 sq ft or less, single story, usually need only a subject-to-field-inspection permit.
- Seattle bars garages from the front 20 feet and side 5 feet of a lot in most cases.
- Generators permanently connected to a building's electrical or fuel gas system need permits; portable plug-in units do not.
- Austin issues SB 1202 backup power permits within three business days after an approved third-party review.
Quick Facts
| Garage up to 750 sq ft (Seattle) | Subject-to-field-inspection permit if single story, no roof deck, beams 14 ft or less, not in an ECA |
|---|---|
| Garage wiring or sink | Separate electrical or plumbing permit |
| Portable generator, plug-in only | No permit (Arvada, Miami-Dade) |
| Permanent standby generator | Permits for electrical and fuel gas work; Miami-Dade also requires a building permit |
| Austin backup power | SB 1202 stand-alone trade permit with third-party review |
From our city pages and each city's open permit data (refreshed October 30, 2026).
Garage Permits
Seattle says most new and remodeled garages need only a subject-to-field-inspection permit. To qualify, the garage must be 750 square feet or less, a single story without a roof deck, with beams spanning 14 feet or less, and not in an environmentally critical area. Otherwise it needs an addition or alteration permit. Wiring a garage or adding a sink needs a separate electrical or plumbing permit.
Zoning also applies. In Neighborhood Residential zones, total coverage of all structures is limited to 50 to 60 percent of the lot. You usually cannot put a garage within the front 20 feet or side 5 feet of the property; a garage in the rear yard is limited in size and height, and a side setback agreement with your neighbor may be required.
Step-by-Step: What to Do
- Size the garage and check zoning setbacks and lot coverage.
- Apply for the building permit, plus electrical and plumbing permits if needed.
- For a generator, decide on portable or permanent standby, and the fuel source.
- Prepare a site plan showing generator location, distances to property lines and openings, and the transfer switch.
- Get separate gas or plumbing permits for natural gas or propane lines.
Portable vs Standby Generators
| Setup | Permit | Source |
|---|---|---|
| Portable, plug-in, used temporarily | None | Arvada |
| Portable connected to building wiring | Electrical permit for the transfer device | Miami-Dade |
| Portable connected to fuel gas | Permit required | Arvada |
| Permanent outdoor generator | Building permit with plans by a design professional | Miami-Dade |
| Permanent, connected to electrical or gas system | Permit required; typically licensed mechanical and electrical contractors | Arvada |
Arvada notes that noise ordinance rules still apply with or without a permit.
What a Generator Application Needs
Arvada asks for a plot plan showing the generator's distance to property lines, openings into the building and other structures, plus the gas connection, electrical service equipment and transfer switch locations, manufacturer specifications with decibel rating, and gas line calculations if a line is installed. Miami-Dade requires a site plan with any permanent fuel tank, the panel and transfer switch locations, and generator specifications including a one-line diagram.
In Austin, Texas Senate Bill 1202 lets third-party professionals review and inspect home backup power, including generators, up to 600 volts for one- or two-family homes; the city must issue the permit within three business days of notice of approval. Work needing a shutdown requires a separate electrical permit, and natural gas or propane work a separate plumbing permit.
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
Do I need a permit for a portable generator?
Not if it plugs in and is used temporarily. Connecting it to your home's wiring or gas system needs a permit.
Do I need a permit for a standby generator?
Yes. A generator permanently connected to the home's electrical or fuel gas system needs permits, often electrical, plumbing and building.
Do I need a permit to build a garage in Seattle?
Yes. Most garages of 750 sq ft or less need a subject-to-field-inspection permit; larger ones need an addition or alteration permit.
Sources
Official sources checked on . Rules change; confirm with the department before you start work.
- Seattle SDCI: Garages (seattle.gov)
- Austin Development Services: Apply for a Standalone Permit (SB 1202 Backup Power) (austintexas.gov)
- City of Arvada: Generators (arvadaco.gov)
- Miami-Dade County: Generator Permits (miamidade.gov)