Installing a Standby Generator?
Know the Rules Before You Buy.

Five interactive tools built for homeowners planning a generator installation — from sizing through inspection day.

Unlike a fence or a deck, a whole-house standby generator is a permanent power system. Local building departments — called the Authority Having Jurisdiction (AHJ) — require permits to verify the installation is safe, won't backfeed electricity onto utility lines during an outage, and won't violate noise or setback rules. Here is how the process typically works:

1. Size the generator correctly for your home The kW rating determines your fuel line size, transfer switch amperage, concrete pad specs, and — critically — whether your unit will comply with local noise ordinances. Oversizing costs money; undersizing means the generator trips under load. Use our Size Calculator before choosing a model.
2. Choose fuel type — it changes your permit count Natural gas generators need a gas line permit. Propane adds an LP tank permit. Diesel in California requires an additional Air Quality permit. The fuel type decision happens before the permit process, but it directly determines how many permits you need and how complex the installation will be.
3. Verify setbacks and noise compliance before purchasing This is the most commonly skipped step. If your lot is too small to meet setback requirements, or your local noise ordinance caps generators at 60 dBA and your preferred model produces 68 dBA, you may need a different model or an acoustic enclosure — decisions that affect cost before installation begins. Use the Setback Calculator and check your state's noise limits first.
4. Submit permit applications — typically 2 to 3 Most residential installations require a building permit (pad and placement), an electrical permit (transfer switch and panel), and a mechanical permit (gas line). Some jurisdictions combine these; some require four. Call your building department before applying — a 5-minute call prevents weeks of delays from an incomplete application.
5. Get HOA approval if applicable — it runs parallel to permits HOA architectural review and municipal permits are entirely separate processes. HOA review often takes 30–45 days. Start it at the same time as your permit application — not after. Use our HOA Submission Packet Template to avoid having your application returned for missing documents.
6. Pass inspections and receive final approval Most installations require at least two inspections: electrical and mechanical/gas. Each has a rough-in phase (before work is covered) and a final phase. The Inspection Prep Builder creates a personalized checklist so your installer can do a walk-through before the inspector arrives.

Generator permit rules are set at the local level, but state building codes establish the baseline. Select your state for typical permit requirements, setbacks, noise limits, and county-specific examples. View full state comparison table →

Most air-cooled standby generators run 65–68 dBA. Many residential ordinances cap generators at 60–65 dBA. The gap is real and affects your model choice. Full noise guide →