The popularity of Accessory Dwelling Units (ADU) is increasing across California, especially in cities such as San Diego where there is a high demand for housing. But the construction of ADU is not limited to design and construction only. Homeowners need to understand electrical requirements, fire safety codes, solar rules, and how to pick the right builder.
This blog will cover:
- Electric panels and service upgrades for ADUs
- Fire ratings and safety requirements
- How to choose the right ADU company in San Diego
- Whether solar is required for ADUs
Electric Panels and Service Upgrades for ADUs
One of the first questions homeowners ask is: Can my existing electric panel handle the power needs of a new ADU?
Why Electric Panels Matter
- Most older homes in California have 100-amp panels, which may not be enough once you add an ADU with its own kitchen, HVAC, and appliances.
- A modern ADU often requires 200-amp service or more to safely power all devices.
When to Upgrade
- If your ADU has a full kitchen and separate HVAC system, an upgrade is almost always required.
- Separate ADU usually requires a sub -nale, which connects to the main panel of the house.
- If you are planning to add an EV charging station or solar battery, upgrading now can avoid future troubles.
👉 For reference, San Diego Gas & Electric (SDG&E) provides details on service upgrades and permits.
Fire Ratings & Safety Requirements for ADUs
Since ADU are independent living units, they have to follow the California Building Standard Code (Title 24) for security.
Key Fire & Safety Rules:
- Fire Separation Walls
- Detached ADUs must have a 1-hour fire-rated wall if they are within 5 feet of the property line.
- Attached ADUs often require fire-rated assemblies between units.
- Smoke & Carbon Monoxide Detectors
- Every ADU must include interconnected smoke alarms and CO detectors in sleeping and living areas.
- Fire Sprinklers
- Not all ADUs require sprinklers. If the primary home has them, the ADU usually must as well.
- In areas classified as wildfire hazard zones, sprinklers may be mandatory.
- Egress Windows & Doors
- Bedrooms must have at least one emergency escape window.
- Minimum clear opening: 5.7 square feet.
- Accessibility & Safety Codes
- ADUs must follow energy efficiency, ventilation, and earthquake safety rules under California codes.
👉 You can review ADU fire safety codes in the California Department of Housing and Community Development.
How to Choose the Right ADU Company in San Diego
With dozens of contractors advertising ADU services, finding the right builder is critical.
Steps to Pick the Best ADU Company:
- Check Licensing & Insurance
- Verify the contractor’s license on the California Contractors State License Board (CSLB) website.
- Look at Past ADU Projects
- A company that has built multiple ADUs in San Diego will understand local zoning and permit requirements.
- Compare Quotes Carefully
- Don’t just look at the lowest bid. Review line items like design, permits, utility hookups, and finishes.
- Ask About Timeline & Subcontractors
- Delays are common in ADU projects. Choose a builder with in-house crews and a solid reputation for meeting deadlines.
- Customer Reviews & References
- Check Google reviews, Yelp, and ask for references from past ADU clients in San Diego.
👉 The City of San Diego also has an ADU Permit Guide to help homeowners choose legitimate builders.
Do I Need Solar on My ADU?
Solar rules for ADUs can be confusing. California has strict energy efficiency standards, but not every ADU is required to have solar.
When Solar is Required:
- If you are creating a new separate ADU larger than 800 square feet, a solar panel is usually required under the title 24 energy code.
- For attached ADUs or garage conversions, solar may not be required since they share power with the main house.
- Local jurisdictions (like San Diego) may have additional requirements if the property already uses solar.
Costs & Benefits:
- Installing solar energy during construction is often cheaper than adding it later.
- With the high energy rates of San Diego, solar panels can reduce long -term utility bills.
- By adding solar energy, you can also be eligible for discounts and your ADU fare can also increase attraction.
👉 For full requirements, check the solar standards of California Energy Commission.
Final Thoughts
Building an ADU in San Diego requires more than just a good floor plan. You need to plan for:
- Electric panel upgrades to handle extra demand.
- Fire safety requirements to meet California codes.
- Choosing a reputable ADU company with local experience.
- Understanding solar panel rules for compliance and long-term savings.
By focusing on these factors, you can save time, avoid expensive mistakes, and create an ADU that is safe, skilled and valuable for the years to come.
