SOME TAKEAWAYS
ADU projects offer multiple construction options to fit each situation.
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- Stick-built, panelized, and modular construction each offer distinct advantages and tradeoffs.
- The right fit depends on your site, budget, and design goals.
- Evaluate options early with your project team to start in the right direction.
State laws have made ADUs easier to build in California.
- Most ADUs are approved through a simple, standard review.
- Conversions and ADUs under 800 sq. ft. have extra protections under state law.
- Permits are typically issued within 60 days, though timelines can vary.
Site conditions can affect the cost and feasibility of an ADU.
- Hillsides, soil conditions, and hazard zones may require additional engineering.
- Easements, setbacks, and lot constraints can limit where you can build.
- Properties with septic systems or near creeks may need additional review.
Starting utility planning early can help your ADU project stay on schedule.
- Upgrades to electric, sewer, or water service can add cost, making it helpful to review these needs early.
- Utility connections, including PG&E meter work, can take time to schedule and often need advance notice.
STICK-BUILT CONSTRUCTION offers the most flexibility and customization.
- Built on-site using traditional methods, it allows full control over layout and design.
- Timelines may be longer due to permitting, inspections, and weather, but this approach works well for homeowners who want maximum design control.
PANELIZED CONSTRUCTION balances customization and efficiency.
- Panels are built in a factory and assembled on-site, allowing faster construction while still supporting flexible design.
- This method works well on sites with limited access, with a contractor completing the foundation, utilities, and finishing details.
MODULAR CONSTRUCTION can help shorten build timelines.
- Units are built in a factory while site work happens in parallel, and many arrive nearly complete.
- Design flexibility varies by provider but is often greater than homeowners expect.
All ADUs require some on-site work, including foundation, utilities, and site preparation. A contractor is usually involved, and the main difference between methods is where the structure is built and assembled.
Planning ahead can help avoid delays and surprises. Permitting timelines and utility coordination are common challenges, and early review of site conditions and infrastructure can make a big difference. Working with experienced local professionals can help keep your project moving smoothly.
Thank you to our guest presenters for sharing their expertise and helping homeowners better understand the ADU process.
