Two separate layers of protection
When homeowners ask "what's the warranty on my ADU," there are really two different things they might be asking about: the specific written warranty your contractor provides as part of your construction contract, and California's statutory construction-defect framework (commonly associated with the Right to Repair Act, Civil Code Sections 895–945.5), which applies more broadly to residential construction defects.
Your contractor's written warranty
This is the promise spelled out in your actual construction contract — what's covered, for how long, and what your contractor will do if something fails. This varies significantly by contractor, so it's worth reading closely and asking specific questions before signing, not assuming a standard length applies. See our guide to comparing contractor bids for how warranty terms should factor into your decision.
California's statutory framework: general periods
Separately, California law establishes specific timeframes for different categories of construction defects in residential construction. As commonly summarized: fit-and-finish items (cabinets, paint, flooring, trim) generally carry a 1-year period; plumbing and electrical systems generally carry a 4-year period; and structural and other major components are generally subject to up to a 10-year period from substantial completion.
| Component Category | General Statutory Period |
|---|---|
| Fit and finish (cabinets, paint, flooring, trim) | 1 year |
| Plumbing and electrical systems | 4 years |
| Structural components, foundations, major systems | Up to 10 years |
An important nuance for ADUs specifically
California's statutory Right to Repair framework was written with new single-family home construction as its primary context. Whether and how it applies the same way to a detached ADU, an attached addition, or a conversion project is a more nuanced legal question than a simple summary can answer — and it may differ depending on your specific project type. This is exactly the kind of question worth raising directly with your contractor and, if needed, a construction attorney, rather than assuming a specific statutory period automatically applies to your ADU.
Questions worth asking before you sign
- What does the written warranty in my contract actually cover, and for how long? Get this in writing, not just a verbal assurance.
- Are subcontracted systems (electrical, plumbing, HVAC) separately warrantied by their installers? Sometimes these carry their own manufacturer or installer warranties independent of your general contractor's warranty.
- What's the process if something fails after move-in? Understand who you'd contact and what the expected response time looks like.
- Does the warranty transfer if I sell the property? This can matter for resale, particularly within the first few years.
This is general information, not legal advice
Construction defect law is detailed and fact-specific. This page describes general categories and commonly cited timeframes, not a legal determination for your specific project or contract. A construction attorney can advise on your specific rights and remedies if you're facing an actual issue.
Frequently asked questions
Not automatically in the way people often assume — California's statutory framework establishes different periods for different types of defects (1, 4, and up to 10 years depending on the component), and how it applies to an ADU specifically versus a full new home can be a nuanced question. Your contractor's written warranty is a separate, specific promise worth reviewing directly.
Your contractor's warranty is a specific promise in your contract. Statutory construction-defect rights exist separately under California law, regardless of what your contract says, though the specifics of how they apply can vary by project type.
Yes — always confirm warranty terms in your written construction contract rather than relying on a verbal promise, and ask specific questions about coverage, duration, and the claims process before you sign.