An 1100 sq ft ADU is among the largest units allowed in California, offering nearly full-size home functionality. With space for 2–3 bedrooms, multiple bathrooms, and generous living areas, an 1100-square-foot ADU is well-suited for families, multi-generational living, or as a premium rental property. This size sits just below the maximum ADU limit, giving homeowners almost complete design flexibility.
Here’s how the construction cost for an 1100 SF ADU typically breaks down:
| Category | Estimated Cost Range |
|---|---|
| Construction (hard) | $210,000 – $300,000 |
| Site prep & utilities | $20,000 – $45,000 |
| Design & engineering | $12,000 – $25,000 |
| Permits & city fees | $8,000 – $17,000 |
| Total | $250,000 – $390,000+ |
Most 1100-square-foot ADUs complete in the $270k–$330k range, depending on finishes, site prep, and local permitting requirements.
💡 Tip: With almost the same footprint as the maximum-size ADU, an 1100 SF build can support highly functional floor plans without the full costs of a 1200 sq ft project.
A typical 1100 sq ft ADU in California follows this schedule:
💡 Ataman Studio coordinates every stage — from design to permits and construction oversight — helping homeowners avoid delays and manage costs effectively.
An 1100-square-foot ADU is one of the largest and most versatile sizes available, perfect for family living or strong rental income. Nearly at the legal maximum, it offers the space of a small home while keeping construction costs below a new primary house. Request your tailored estimate today.
