ADU Cost (2026)
By the Home Repair One data team · Updated July 2026 · Ranges from our estimator engine
Short answer: In 2026, an accessory dwelling unit typically runs $98,000–$550,000. A studio around 400 square feet is about $98,000–$145,000 at a standard finish. A 1-bed around 700 square feet lands $170,000–$255,000 standard, or $260,000–$385,000 custom. A 2-bed around 1,000 square feet can reach $245,000–$365,000 standard, and a custom finish on that size can approach $550,000. ADUs cost more per square foot than a full house because a kitchen, a bath, and permits are packed into a small footprint. Site work, utility hookups, and local ADU rules move the number as much as the floor plan.
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ADU cost by size
Square footage sets the base. Here are 2026 national ranges at standard finish from our cost model.
| Scope | Typical range |
|---|---|
| Studio ADU (~400 sq ft) | $98,000–$145,000 |
| 1-bed ADU (~700 sq ft) | $170,000–$255,000 |
| 2-bed ADU (~1,000 sq ft) | $245,000–$365,000 |
Standard versus custom
A full kitchen and bath in a tight envelope is already expensive. Custom cabinets, windows, and a second-story unit over the garage push it higher. Here is a typical 1-bed across standard and custom tiers.
| Material / finish | Typical range |
|---|---|
| Standard build | $170,000–$255,000 |
| Custom / premium | $260,000–$385,000 |
What the per-foot ads skip
Detached new-build, garage conversion, and a unit over the garage are different jobs. Utility laterals, setbacks, parking, and a second address are real lines. A licensed GC pulls the permit. Conversion of an existing garage still needs one.
What changes your price
- Square footage: studio, 1-bed, or 2-bed.
- Standard versus custom finish, and a full kitchen plus bath in a small footprint.
- Detached new-build versus garage conversion versus a unit over the garage.
- Local ADU ordinances, setbacks, parking, and utility hookups.
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FAQ
How much does an ADU cost?
A studio starts near $98,000. A typical 1-bed standard build lands about $170,000–$255,000. A custom 2-bed can reach $550,000. Our estimator ranges it by size and finish.
Why is an ADU more per square foot than a house?
A kitchen and a bath are the expensive rooms, and an ADU still needs both. Permits, utility laterals, and a second address on a tight lot add cost that a large house spreads over more floor.
Do I need a permit to build an ADU?
Yes. ADUs are dwellings. Zoning, setbacks, parking, and utility capacity are the usual gates. A licensed GC pulls the permit. Converting a garage still needs one.