How Much Does an ADU Cost in Granite Bay?
Updated June 12, 2026 · Upside ADU
Quick answer
A detached ADU in Granite Bay costs about $147,500–$509,760 turnkey in 2026, or roughly $295–$425 per square foot (design, permits, and construction included). A 750 sq ft 2-bedroom unit averages $221,250–$318,600; garage conversions and Junior ADUs cost less. Granite Bay runs roughly 18% above the central-Sacramento baseline, driven mostly by site conditions and finish expectations in this submarket.
What does each ADU type cost in Granite Bay?
Price is driven first by type, because type decides how much new structure you build. The ranges below are Granite Bay-specific for 2026 — the regional market adjusted for this submarket's higher build costs.
Granite Bay ADU cost by type — 2026 turnkey ranges
| ADU type | Typical size | $ / sq ft | Turnkey range |
|---|---|---|---|
| Detached ADU | 500–1200 sq ft | $295–$425 | $147,500–$509,760 |
| Garage Conversion ADU | 380–620 sq ft | $212–$330 | $80,712–$204,848 |
| Attached ADU | 450–850 sq ft | $283–$401 | $127,440–$341,020 |
| Junior ADU (JADU) | 220–500 sq ft | $236–$378 | $51,920–$188,800 |
| Multigenerational ADU | 600–1200 sq ft | $295–$437 | $177,000–$523,920 |
See also:Upside's published pricing · ADU builder in Granite Bay
What does an ADU cost per square foot in Granite Bay?
Smaller units cost more per foot — fixed costs like a kitchen, bath, utility hookup, and permit spread across fewer square feet. Here is a detached build at Granite Bay pricing.
Granite Bay detached ADU cost by size (2026)
| Size | Typical config | $ / sq ft | Estimated turnkey |
|---|---|---|---|
| 400 sq ft | Studio / JADU | $295–$425 | $118,000–$169,920 |
| 600 sq ft | 1 bedroom | $295–$425 | $177,000–$254,880 |
| 750 sq ft | 2 bedroom | $295–$425 | $221,250–$318,600 |
| 1000 sq ft | 2–3 bedroom | $295–$425 | $295,000–$424,800 |
What drives ADU cost up or down in Granite Bay?
Granite Bay runs roughly 18% above the central-Sacramento baseline, driven mostly by site conditions and finish expectations in this submarket.
Granite Bay lots: Los Lagos and Granite Bay Hills estate parcels easily accommodate a large custom detached ADU matched to the main home's finish level.
Local permitting: Granite Bay is unincorporated Placer County, permitting through the Community Development Resource Agency. Estate lots are large but often on septic with HOA design review (Los Lagos), so custom detached ADUs with upscale finishes are the norm and septic capacity is checked early.
The single biggest cost lever is size: keeping a unit under 750 sq ft exempts it from local impact fees. Site conditions (slope, soil, utility runs) and finish level move the rest.
Know your Granite Bay budget — get an exact, all-in number for your lot.
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What will an ADU in Granite Bay rent for, and when does it pay back?
A typical Granite Bay ADU rents for $2,000–$3,200 a month in 2026. High property values mean Granite Bay ADUs deliver outsized appraised-value gains; the typical owner is building for family or value-add rather than maximizing rent. Run your specific numbers with the calculator below, or see the full payback math in the ROI guide.
Tools & guides:ADU cost calculator · ROI & rent estimator · ADU rental income & ROI guide
How Granite Bay ADU cost compares across the region
Granite Bay sits in the Placer County market. The regional baseline is central Sacramento; foothill and estate submarkets (El Dorado Hills, Granite Bay, Folsom) run highest, while Galt, Woodland, and Citrus Heights run lowest. For the full regional cost breakdown and methodology, see our Sacramento ADU cost guide, or compare every city on the ADU cost by city index.
Figures are 2026 Granite Bay-area market estimates, not a fixed quote. Your exact price depends on your lot, design, and finish level — we confirm it with a free feasibility check.
Sources & references
- Accessory Dwelling Units — official guidance — California Dept. of Housing & Community Development (HCD)
- Placer County Community Development Resource Agency — permits & fees — Placer County Community Development Resource Agency