How Much Does an ADU Cost in Folsom?
Updated June 12, 2026 · Upside ADU
Quick answer
A detached ADU in Folsom costs about $137,500–$475,200 turnkey in 2026, or roughly $275–$396 per square foot (design, permits, and construction included). A 750 sq ft 2-bedroom unit averages $206,250–$297,000; garage conversions and Junior ADUs cost less. Folsom runs roughly 10% above the central-Sacramento baseline, driven mostly by site conditions and finish expectations in this submarket.
What does each ADU type cost in Folsom?
Price is driven first by type, because type decides how much new structure you build. The ranges below are Folsom-specific for 2026 — the regional market adjusted for this submarket's higher build costs.
Folsom ADU cost by type — 2026 turnkey ranges
| ADU type | Typical size | $ / sq ft | Turnkey range |
|---|---|---|---|
| Detached ADU | 500–1200 sq ft | $275–$396 | $137,500–$475,200 |
| Garage Conversion ADU | 380–620 sq ft | $198–$308 | $75,240–$190,960 |
| Attached ADU | 450–850 sq ft | $264–$374 | $118,800–$317,900 |
| Junior ADU (JADU) | 220–500 sq ft | $220–$352 | $48,400–$176,000 |
| Multigenerational ADU | 600–1200 sq ft | $275–$407 | $165,000–$488,400 |
See also:Upside's published pricing · ADU builder in Folsom
What does an ADU cost per square foot in Folsom?
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 Folsom pricing.
Folsom detached ADU cost by size (2026)
| Size | Typical config | $ / sq ft | Estimated turnkey |
|---|---|---|---|
| 400 sq ft | Studio / JADU | $275–$396 | $110,000–$158,400 |
| 600 sq ft | 1 bedroom | $275–$396 | $165,000–$237,600 |
| 750 sq ft | 2 bedroom | $275–$396 | $206,250–$297,000 |
| 1000 sq ft | 2–3 bedroom | $275–$396 | $275,000–$396,000 |
What drives ADU cost up or down in Folsom?
Folsom runs roughly 10% above the central-Sacramento baseline, driven mostly by site conditions and finish expectations in this submarket.
Folsom lots: Empire Ranch and American River Canyon sit on sloped or canyon-edge parcels; Folsom Ranch lots are newer and flatter but HOA-governed.
Local permitting: Folsom's Community Development Department applies 4 ft side/rear setbacks and a 16 ft height cap, but the city's hillside and master-planned (Folsom Ranch) lots often add grading, retaining, or fire-zone requirements we scope up front. HOA review is common south of Highway 50.
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 Folsom budget — get an exact, all-in number for your lot.
Free feasibility check, no commitment. We confirm site conditions, permit fees, and your build range before you sign anything.
What will an ADU in Folsom rent for, and when does it pay back?
A typical Folsom ADU rents for $1,900–$3,000 a month in 2026. Folsom's job base and schools keep rents and resale values at the top of Sacramento County, so even higher site-work costs pencil out on appraised-value lift and premium 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 Folsom ADU cost compares across the region
Folsom sits in the Sacramento 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 Folsom-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)
- City of Folsom Community Development Department — permits & fees — City of Folsom Community Development Department